William V Boynton

Contact

(520) 621-6941
Gerard P. Kuiper Space Sci., Rm. 343
Tucson, AZ 85721
wboynton@arizona.edu

Bio

No activities entered.

Interests

No activities entered.

Courses

No activities entered.

Scholarly Contributions

Journals/Publications

Abbott, B., Abbott, R., Abbott, T., Abraham, S., Acernese, F., Ackley, K., Adams, C., Adhikari, R., Adya, V., Affeldt, C., Agathos, M., Agatsuma, K., Aggarwal, N., Aguiar, O., Aiello, L., Ain, A., Ajith, P., Allen, G., Allocca, A., , Aloy, M., et al. (2019). Search for Gravitational-wave Signals Associated with Gamma-Ray Bursts during the Second Observing Run of Advanced LIGO and Advanced Virgo. \apj, 886(1), 75.
Barnouin}, O., Daly, M., Palmer, E., Gaskell, R., Weirich, J., Johnson, C., Al, A. M., Roberts, J., Perry, M., Susorney, H., Daly, R., Bierhaus, E., Seabrook, J., Espiritu, R., Nair, A., Nguyen, L., Neumann, G., Ernst, C., Boynton, W., , Nolan, M., et al. (2019). Shape of (101955) Bennu indicative of a rubble pile with internal stiffness. Nature Geoscience, 12(4), 247-252.
Hamilton}, V., Simon, A., Christensen, P., Reuter, D., Clark, B., Barucci, M., Bowles, N., Boynton, W., Brucato, J., Cloutis, E., Connolly, H., Donaldson, H. K., Emery, J., Enos, H., Fornasier, S., Haberle, C., Hanna, R., Howell, E., Kaplan, H., , Keller, L., et al. (2019). Evidence for widespread hydrated minerals on asteroid (101955) Bennu. Nature Astronomy, 3, 332-340.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Kozlova, A., Golenetskii, S., Aptekar, R., Frederiks, D., Svinkin, D., Cline, T., Goldstein, A., Briggs, M., Wilson-Hodge, C. .., Barthelmy, S., Cummings, J., Krimm, H., Palmer, D., Boynton, W., , Fellows, C., et al. (2019). IPN Triangulation of GRB 190304A (long).. GRB Coordinates Network, 23942, 1.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Kozlova, A., Golenetskii, S., Aptekar, R., Frederiks, D., Svinkin, D., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Barthelmy, S., Cummings, J., , Krimm, H., et al. (2019). IPN triangulation of GRB 190103A (long).. GRB Coordinates Network, 23646, 1.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Barthelmy, S., Cummings, J., , Krimm, H., et al. (2019). IPN Triangulation of GRB 190117A (long).. GRB Coordinates Network, 23764, 1.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Boynton, W., Fellows, C., , Harshman, K., et al. (2019). IPN Triangulation of GRB 190129B (long/extremely bright).. GRB Coordinates Network, 23808, 1.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Boynton, W., Fellows, C., , Harshman, K., et al. (2019). Improved IPN error box for GRB 190129B.. GRB Coordinates Network, 23822, 1.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Goldstein, A., Briggs, M., , Wilson-Hodge, C. .., et al. (2019). IPN Triangulation of GRB 190611B.. GRB Coordinates Network, 24811, 1.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Ursi, A., Parmiggiani, N., , Verrecchia, F., et al. (2019). IPN Triangulation of GRB 190329A (long/bright).. GRB Coordinates Network, 24029, 1.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Ursi, A., Parmiggiani, N., , Verrecchia, F., et al. (2019). IPN Triangulation of GRB 190501A (long/bright).. GRB Coordinates Network, 24372, 1.
Hurley, K., Tsvetkova, A., Svinkin, D., Aptekar, R., Frederiks, D., Golenetskii, S., Kokomov, A., Kozlova, A., Lysenko, A., Ulanov, M., Cline, T., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Boynton, W., Harshman, K., Fellows, C., Starr, R., , Rau, A., et al. (2019). A Search for Gravitationally Lensed Gamma-Ray Bursts in the Data of the Interplanetary Network and Konus-Wind. \apj, 871(1), 121.
Lauretta}, D., Dellagiustina, D., Bennett, C., Golish, D., Becker, K., Balram-Knutson, S., Barnouin, O., Becker, T., Bottke, W., Boynton, W., Campins, H., Clark, B., Connolly, H., Drouet, D. C., Dworkin, J., Emery, J., Enos, H., Hamilton, V., Hergenrother, C., , Howell, E., et al. (2019). The unexpected surface of asteroid (101955) Bennu. \nat, 568(7750), 55-60.
Moreau, M., Nolan, M. C., Boynton, W. V., Enos, H., Bartels, A., Calloway, A., Mink, R., Leonard, J., Antreasian, P., DellaGiustina, D., Harshman, K., Balram-Knutson, S., Bennett, C., Cambioni, S., Fisher, M., Freund, S., Bierhaus, E., May, C., Fitzgibbon, M., , Patel, J., et al. (2019). OSIRIS-REx low-velocity particles during outbound cruise. Advances in Space Research, 63, 672-691.
Rizk, B., Drouet, d. C., Hergenrother, C., Bos, B., Golish, D., Malhotra, R., Lauretta, D., Butt, J., Patel, J., Fitzgibbon, M., May, C., Bierhaus, E., Freund, S., Fisher, M., Cambioni, S., Bennett, C., Balram-Knutson, S., Harshman, K., DellaGiustina, D., , Antreasian, P., et al. (2019). OSIRIS-REx low-velocity particles during outbound cruise. Advances in Space Research, 63(1), 672-691.
Seabrook, J., Daly, M., Barnouin, O., Johnson, C., Nair, A., Bierhaus, E., Boynton, W., Espiritu, R., Gaskell, R., Palmer, E., Nguyen, L., Nolan, M., & Lauretta, D. (2019). Global shape modeling using the OSIRIS-REx scanning Laser Altimeter. \planss, 177, 104688.
Tate, C., Moersch, J., Mitrofanov, I., Litvak, M., Bellutta, P., Boynton, W., Cagle, N., Ehresmann, B., Fedosov, F., Golovin, D., Hardgrove, C., Harshman, K., Hassler, D., Jun, I., Kozyrev, A., Lisov, D., Malakhov, A., Mischna, M., Nikiforov, S., , Sanin, A., et al. (2019). Mars Science Laboratory Dynamic Albedo of Neutrons passive mode data and results from sols 753 to 1292: Pahrump Hills to Naukluft Plateau. \icarus, 330, 75-90.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Kozlova, A., Golenetskii, S., Aptekar, R., Frederiks, D., Svinkin, D., Cline, T., Connaughton, V., Briggs, M., Meegan, C., Pelassa, V., Goldstein, A., Kienlin, A., Zhang, X., Rau, A., , Savchenko, V., et al. (2018). IPN Triangulation of GRB 180113C.. GRB Coordinates Network, Circular Service, No.~22349, \#1 (2018/January-0), 22349.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Kozlova, A., Golenetskii, S., Aptekar, R., Frederiks, D., Svinkin, D., Cline, T., Connaughton, V., Briggs, M., Meegan, C., Pelassa, V., Goldstein, A., Kienlin, A., Zhang, X., Rau, A., , Savchenko, V., et al. (2018). IPN Triangulation of GRB 180409A.. GRB Coordinates Network, Circular Service, No.~22619, \#1 (2018/April-0), 22619.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Kozlova, A., Golenetskii, S., Aptekar, R., Frederiks, D., Svinkin, D., Cline, T., Goldstein, A., Briggs, M., Wilson-Hodge, C. .., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., , Ferrigno, C., et al. (2018). IPN Triangulation of GRB 180703A.. GRB Coordinates Network, Circular Service, No.~22925, \#1 (2018/July-0), 22925.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Kozlova, A., Golenetskii, S., Aptekar, R., Frederiks, D., Svinkin, D., Cline, T., Goldstein, A., Briggs, M., Wilson-Hodge, C. .., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., , Ferrigno, C., et al. (2018). IPN Triangulation of GRB 180703B.. GRB Coordinates Network, Circular Service, No.~22908, \#1 (2018/July-0), 22908.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Kozlova, A., Golenetskii, S., Aptekar, R., Frederiks, D., Svinkin, D., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Barthelmy, S., Cummings, J., , Krimm, H., et al. (2018). IPN Triangulation of GRB 180223A (long).. GRB Coordinates Network, Circular Service, No.~22451, \#1 (2018/February-0), 22451.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Barthelmy, S., Cummings, J., Krimm, H., Palmer, D., Boynton, W., Fellows, C., Harshman, K., Enos, H., & Starr, R. (2018). IPN Triangulation of GRB 180318A (long).. GRB Coordinates Network, Circular Service, No.~22522, \#1 (2018/March-0), 22522.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Connaughton, V., Briggs, M., Meegan, C., Pelassa, V., Goldstein, A., Kienlin, A., Zhang, X., Rau, A., , Savchenko, V., et al. (2018). IPN Triangulation of GRB 180427A.. GRB Coordinates Network, Circular Service, No.~22679, \#1 (2018/April-0), 22679.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Goldstein, A., Briggs, M., Wilson-Hodge, C. .., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., , Ferrigno, C., et al. (2018). IPN Triangulation of GRB 181028A (long).. GRB Coordinates Network, Circular Service, No.~23388, \#1 (2018), 23388.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Goldstein, A., Briggs, M., Wilson-Hodge, C. .., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., , Ferrigno, C., et al. (2018). IPN Triangulation of GRB 181212A (long).. GRB Coordinates Network, Circular Service, No.~23534, \#1 (2018/December-0), 23534.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Boynton, W., Fellows, C., , Harshman, K., et al. (2018). IPN Triangulation of GRB 180326A (long).. GRB Coordinates Network, Circular Service, No.~22550, \#1 (2018/March-0), 22550.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Boynton, W., Fellows, C., , Harshman, K., et al. (2018). IPN Triangulation of GRB 181011A (long).. GRB Coordinates Network, Circular Service, No.~23328, \#1 (2018), 23328.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Ursi, A., Parmiggiani, N., , Verrecchia, F., et al. (2018). IPN Triangulation of GRB 180404C (long).. GRB Coordinates Network, Circular Service, No.~22610, \#1 (2018/April-0), 22610.
Lauretta, D. S., Lauretta, D. S., Enos, H., Enos, H., Clark, B., Clark, B., Campins, H., Campins, H., Licandro, J., Licandro, J., Rizos, J., Rizos, J., Le{'on}, J., Le{'on}, J., Kinney-Spano, E., Kinney-Spano, E., Crombie, M., Crombie, M., Rizk, B., , Rizk, B., et al. (2018). Overcoming the Challenges Associated with Image-Based Mapping of Small Bodies in Preparation for the OSIRIS-REx Mission to (101955) Bennu. Earth and Space Science, 5, 929-949.
Livengood, T., Mitrofanov, I., Chin, G., Boynton, W., Bodnarik, J., Evans, L., Harshman, K., Litvak, M., McClanahan, T., Sagdeev, R., Sanin, A., Starr, R., & Su, J. (2018). Background and lunar neutron populations detected by LEND and average concentration of near-surface hydrogen near the Moon's poles. \planss, 162, 89-104.
McClanahan, T., Mitrofanov, I., Boynton, W., Chin, G., Livengood, T., Sanin, A., Litvak, M., Parsons, A., Hamara, D., Harshman, K., Starr, R., & Su, J. (2018). Lunar Regolith Geochemistry Variation May Explain the Polar Wander Observations. LPI Contributions, 2087, 5012.
Sanin, A., Mitrofanov, I., Litvak, M., Bakhtin, B., Boynton, W., Chin, G., Harshman, K., Golovin, D., Kozyrev, A., Livengood, T., Malakhov, A., McClanahan, T., Mokrousov, M., Starr, R., Sagdeev, R., & Tret'yakov, V. (2018). Moon South Pole Mapping by LEND Instrument. European Planetary Science Congress, 12, EPSC2018-473.
Starr, R., Litvak, M., Petro, N., Mitrofanov, I., Boynton, W., Chin, G., Livengood, T., McClanahan, T., Sanin, A., Sagdeev, R., & Su, J. (2018). Crater age and hydrogen content in lunar regolith from LEND neutron data. \planss, 162, 105-112.
Tate, C., Moersch, J., Jun, I., Mitrofanov, I., Litvak, M., Boynton, W., Drake, D., Fedosov, F., Golovin, D., Hardgrove, C., Harshman, K., Kozyrev, A., Kuzmin, R., Lisov, D., Maclennan, E., Malakhov, A., Mischna, M., Mokrousov, M., Nikiforov, S., , Sanin, A., et al. (2018). Observed diurnal variations in Mars Science Laboratory Dynamic Albedo of Neutrons passive mode data. Nuclear Instruments and Methods in Physics Research A, 892, 70-83.
Tate, C., Moersch, J., Mitrofanov, I., Litvak, M., Bellutta, P., Boynton, W., Drake, D., Ehresmann, B., Fedosov, F., Golovin, D., Hardgrove, C., Harshman, K., Hassler, D., Jun, I., Kozyrev, A., Lisov, D., Malakhov, A., Ming, D., Mischna, M., , Mokrousov, M., et al. (2018). Results from the dynamic albedo of neutrons (DAN) passive mode experiment: Yellowknife Bay to Amargosa Valley (Sols 201-753). \icarus, 299, 513-537.
Hurley, K., Aptekar, R., Golenetskii, S., Frederiks, D., Svinkin, D., Pal'Shin, V., Briggs, M., Meegan, C., Connaughton, V., Goldsten, J., Boynton, W., Fellows, C., Harshman, K., Mitrofanov, I., Golovin, D., Kozyrev, A., Litvak, M., Sanin, A., Rau, A., , Kienlin, A., et al. (2017). VizieR Online Data Catalog: IPN supplement to the 2nd Fermi GBM catalog (Hurley+, 2017). VizieR Online Data Catalog, 222.
Hurley, K., Aptekar, R., Golenetskii, S., Frederiks, D., Svinkin, D., Pal'shin, V., Briggs, M., Meegan, C., Connaughton, V., Goldsten, J., Boynton, W., Fellows, C., Harshman, K., Mitrofanov, I., Golovin, D., Kozyrev, A., Litvak, M., Sanin, A., Rau, A., , Kienlin, A., et al. (2017). The InterPlanetary Network Supplement to the Second Fermi GBM Catalog of Cosmic Gamma-Ray Bursts. \apjs, 229, 31.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Kozlova, A., Golenetskii, S., Aptekar, R., Frederiks, D., Svinkin, D., Cline, T., Connaughton, V., Briggs, M., Meegan, C., Pelassa, V., Goldstein, A., Kienlin, A., Zhang, X., Rau, A., , Savchenko, V., et al. (2017). IPN Triangulation of GRB 170115B.. GRB Coordinates Network, Circular Service, No.~20475, \#1 (2017), 20475.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Kozlova, A., Golenetskii, S., Aptekar, R., Frederiks, D., Svinkin, D., Cline, T., Connaughton, V., Briggs, M., Meegan, C., Pelassa, V., Goldstein, A., Kienlin, A., Zhang, X., Rau, A., , Savchenko, V., et al. (2017). IPN Triangulation of GRB 170209A.. GRB Coordinates Network, Circular Service, No.~20656, \#1 (2017), 20656.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Kozlova, A., Golenetskii, S., Aptekar, R., Frederiks, D., Svinkin, D., Cline, T., Connaughton, V., Briggs, M., Meegan, C., Pelassa, V., Goldstein, A., Kienlin, A., Zhang, X., Rau, A., , Savchenko, V., et al. (2017). IPN Triangulation of GRB 170826B.. GRB Coordinates Network, Circular Service, No.~21753, \#1 (2017), 21753.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Kozlova, A., Golenetskii, S., Aptekar, R., Frederiks, D., Svinkin, D., Cline, T., Connaughton, V., Briggs, M., Meegan, C., Pelassa, V., Goldstein, A., Kienlin, A., Zhang, X., Rau, A., , Savchenko, V., et al. (2017). IPN Triangulation of GRB 170921B.. GRB Coordinates Network, Circular Service, No.~21918, \#1 (2017), 21918.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Kozlova, A., Golenetskii, S., Aptekar, R., Frederiks, D., Svinkin, D., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Connaughton, V., Briggs, M., , Meegan, C., et al. (2017). IPN Triangulation of GRB 171022A.. GRB Coordinates Network, Circular Service, No.~22051, \#1-2018 (2017), 22051.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Barthelmy, S., Cummings, J., Krimm, H., Palmer, D., Boynton, W., Fellows, C., Harshman, K., Enos, H., & Starr, R. (2017). IPN Triangulation of GRB 170311B (long/very intense).. GRB Coordinates Network, Circular Service, No.~20859, \#1 (2017), 20859.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Barthelmy, S., Cummings, J., Krimm, H., Palmer, D., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., , Bozzo, E., et al. (2017). IPN Triangulation of GRB 170805A (short).. GRB Coordinates Network, Circular Service, No.~21427, \#1 (2017), 21427.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Connaughton, V., Briggs, M., Meegan, C., Pelassa, V., Goldstein, A., Barthelmy, S., Cummings, J., Gehrels, N., , Krimm, H., et al. (2017). IPN Triangulation of GRB 170210A.. GRB Coordinates Network, Circular Service, No.~20661, \#1 (2017), 20661.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Connaughton, V., Briggs, M., Meegan, C., Pelassa, V., Goldstein, A., Kienlin, A., Zhang, X., Rau, A., , Savchenko, V., et al. (2017). IPN Triangulation of GRB 170206A (short/hard).. GRB Coordinates Network, Circular Service, No.~20623, \#1 (2017), 20623.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Connaughton, V., Briggs, M., Meegan, C., Pelassa, V., Goldstein, A., Kienlin, A., Zhang, X., Rau, A., , Savchenko, V., et al. (2017). IPN Triangulation of GRB 170222A (short/hard).. GRB Coordinates Network, Circular Service, No.~20722, \#1 (2017), 20722.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Barthelmy, S., Cummings, J., , Krimm, H., et al. (2017). IPN Triangulation of GRB 170320A (long/intense).. GRB Coordinates Network, Circular Service, No.~20927, \#1 (2017), 20927.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Barthelmy, S., Cummings, J., , Krimm, H., et al. (2017). IPN Triangulation of GRB 170904A (long/very bright).. GRB Coordinates Network, Circular Service, No.~21820, \#1 (2017), 21820.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Svinkin, D., Golenetskii, S., Aptekar, R., Frederiks, D., Kozlova, A., Cline, T., Kienlin, A., Zhang, X., Rau, A., Savchenko, V., Bozzo, E., Ferrigno, C., Barthelmy, S., Cummings, J., , Krimm, H., et al. (2017). IPN Triangulation of GRB 171011B (long/very bright).. GRB Coordinates Network, Circular Service, No.~21998, \#1-2018 (2017), 21998.
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{Kim}, K., {Amano}, Y., {Boynton}, W., {Klingelh{\"o}fer}, G., {Br{\"u}ckner}, J., {Hasebe}, N., {Hamara}, D., {Starr}, R., {Lim}, L., {Ju}, G., {Fagan}, T., {Ohta}, T., , E. (2014). An Active X-Ray Spectrometer Proposed for the SELENE-2 Rover. Japan Society of Aeronautical Space Sciences Transactions, 12.
{Litvak}, M., {Mitrofanov}, I., {Sanin}, A., {Lisov}, D., {Behar}, A., {Boynton}, W., {Deflores}, L., {Fedosov}, F., {Golovin}, D., {Hardgrove}, C., {Harshman}, K., {Jun}, I., {Kozyrev}, A., {Kuzmin}, R., {Malakhov}, A., {Milliken}, R., {Mischna}, M., {Moersch}, J., {Mokrousov}, M., , {Nikiforov}, S., et al. (2014). Local variations of bulk hydrogen and chlorine-equivalent neutron absorption content measured at the contact between the Sheepbed and Gillespie Lake units in Yellowknife Bay, Gale Crater, using the DAN instrument onboard Curiosity. Journal of Geophysical Research (Planets), 119, 1259-1275.
{Litvak}, M., {Mitrofanov}, I., {Sanin}, A., {Lisov}, D., {Hardgrove}, C., {Boynton}, W., {Jun}, I., {Kuzmin}, R., {Mart{\'{\i}}n-Torres}, J., {Mischna}, M., {Moersch}, J., {Nikiforov}, S., {Starr}, R., {Tate}, C., , M. (2014). Joint Analysis of Bulk Water/Chlorine Distribution in the Martian Subsurface along MSL Curiosity Traverse from Comparison between DAN/MSL and other instruments observations onboard Curiosity Rover. AGU Fall Meeting Abstracts.
{Livengood}, T., {Mitrofanov}, I., {Chin}, G., {Boynton}, W., {Evans}, L., {Litvak}, M., {McClanahan}, T., {Sagdeev}, R., {Sanin}, A., {Starr}, R., , J. (2014). Estimating Background and Lunar Contribution to Neutrons Detected by the Lunar Reconnaissance Orbiter (LRO) Lunar Exploration Neutron Detector (LEND) Instrument. AGU Fall Meeting Abstracts.
{McClanahan}, T., {Mitrofanov}, I., {Boynton}, W., {Chin}, G., {Evans}, L., {Starr}, R., {Livengood}, T., {Litvak}, M., {Sanin}, A., {Murray}, J., {Parsons}, A., {Su}, J., {Bodnarik}, J., {Harshman}, K., , R. (2014). A diurnal study of lunar topography to determine regolith temperature contributions to the inference of hydrogen volatiles using epithermal neutrons from the Lunar Exploration Neutron Detector (LEND).. AGU Fall Meeting Abstracts.
{Mitrofanov}, I., {Litvak}, M., {Sanin}, A., {Starr}, R., {Lisov}, D., {Kuzmin}, R., {Behar}, A., {Boynton}, W., {Hardgrove}, C., {Harshman}, K., {Jun}, I., {Milliken}, R., {Mischna}, M., {Moersch}, J., , C. (2014). Water and chlorine content in the Martian soil along the first 1900 m of the Curiosity rover traverse as estimated by the DAN instrument. Journal of Geophysical Research (Planets), 119, 1579-1596.
{Starr}, R., {Lim}, L., {Evans}, L., {Parsons}, A., {Zolensky}, M., , W. (2014). Performance Modeling of Orbital Gamma-Ray Spectroscopy of Carbonaceous Asteroids: Monte-Carlo Modeling of the HPGe Mars Odyssey GRS. AGU Fall Meeting Abstracts.
{Tate}, C., {Moersch}, J., {Jun}, I., {Ming}, D., {Mitrofanov}, I., {Litvak}, M., {Behar}, A., {Boynton}, W., {Drake}, D., {Lisov}, D., {Mischna}, M., {Hardgrove}, C., {Milliken}, R., {Sanin}, A., {Starr}, R., {Mart{\'{\i}}n-Torres}, J., {Zorzano}, M., {Fedosov}, F., {Golovin}, D., , {Harshman}, K., et al. (2014). MSL DAN Passive Data and Interpretations. AGU Fall Meeting Abstracts.
{Walker}, E., {Mazzali}, P., {Pian}, E., {Hurley}, K., {Arcavi}, I., {Cenko}, S., {Gal-Yam}, A., {Horesh}, A., {Kasliwal}, M., {Poznanski}, D., {Silverman}, J., {Sullivan}, M., {Bloom}, J., {Filippenko}, A., {Kulkarni}, S., {Nugent}, P., {Ofek}, E., {Barthelmy}, S., {Boynton}, W., , {Goldsten}, J., et al. (2014). Optical follow-up observations of PTF10qts, a luminous broad-lined Type Ic supernova found by the Palomar Transient Factory. \mnras, 442, 2768-2779.
Boynton, W. V., Leshin, L., & et, a. l. (2013). Volatile, Isotope, and Organic Analysis of Martian Fines with the Mars Curiosity Rover. Science, 341(6153).
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Boynton, W. V., Mahaffy, P., & et, a. l. (2013). Abundance and Isotopic Composition of Gases in the Martian Atmosphere from the Curiosity Rover. Science, 341(6143), 263-266.
Boynton, W. V., Meslinm, P., & et, a. l. (2013). Soil Diversity and Hydration as Observed by ChemCam at Gale Crater, Mars. Science, 341(6153).
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Other Information: id. 1238670, Special Issue
Boynton, W. V., Stolper, E., & et, a. l. (2013). The Petrochemistry of Jake_M: A Martian Mugearite. Science, 341(6153).
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Other Information: id. 1239463, Special Issue
Boynton, W. V., Williams, R., & et, a. l. (2013). Martian Fluvial Conglomerates at Gale Crater. Science, 340(6136), 1068-1072.
Frederiks, D. D., Hurley, K., Svinkin, D. S., Pal'Shin, V., Mangano, V., Oates, S., Aptekar, R. L., Golenetskii, S. V., Mazets, E. P., Oleynik, P. P., Tsvetkova, A. E., Ulanov, M. V., Kokomov, A. A., Cline, T. L., Burrows, D. N., Krimm, H. A., Pagani, C., Sbarufatti, B., Siegel, M. H., , Mitrofanov, I. G., et al. (2013). The ultraluminous GRB 110918a. Astrophysical Journal, 779(2).
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Abstract: GRB 110918A is the brightest long gamma-ray burst (GRB) detected by Konus-WIND during its almost 19 yr of continuous observations and the most luminous GRB ever observed since the beginning of the cosmological era in 1997. We report on the final Interplanetary Network localization of this event and its detailed multiwavelength study with a number of space-based instruments. The prompt emission is characterized by a typical duration, a moderate peak energy of the time-integrated spectrum, and strong hard-to-soft evolution. The high observed energy fluence yields, at z = 0.984, a huge isotropic-equivalent energy release E iso = (2.1 ± 0.1) × 1054 erg. The record-breaking energy flux observed at the peak of the short, bright, hard initial pulse results in an unprecedented isotropic-equivalent luminosity L iso = (4.7 ± 0.2) × 1054 erg s-1. A tail of the soft γ-ray emission was detected with temporal and spectral behavior typical of that predicted by the synchrotron forward-shock model. The Swift/X-Ray Telescope and the Swift/Ultraviolet Optical Telescope observed the bright afterglow from 1.2 to 48 days after the burst and revealed no evidence of a jet break. The post-break scenario for the afterglow is preferred from our analysis, with a hard underlying electron spectrum and interstellar-medium-like circumburst environment implied. We conclude that, among the multiple reasons investigated, the tight collimation of the jet must have been a key ingredient to produce this unusually bright burst. The inferred jet opening angle of 1.°7-3.°4 results in reasonable values of the collimation-corrected radiated energy and the peak luminosity, which, however, are still at the top of their distributions for such tightly collimated events. We estimate a detection horizon for a similar ultraluminous GRB of z 7.5 for Konus-WIND and z 12 for the Swift/Burst Alert Telescope, which stresses the importance of GRBs as probes of the early Universe. © 2013. The American Astronomical Society. All rights reserved..
Hurley, K., Mitrofanov, I. G., Golovin, D., Litvak, M. L., Sanin, A. B., Boynton, W., Fellows, C., Harshman, K., Starr, R., Golenetskii, S., Aptekar, R., Mazets, E., Pal'Shin, V., Frederiks, D., Svinkin, D., Smith, D. M., Hajdas, W., Kienlin, A. V., Zhang, X., , Rau, A., et al. (2013). The interplanetary network. EAS Publications Series, 61, 459-464.
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Abstract: We describe the current, 9-spacecraft Interplanetary Network (IPN). The IPN detects about 325 gamma-ray bursts per year, of which about 100 are not localized by any other missions. We give some examples of how the data, which are public, can be utilized. © EAS, EDP Sciences 2013.
Hurley, K., Pal'Shin, V., Aptekar, R. L., Golenetskii, S. V., Frederiks, D. D., Mazets, E. P., Svinkin, D. S., Briggs, M. S., Connaughton, V., Meegan, C., Goldsten, J., Boynton, W., Fellows, C., Harshman, K., Mitrofanov, I. G., Golovin, D. V., Kozyrev, A. S., Litvak, M. L., Sanin, A. B., , Rau, A., et al. (2013). The interplanetary network supplement to the fermi GBM catalog of cosmic gamma-ray bursts. Astrophysical Journal, Supplement Series, 207(2).
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Abstract: We present Interplanetary Network (IPN) data for the gamma-ray bursts in the first Fermi Gamma-Ray Burst Monitor (GBM) catalog. Of the 491 bursts in that catalog, covering 2008 July 12 to 2010 July 11, 427 were observed by at least one other instrument in the nine-spacecraft IPN. Of the 427, the localizations of 149 could be improved by arrival time analysis (or "triangulation") . For any given burst observed by the GBM and one other distant spacecraft, triangulation gives an annulus of possible arrival directions whose half-width varies between about 0.′4 and 32°, depending on the intensity, time history, and arrival direction of the burst, as well as the distance between the spacecraft. We find that the IPN localizations intersect the 1σ GBM error circles in only 52% of the cases, if no systematic uncertainty is assumed for the latter. If a 6° systematic uncertainty is assumed and added in quadrature, the two localization samples agree about 87% of the time, as would be expected. If we then multiply the resulting error radii by a factor of three, the two samples agree in slightly over 98% of the cases, providing a good estimate of the GBM 3σ error radius. The IPN 3σ error boxes have areas between about 1 arcmin2 and 110 deg2, and are, on the average, a factor of 180 smaller than the corresponding GBM localizations. We identify two bursts in the IPN/GBM sample that did not appear in the GBM catalog. In one case, the GBM triggered on a terrestrial gamma flash, and in the other, its origin was given as "uncertain." We also discuss the sensitivity and calibration of the IPN. © 2013. The American Astronomical Society. All rights reserved.
Jun, I., Mitrofanov, I., Litvak, M. L., Sanin, A. B., Kim, W., Behar, A., Boynton, W. V., Deflores, L., Fedosov, F., Golovin, D., Hardgrove, C., Harshman, K., Kozyrev, A. S., Kuzmin, R. O., Malakhov, A., Mischna, M., Moersch, J., Mokrousov, M., Nikiforov, S., , Shvetsov, V. N., et al. (2013). Neutron background environment measured by the mars science Laboratory's dynamic albedo of neutrons instrument during the first 100 sols. Journal of Geophysical Research E: Planets, 118(11), 2400-2412.
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Abstract: The Dynamic Albedo of Neutrons (DAN) instrument on board Mars Science Laboratory has been operating successfully since the landing and has been making measurements regularly along Curiosity's traverse at the surface. DAN measures thermal (E < 0.4 eV) and epithermal neutrons (0.4 eV < E < ~1 keV) while operating in two different modes: active and passive. The active mode uses a pulsed neutron generator (PNG) to study the geological characteristics of the subsurface. In the passive mode, DAN measures the background neutron environment. This paper presents results of measurements in the passive mode from landing through to sol 100 and provides an interpretation of the data based on extensive Monte Carlo simulations. The main observations are summarized as follows: (1) the thermal neutron counts vary strongly along the rover traverse while the epithermal counts do not show much variation; (2) the neutrons from the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) are a larger contributor to the DAN passive data than the Galactic Cosmic Ray (GCR)-induced neutrons; (3) for the MMRTG neutrons, both the thermal and the epithermal counts increase as a function of the subsurface water content; (4) on the other hand, for the GCR-induced neutrons, the thermal counts increase but the epithermal counts decrease as a function of the subsurface water content; and (5) relative contributions by the MMRTG and GCR to the DAN thermal neutron counts at the Rocknest site, where the rover was stationed from sol 59 to sol 100, are estimated to be ~60% and ~40%, respectively. Key Points The DAN passive mode measures the MMRTG neutrons and GCR-induced neutrons The thermal neutron counts show strong variability along the rover traverse The majority of the DAN passive counts are from the MMRTG neutrons ©2013. American Geophysical Union. All Rights Reserved.
Pal'Shin, V., Hurley, K., Svinkin, D. S., Aptekar, R. L., Golenetskii, S. V., Frederiks, D. D., Mazets, E. P., Oleynik, P. P., Ulanov, M. V., Cline, T., Mitrofanov, I. G., Golovin, D. V., Kozyrev, A. S., Litvak, M. L., Sanin, A. B., Boynton, W., Fellows, C., Harshman, K., Trombka, J., , McClanahan, T., et al. (2013). Interplanetary network localizations of konus short gamma-ray bursts. Astrophysical Journal, Supplement Series, 207(2).
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Abstract: Between the launch of the Global Geospace Science Wind spacecraft in 1994 November and the end of 2010, the Konus-Wind experiment detected 296 short-duration gamma-ray bursts (including 23 bursts which can be classified as short bursts with extended emission). During this period, the Interplanetary Network (IPN) consisted of up to 11 spacecraft, and using triangulation, the localizations of 271 bursts were obtained. We present the most comprehensive IPN localization data on these events. The short burst detection rate, ∼18 yr-1, exceeds that of many individual experiments. © 2013. The American Astronomical Society. All rights reserved.
Boynton, W. V., Droege, G. F., Mitrofanov, I. G., McClanahan, T. P., Sanin, A. B., Litvak, M. L., Schaffner, M., Chin, G., Evans, L. G., Garvin, J. B., Harshman, K., Malakhov, A., Milikh, G., Sagdeev, R., & Starr, R. (2012). High spatial resolution studies of epithermal neutron emission from the lunar poles: Constraints on hydrogen mobility. Journal of Geophysical Research E: Planets, 117(12).
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Abstract: The data from the collimated sensors of the LEND instrument are shown to be of exceptionally high quality. Counting uncertainties are about 0.3% relative and are shown to be the only significant source of random error, thus conclusions based on small differences in count rates are valid. By comparison with the topography of Shoemaker crater, the spatial resolution of the instrument is shown to be consistent with the design value of 5km for the radius of the circle over which half the counts from the lunar surface would be determined. The observed epithermal-neutron suppression factor due to the hydrogen deposit in Shoemaker crater of 0.250.04 cps is consistent with the collimated field-of-view rate of 1.7 cps estimated by Mitrofanov et al. (2010a). The statistical significance of the neutron suppressed regions (NSRs) relative to the larger surrounding polar region is demonstrated, and it is shown that they are not closely related to the permanently shadowed regions. There is a significant increase in H content in the polar regions independent of the H content of the NSRs. The non-NSR H content increases directly with latitude, and the rate of increase is virtually identical at both poles. There is little or no increase with latitude outside the polar region. Various mechanisms to explain this steep increase in the non-NSR polar H with latitude are investigated, and it is suggested that thermal volatilization is responsible for the increase because it is minimized at the low surface temperatures close to the poles. © 2012. American Geophysical Union. All Rights Reserved.
Cannon, K. M., Sutter, B., Ming, D. W., Boynton, W. V., & Quinn, R. (2012). Perchlorate induced low temperature carbonate decomposition in the Mars Phoenix Thermal and Evolved Gas Analyzer (TEGA). Geophysical Research Letters, 39(13).
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Abstract: Simulated Thermal Evolved Gas Analyzer (TEGA) analyses have shown that a CO 2 release detected between 400°C and 680°C by the Phoenix Lander's TEGA instrument may have been caused by a reaction between calcium carbonate and hydrated magnesium perchlorate. In our experiments a CO 2 release beginning at 385 ± 12°C was attributed to calcite reacting with water vapor and HCl gas from the dehydration and thermal decomposition of Mg-perchlorate. The release of CO 2 is consistent with the TEGA detection of CO 2 released between 400 and 680°C, with the amount of CO 2 increasing linearly with added perchlorate. X-ray diffraction (XRD) experiments confirmed CaCl 2 formation from the reaction between calcite and HCl. These results have important implications for the Mars Science Laboratory (MSL) Curiosity rover. Heating soils may cause inorganic release of CO 2; therefore, detection of organic fragments, not CO 2 alone, should be used as definitive evidence for organics in Martian soils. © 2012. American Geophysical Union. All Rights Reserved.
Evans, L. G., Peplowski, P. N., Rhodes, E. A., Lawrence, D. J., McCoy, T. J., Nittler, L. R., Solomon, S. C., Sprague, A. L., Stockstill-Cahill, K. R., Starr, R. D., Weider, S. Z., Boynton, W. V., Hamara, D. K., & Goldsten, J. O. (2012). Major-element abundances on the surface of mercury: Results from the messenger gamma-ray spectrometer. Journal of Geophysical Research E: Planets, 117(11).
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Abstract: Orbital gamma-ray measurements obtained by the MESSENGER spacecraft have been analyzed to determine the abundances of the major elements Al, Ca, S, Fe, and Na on the surface of Mercury. The Si abundance was determined and used to normalize those of the other reported elements. The Na analysis provides the first abundance estimate of 2.90.1wt% for this element on Mercury's surface. The other elemental results (S/Si=0.0920.015, Ca/Si=0.240.05, and Fe/Si=0.0770.013) are consistent with those previously obtained by the MESSENGER X-Ray Spectrometer, including the high sulfur and low iron abundances. Because of different sampling depths for the two techniques, this agreement indicates that Mercury's regolith is, on average, homogenous to a depth of tens of centimeters. The elemental results from gamma-ray and X-ray spectrometry are most consistent with petrologic models suggesting that Mercury's surface is dominated by Mg-rich silicates. We also compare the results with those obtained during the MESSENGER flybys and with ground-based observations of Mercury's surface and exosphere. © 2012 American Geophysical Union All Rights Reserved.
Karunatillake, S., Gasnault, O., Squyres, S. W., Keller, J. M., Janes, D. M., Boynton, W., & Newsom, H. E. (2012). Martian Case Study of Multivariate Correlation and Regression with Planetary Datasets. Earth, Moon and Planets, 108(3-4), 253-273.
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Abstract: We synthesize multivariate correlation and regression methods to characterize unique relationships among compositional and physical properties of a planetary surface locally, regionally, and globally. Martian data including elemental mass fractions, areal fractions of mineral types, and thermal inertia constitute our case study. We incorporate techniques to address the effects of spatial autocorrelation and heteroscedasticity. We also utilize method and fit diagnostics. While the Mars Odyssey and Mars Global Surveyor missions provide the exploratory context in our discussion, our approach is applicable whenever the interrelationships of spatially binned data of continuous-valued planetary attributes are sought. For example, our regional-scale case study reinforces the strength of the spatial correlation among K, Th, and the dominant mineralogic type within northern low albedo regions (surface type 2) of Mars. Recent chemical and mineralogic data from the MESSENGER mission at Mercury and Dawn at Vesta may be analyzed effectively with these hierarchical regression methods to constrain geochemical processes. Likewise, our algorithm could be applied locally with the wide variety of compositional data expected from the MSL mission at Gale Crater in general, and the ChemCam sampling grids in particular. © 2012 Springer Science+Business Media B.V.
Litvak, M. L., Mitrofanov, I. G., Sanin, A. B., Golovin, D. V., Malakhov, A. V., Boynton, W. V., Droege, G. F., Harshman, K., Starr, R. D., Milikh, G., & Sagdeev, R. (2012). LEND neutron data processing for the mapping of the Moon. Journal of Geophysical Research E: Planets, 117(11).
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Abstract: The Lunar Exploration Neutron Detector (LEND) aboard the Lunar Reconnaissance Orbiter (LRO) has been mapping the neutron flux from the Moon since July 2009. LEND has four different types of neutron detectors which allow a comprehensive study of lunar neutron emission: a pair of omnidirectional sensors for thermal and epithermal neutrons, a pair of Doppler filter sensors for thermal neutrons, four collimated sensors of epithermal neutrons, and a sensor of high-energy neutrons. This paper describes the data reduction procedures to convert the raw data into the higher-level PDS products containing neutron-counting rate maps of the Moon. © 2012. American Geophysical Union. All Rights Reserved.
Litvak, M. L., Mitrofanov, I. G., Sanin, A., Malakhov, A., Boynton, W. V., Chin, G., Droege, G., Evans, L. G., Garvin, J., Golovin, D. V., Harshman, K., McClanahan, T. P., Mokrousov, M. I., Mazarico, E., Milikh, G., Neumann, G., Sagdeev, R., Smith, D. E., Starr, R., & Zuber, M. T. (2012). Global maps of lunar neutron fluxes from the LEND instrument. Journal of Geophysical Research E: Planets, 117(6).
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Abstract: The latest neutron spectrometer measurements with the Lunar Exploration Neutron Detector (LEND) onboard the Lunar Reconnaissance Orbiter (LRO) are presented. It covers more than 1year of mapping phase starting on 15 September 2009. In our analyses we have created global maps showing regional variations in the flux of thermal (energy range0.5MeV), and compared these fluxes to variances in soil elemental composition, and with previous results obtained by the Lunar Prospector Neutron Spectrometer (LPNS). We also processed data from LEND collimated detectors and derived a value for the collimated signal of epithermal neutrons based on the comparative analysis with the LEND omnidirectional detectors. Finally, we have compared our final (after the data reduction) global epithermal neutron map with LPNS data. © 2012. American Geophysical Union. All Rights Reserved.
Margutti, R., Soderberg, A. M., Chomiuk, L., Chevalier, R., Hurley, K., Milisavljevic, D., Foley, R. J., Hughes, J. P., Slane, P., Fransson, C., Moe, M., Barthelmy, S., Boynton, W., Briggs, M., Connaughton, V., Costa, E., Cummings, J., Monte, E. D., Enos, H., , Fellows, C., et al. (2012). Inverse compton X-ray emission from supernovae with compact progenitors: Application to SN2011fe. Astrophysical Journal, 751(2).
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Abstract: We present a generalized analytic formalism for the inverse Compton X-ray emission from hydrogen-poor supernovae and apply this framework to SN2011fe using Swift X-Ray Telescope (XRT), UVOT, and Chandra observations. We characterize the optical properties of SN2011fe in the Swift bands and find them to be broadly consistent with a "normal" SN Ia, however, no X-ray source is detected by either XRT or Chandra. We constrain the progenitor system mass-loss rate (3σ c.l.) for wind velocity v w = 100 km s -1. Our result rules out symbiotic binary progenitors for SN 2011fe and argues against Roche lobe overflowing subgiants and main-sequence secondary stars if ≳ 1% of the transferred mass is lost at the Lagrangian points. Regardless of the density profile, the X-ray non-detections are suggestive of a clean environment (n CSM < 150 cm -3) for 2 × 10 15 ≲ R ≲ 5 × 10 16 cm around the progenitor site. This is either consistent with the bulk of material being confined within the binary system or with a significant delay between mass loss and supernova explosion. We furthermore combine X-ray and radio limits from Chomiuk et al. to constrain the post-shock energy density in magnetic fields. Finally, we searched for the shock breakout pulse using gamma-ray observations from the Interplanetary Network and find no compelling evidence for a supernova-associated burst. Based on the compact radius of the progenitor star we estimate that the shock breakout pulse was likely not detectable by current satellites. © 2012. The American Astronomical Society. All rights reserved..
Mitrofanov, I. G., Litvak, M. L., Varenikov, A. B., Barmakov, Y. N., Behar, A., Bobrovnitsky, Y. I., Bogolubov, E. P., Boynton, W. V., Harshman, K., Kan, E., Kozyrev, A. S., Kuzmin, R. O., Malakhov, A. V., Mokrousov, M. I., Ponomareva, S. N., Ryzhkov, V. I., Sanin, A. B., Smirnov, G. A., Shvetsov, V. N., , Timoshenko, G. N., et al. (2012). Dynamic Albedo of Neutrons (DAN) experiment onboard NASA's Mars Science Laboratory. Space Science Reviews, 170(1-4), 559-582.
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Abstract: The description of Dynamic Albedo of Neutrons (DAN) experiment is presented, as a part of the NASA's Mars Science Laboratory mission onboard the mars rover Curiosity. The instrument DAN includes Pulsing Neutron Generator (PNG) producing pulses of 14.1 MeV neutrons for irradiation of subsurface material below the rover, and Detectors and Electronics (DE) unit, which operates the instrument itself and measures the die-away time profiles of epithermal and thermal neutrons following each neutron pulse. It is shown that the DAN investigation will measure a content of hydrogen along the path of the MSL rover, and it will also provide information about a depth distribution of hydrogen at 10-20 regions selected for the detailed studies and sampling analysis. © 2012 Springer Science+Business Media B.V.
Mitrofanov, I., & Boynton, W. (2012). Comment on "statistics for orbital neutron spectroscopy of the Moon and other planetary bodies" by R. S. Miller. Journal of Geophysical Research E: Planets, 117(10).
Mitrofanov, I., Litvak, M., Sanin, A., Malakhov, A., Golovin, D., Boynton, W., Droege, G., Chin, G., Evans, L., Harshman, K., Fedosov, F., Garvin, J., Kozyrev, A., McClanahan, T., Milikh, G., Mokrousov, M., Starr, R., Sagdeev, R., Shevchenko, V., , Shvetsov, V., et al. (2012). Testing polar spots of water-rich permafrost on the moon: LEND observations onboard LRO. Journal of Geophysical Research E: Planets, 117(7).
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Abstract: [1] Results are presented for the LEND instrument onboard LRO for the detection of local spots of suppression and excess of epithermal neutron emission at the lunar poles. Twelve local Neutron Suppression Regions (NSRs) and Neutron Excess Regions (NERs) are detected. It is shown using the data from the LOLA and Diviner instruments that six NSRs have the empirical property "less local irradiation and lower temperature - fewer local neutrons." These NSRs may be identified with spots of water-ice rich permafrost on the Moon. It is shown that detected NSRs are include in both permanently shadowed and illuminated areas, and they are not coincident with Permanently Shadowed Regions (PSRs) at the bottom of polar craters, as has been commonly expected before LEND presented neutron data with high spatial resolution. © 2012. American Geophysical Union.
Sanders, N. E., Soderberg, A. M., Valenti, S., Foley, R. J., Chornock, R., Chomiuk, L., Berger, E., Smartt, S., Hurley, K., Barthelmy, S. D., Levesque, E. M., Narayan, G., Botticella, M. T., Briggs, M. S., Connaughton, V., Terada, Y., Gehrels, N., Golenetskii, S., Mazets, E., , Cline, T., et al. (2012). SN2010ay is a luminous and broad-lined type Ic supernova within a low-metallicity host galaxy. Astrophysical Journal, 756(2).
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Abstract: We report on our serendipitous pre-discovery detection and follow-up observations of the broad-lined TypeIc supernova (SNIc) 2010ay at z = 0.067 imaged by the Pan-STARRS1 3π survey just ∼4 days after explosion. The supernova (SN) had a peak luminosity, M R ≈ -20.2 mag, significantly more luminous than known GRB-SNe and one of the most luminous SNeIb/c ever discovered. The absorption velocity of SN2010ay is v Si 19 × 10 3kms -1 at ∼40 days after explosion, 2-5 times higher than other broad-lined SNe and similar to the GRB-SN2010bh at comparable epochs. Moreover, the velocity declines 2 times slower than other SNeIc-BL and GRB-SNe. Assuming that the optical emission is powered by radioactive decay, the peak magnitude implies the synthesis of an unusually large mass of 56Ni, M Ni = 0.9 M ⊙. Applying scaling relations to the light curve, we estimate a total ejecta mass, M ej ≈ 4.7 M ⊙, and total kinetic energy, E K ≈ 11 × 10 51 erg. The ratio of M Ni to M ej is ∼ 2 times as large for SN2010ay as typical GRB-SNe and may suggest an additional energy reservoir. The metallicity (log (O/H) PP04 + 12 = 8.19) of the explosion site within the host galaxy places SN2010ay in the low-metallicity regime populated by GRB-SNe, and ∼0.5(0.2)dex lower than that typically measured for the host environments of normal (broad-lined) SNe Ic. We constrain any gamma-ray emission with E γ ≲ 6 × 10 48erg (25-150keV), and our deep radio follow-up observations with the Expanded Very Large Array rule out relativistic ejecta with energy E ≳ 10 48erg. We therefore rule out the association of a relativistic outflow like those that accompanied SN1998bw and traditional long-duration gamma-ray bursts (GRBs), but we place less-stringent constraints on a weak afterglow like that seen from XRF060218. If this SN did not harbor a GRB, these observations challenge the importance of progenitor metallicity for the production of relativistic ejecta and suggest that other parameters also play a key role. © 2012 The American Astronomical Society. All rights reserved.
Sanin, A. B., Mitrofanov, I. G., Litvak, M. L., Malakhov, A., Boynton, W. V., Chin, G., Droege, G., Evans, L. G., Garvin, J., Golovin, D. V., Harshman, K., McClanahan, T. P., Mokrousov, M. I., Mazarico, E., Milikh, G., Neumann, G., Sagdeev, R., Smith, D. E., Starr, R. D., & Zuber, M. T. (2012). Testing lunar permanently shadowed regions for water ice: LEND results from LRO. Journal of Geophysical Research E: Planets, 117(6).
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Abstract: We use measurements from the Lunar Exploration Neutron Detector (LEND) collimated sensors during more than one year of the mapping phase of NASA's Lunar Reconnaissance Orbiter (LRO) mission to make estimates of the epithermal neutron flux within known large Permanently Shadowed Regions (PSRs). These are compared with the local neutron background measured outside PSRs in sunlit regions. Individual and collective analyses of PSR properties have been performed. Only three large PSRs, Shoemaker and Cabeus in the south and Rozhdestvensky U in the north, have been found to manifest significant neutron suppression. All other PSRs have much smaller suppression, only a few percent, if at all. Some even display an excess of neutron emission in comparison to the sunlit vicinity around them. Testing PSRs collectively, we have not found any average suppression for them. Only the group of 18 large PSRs, with area >200 km 2, show a marginal effect of small average suppression, ∼2%, with low statistical confidence. A ∼2% suppression corresponds to ∼125 ppm of hydrogen taking into account the global neutron suppression near the lunar poles and assuming a homogeneous H distribution in depth in the regolith. This means that all PSRs, except those in Shoemaker, Cabeus and Rozhdestvensky U craters, do not contain any significant amount of hydrogen in comparison with sunlit areas around them at the same latitude. © 2012. American Geophysical Union. All Rights Reserved.
Sprague, A. L., Boynton, W. V., Forget, F., Lian, Y., Richardson, M., Starr, R., Metzger, A. E., Hamara, D., & Economou, T. (2012). Interannual similarity and variation in seasonal circulation of Mars' atmospheric Ar as seen by the Gamma Ray Spectrometer on Mars Odyssey. Journal of Geophysical Research E: Planets, 117(4).
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Abstract: More than 3 Mars' years (MY) of atmospheric argon (Ar) measurements are used to study annual and seasonal variations in atmospheric transport and mixing. Data are obtained over the period 20 May 2002 to 4 May 2008 by the Gamma Subsystem (GS) of the Gamma Ray Spectrometer (GRS) on the Mars Odyssey spacecraft in orbit around Mars. Here we augment previous studies of Mars' Ar in which strong seasonal variations were observed and horizontal meridional mixing coefficients for the southern hemisphere were computed. Comparison of year-to-year seasonal abundance shows strong similarity but also some short-period (∼15-30 L s) and interannual variations. Evidence for short periods of strong eddy transport is exhibited during autumn and winter. The seasonal change in Ar concentration for southern latitudes is relatively gradual and well defined, but seasonal changes at high northern latitudes are chaotic and indicate that atmospheric disturbance is ubiquitous. Major topographic landforms (Elysium, Tharsis, Noachis Terra, Hellas) apparently have little control over seasonal Ar concentration at the spatial resolution of the GRS data set. Some indication of local enhanced Ar concentration is present from 30N to 60N for the Hellas and Tharsis sectors in late winter and early spring. The data show some significant (3) differences between MY 26 and MY 27 in geographical sectors that are likely produced by local weather. The GS data do not show seasonal variation of Ar at equatorial and low-latitude zones, in contrast to those from the Alpha Particle X-ray Spectrometer (APXS) measurements from the Mars Exploration Rovers. Copyright 2012 by the American Geophysical Union.
Sutter, B., Boynton, W. V., Ming, D. W., Niles, P. B., Morris, R. V., Golden, D. C., Lauer, H. V., Fellows, C., Hamara, D. K., & Mertzman, S. A. (2012). The detection of carbonate in the martian soil at the Phoenix Landing site: A laboratory investigation and comparison with the Thermal and Evolved Gas Analyzer (TEGA) data. Icarus, 218(1), 290-296.
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Abstract: Data collected by Phoenix Lander's Thermal and Evolved Gas Analyzer (Phoenix-TEGA) indicate carbonate thermal decomposition at both low and high temperatures. The high-temperature thermal decomposition is consistent with calcite, dolomite, or ankerite, (3-6. wt.%) or any combination of these phase or, presumably, solid solutions of these phases having intermediate composition. The low-temperature thermal decomposition is consistent with the presence of magnesite or siderite, their solid solutions, or any combination of magnesite and siderite, and possibly other carbon-bearing phases (e.g., organics). The carbonate concentration for the low temperature release, assuming magnesite-siderite, is ~1.0. wt.%. This revised interpretation of the Phoenix-TEGA data resulted from new laboratory measurements of carbonate decomposition at a Phoenix-like 12. mbar atmospheric pressure. Phoenix carbonate was inherited in ejecta from the Vastitas Borealis and Scandia regions, inherited from material deposited by aeolian processes, and/or formed in situ at the Phoenix Landing site (pedogenesis). Inherited carbonate implies multiple formation pathways may be represented by carbonates at the Phoenix Landing site. Soil carbonates and associated moderate alkalinity indicate that the soil pH is favorable for microbial activity at the Phoenix Landing site and presumably throughout the martian northern plains. © 2011 Elsevier Inc.
Vybornov, V. I., Livshits, M. A., Kashapova, L. K., Mitrofanov, I. G., Golovin, D. V., Kozyrev, A. S., Litvak, M. L., Sanin, A. B., Tret'yakov, V., Boynton, W., Shinohara, K., & Hamara, D. (2012). Observation of the powerful solar flare of October 27, 2002 on the far side of the sun. Astronomy Reports, 56(10), 805-812.
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Abstract: Observations of the hard X-ray and radio event of October 27, 2002 are analyzed. This flare was observed from near-Martian orbit by the HEND instrument developed at the Space Research Institute of the Russian Academy of Sciences and installed on the Mars Odyssey satellite. Although this powerful flare was observed far over the eastern solar limb, the extended source associated with the flare was detected by RHESSI at energies up to about 60 keV. The eruptive event was observed in the radio at the Nobeyama Radio Observatory. The properties of the X-ray radiation are used to calculate the spectrum of the accelerated electrons responsible for the observed radiation, assuming that the target is thick for a Martian observer and thin for a terrestrial observer. The results are compared with the results of radio observations. The conditions for electron propagation in the corona are discussed. © 2012 Pleiades Publishing, Ltd.
Abadie, J., Abbott, B. P., Abbott, R., Abernathy, M., Accadia, T., Acernese, F., Adams, C., Adhikari, R., Affeldt, C., Allen, B., Allen, G. S., Ceron, E. A., Amariutei, D., Amin, R. S., Anderson, S. B., Anderson, W. G., Antonucci, F., Arai, K., Arain, M. A., , Araya, M. C., et al. (2011). Search for gravitational wave bursts from six magnetars. Astrophysical Journal Letters, 734(2 PART 2).
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Abstract: Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely 1kpc from Earth, an order of magnitude closer than magnetars targeted in previous GW searches. A second, AXP 1E 1547.0-5408, gave a burst with an estimated isotropic energy >1044erg which is comparable to the giant flares. We find no evidence of GWs associated with a sample of 1279 electromagnetic triggers from six magnetars occurring between 2006 November and 2009 June, in GW data from the LIGO, Virgo, and GEO600 detectors. Our lowest model-dependent GW emission energy upper limits for band- and time-limited white noise bursts in the detector sensitive band, and for f-mode ringdowns (at 1090Hz), are 3.0 × 1044 d 21erg and 1.4 × 10 47 d 21erg, respectively, where and d 0501 is the distance to SGR 0501+4516. These limits on GW emission from f-modes are an order of magnitude lower than any previous, and approach the range of electromagnetic energies seen in SGR giant flares for the first time. © 2011. The American Astronomical Society. All rights reserved.
Corsi, A., Ofek, E. O., Frail, D. A., Poznanski, D., Arcavi, I., Gal-Yam, A., Kulkarni, S. R., Hurley, K., Mazzali, P. A., Howell, D. A., Kasliwal, M. M., Green, Y., Murray, D., Sullivan, M., Xu, D., Ben-Ami, S., Bloom, J. S., Cenko, S. B., Law, N. M., , Nugent, P., et al. (2011). PTF 10bzf (SN2010ah): A broad-line Ic supernova discovered by the Palomar Transient Factory. Astrophysical Journal, 741(2).
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Abstract: We present the discovery and follow-up observations of a broad-line Type Ic supernova (SN), PTF 10bzf (SN2010ah), detected by the Palomar Transient Factory (PTF) on 2010 February 23. The SNdistance is ≅218Mpc, greater than GRB980425/SN1998bw and GRB060218/SN2006aj, but smaller than the other SNe firmly associated with gamma-ray bursts (GRBs). We conducted a multi-wavelength follow-up campaign with Palomar 48 inch, Palomar 60 inch, Gemini-N, Keck, Wise, Swift, the Allen Telescope Array, Combined Array for Research in Millimeter-wave Astronomy, Westerbork Synthesis Radio Telescope, and Expanded Very Large Array. Here we compare the properties of PTF10bzf with those of SN1998bw and other broad-line SNe. The optical luminosity and spectral properties of PTF 10bzf suggest that this SNis intermediate, in kinetic energy and amount of 56Ni, between non-GRB-associated SNe like 2002ap or 1997ef, and GRB-associated SNe like 1998bw. No X-ray or radio counterpart to PTF10bzf was detected. X-ray upper limits allow us to exclude the presence of an underlying X-ray afterglow as luminous as that of other SN-associated GRBs such as GRB030329 or GRB031203. Early-time radio upper limits do not show evidence for mildly relativistic ejecta. Late-time radio upper limits rule out the presence of an underlying off-axis GRB, with energy and wind density similar to the SN-associated GRB030329 and GRB031203. Finally, by performing a search for a GRB in the time window and at the position of PTF 10bzf, we find that no GRB in the interplanetary network catalog could be associated with this SN. © 2011. The American Astronomical Society. All rights reserved.
Hurley, K., Atteia, J. -., Barraud, C., Pélangeon, A., Böer, M., Vanderspek, R., Ricker, G., Mazets, E., Golenetskii, S., Frederiks, D. D., Pal'Shin, V., Aptekar, R. L., Smith, D. M., Wigger, C., Hajdas, W., Rau, A., Kienlin, A. V., Mitrofanov, I. G., Golovin, D. V., , Kozyrev, A. S., et al. (2011). The interplanetary network supplement to the HETE-2 gamma-ray burst catalog. Astrophysical Journal, Supplement Series, 197(2).
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Abstract: Between 2000 November and 2006 May, one or more spacecraft of the interplanetary network (IPN) detected 226 cosmic gamma-ray bursts that were also detected by the French Gamma-Ray Telescope experiment on board the High Energy Transient Experiment 2 spacecraft. During this period, the IPN consisted of up to nine spacecraft, and using triangulation, the localizations of 157 bursts were obtained. We present the IPN localization data on these events. © 2011. The American Astronomical Society. All rights reserved.
Hurley, K., Briggs, M. S., Kippen, R. M., Kouveliotou, C., Fishman, G., Meegan, C., Cline, T., Trombka, J., McClanahan, T., Boynton, W., Starr, R., McNutt, R., & Bor, M. (2011). The interplanetary network supplement to the burst and transient source experiment 5B catalog of cosmic gamma-ray bursts. Astrophysical Journal, Supplement Series, 196(1).
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Abstract: We present Interplanetary Network localization information for 343 gamma-ray bursts observed by the Burst and Transient Source Experiment (BATSE) between the end of the 4th BATSE catalog and the end of the Compton Gamma-Ray Observatory (CGRO) mission, obtained by analyzing the arrival times of these bursts at the Ulysses, Near Earth Asteroid Rendezvous (NEAR), and CGRO spacecraft. For any given burst observed by CGRO and one other spacecraft, arrival time analysis (or "triangulation") results in an annulus of possible arrival directions whose half-width varies between 11 arcsec and 21°, depending on the intensity, time history, and arrival direction of the burst, as well as the distance between the spacecraft. This annulus generally intersects the BATSE error circle, resulting in an average reduction of the area of a factor of 20. When all three spacecraft observe a burst, the result is an error box whose area varies between 1 and 48,000 arcmin2, resulting in an average reduction of the BATSE error circle area of a factor of 87. © 2011. The American Astronomical Society. All rights reserved.
Hurley, K., Golenetskii, S., Aptekar, R., Mazets, E., Pal'shin, V., Frederiks, D., Mitrofanov, I. G., Golovin, D., Kozyrev, A., Litvak, M., Sanin, A. B., Boynton, W., Fellows, C., Harshman, K., Starr, R., Kienlin, A. V., Rau, A., Yamaoka, K., Ohno, M., , Fukazawa, Y., et al. (2011). The third interplanetary network. AIP Conference Proceedings, 1358, 385-388.
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Abstract: The 3rd interplanetary network (IPN), which has been in operation since 1990, presently consists of 9 spacecraft: AGILE, Fermi, RHESSI, Suzaku, and Swift, in low Earth orbit; INTEGRAL, in eccentric Earth orbit with apogee 0.5 light-seconds; Wind, up to ∼7 light-seconds from Earth; MESSENGER, en route to Mercury; and Mars Odyssey, in orbit around Mars. The IPN operates as a full-time, all-sky monitor for transients down to a threshold of about 6×10-7 erg cm-2 or 1 photon cm-2s-1. It detects ∼335 cosmic gamma-ray bursts per year. These events are generally not the same ones detected by narrower field of view instruments such as Swift, INTEGRAL IBIS, SuperAGILE, and MAXI; the localization accuracy is in the several arcminute and above range. The data are publicly available and can be utilized for a wide variety of studies. © 2011 American Institute of Physics.
Karunatillake, S., Squyres, S. W., Gasnault, O., Keller, J. M., Janes, D. M., Boynton, W. V., & Finch, M. J. (2011). Recipes for spatial statistics with global datasets: A martian case study. Journal of Scientific Computing, 46(3), 439-451.
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Abstract: The Mars Odyssey Gamma Ray Spectrometer has yielded planetary data of global extent. Such remote-sensing missions usually assign the value of a continuous-valued geospatial attribute to a uniform latitude-longitude grid of bins. Typical attributes include elemental-mass fraction, areal fraction of a mineral type, areal fraction of rocks, thermal inertia, etc. The fineness of the grid is chosen according to the spatial resolution of the orbiter and concomitant data processing. We describe methods to maximize the information extracted from both bin and regional data. Rigorous use of statistical parameters and related methods for inter- and intra- regional comparisons are also discussed. While we discuss results from the Mars Odyssey mission, the techniques we describe are applicable whenever continuous-valued attributes of a planet's surface are characterized with bins and regions. Our goal is to distill the simplest statistical methods for regional comparisons that would be intuitively accessible to planetary scientists. © 2010 Springer Science+Business Media, LLC.
Livshits, M. A., Golovin, D. V., Kashapova, L. K., Mitrofanov, I. G., Kozyrev, A. S., Litvak, M. L., Sanin, A. B., Tret'yakov, V., Boynton, W., Shinohara, K., & Hamara, D. (2011). Culmination of the flare activity of Group 10786 in July 2005: X-Ray observations from near-mars and near-earth orbits. Astronomy Reports, 55(6), 551-560.
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Abstract: A detailed study of two major solar flares that occurred in Group 10786 at the time of its disappearance behind the western limb is presented. The flares of July 14, 2005 were previously studied fairly poorly, as no RHESSI hard X-ray observations were available for themaxima of the twomost powerful of these flares. Observations carried out using the HEND equipment (on the Mars Odyssey spacecraft) developed at the Institute for Space Research in Moscow are used here to fill this gap. In the first flare, an intense, impulsive burst occurred at 07:23 UT, about 1.5 h after the onset of a weak, prolonged event. While processes in the neighborhood of the northern spot dominated in the flares of July 5-9, a powerful impulsive energy release on July 14 emerged when the flare process that originated in the North reached the southern spot. Our analysis of the flare activity of this medium-sized group reveals a gradual enhancement of the flare activity and a strong interaction between the acceleration above the magnetic-field neutral line and in the immediate vicinity of the spots. At the time of the culmination of the flare activity in the group on July 13 and 14, the pattern of nonstationary processes changes: fast coronal mass ejections form after a series of impulsive energy-release events. Spacecraft observations of the burst of July 14 after 11 UT at points separated in longitude (on RHESSI and Mars Odyssey) revealed clear anisotropy of the flare emission at energies exceeding 80 keV. © 2011 Pleiades Publishing, Ltd.
Livshits, M. A., Golovin, D. V., Kashapova, L. K., Mitrofanov, I. G., Kozyrev, A. S., Litvak, M. L., Sanin, A. B., Tret'yakov, V., Boynton, W., Shinohara, K., & Hamara, D. (2011). Erratum to: Culmination of the flare activity of group 10786 in July 2005: X-ray observations from near-Mars and near-Earth orbits (Astronomy Reports 6, 551 (2011)). Astronomy Reports, 55(10), 943-.
Mitrofanov, I. G., Boynton, W. V., Litvak, M. L., Sanin, A. B., & Starr, R. D. (2011). Response to comment on "Hydrogen mapping of the lunar south pole using the LRO Neutron Detector Experiment LEND". Science, 334(6059), 1058-d.
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PMID: 22116866;Abstract: Critical comments from Lawrence et al. are considered on the capability of the collimated neutron telescope Lunar Exploration Neutron Detector (LEND) on NASA's Lunar Reconnaissance Orbiter (LRO) for mapping lunar epithermal neutrons, as presented in our paper. We present two different analyses to show that our previous estimated count rates are valid and support the conclusions of that paper.
Nittler, L. R., Starr, R. D., Weider, S. Z., McCoy, T. J., Boynton, W. V., Ebel, D. S., Ernst, C. M., Evans, L. G., Goldsten, J. O., Hamara, D. K., Lawrence, D. J., McNutt Jr., R. L., E., C., Solomon, S. C., & Sprague, A. L. (2011). The major-element composition of Mercury's surface from MESSENGER X-ray spectrometry. Science, 333(6051), 1847-1850.
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PMID: 21960623;Abstract: X-ray fluorescence spectra obtained by the MESSENGER spacecraft orbiting Mercury indicate that the planet's surface differs in composition from those of other terrestrial planets. Relatively high Mg/Si and low Al/Si and Ca/Si ratios rule out a lunarlike feldspar-rich crust. The sulfur abundance is at least 10 times higher than that of the silicate portion of Earth or the Moon, and this observation, together with a low surface Fe abundance, supports the view that Mercury formed from highly reduced precursor materials, perhaps akin to enstatite chondrite meteorites or anhydrous cometary dust particles. Low Fe and Ti abundances do not support the proposal that opaque oxides of these elements contribute substantially to Mercury's low and variable surface reflectance.
Peplowski, P. N., Evans, L. G., A., S., McCoy, T. J., Boynton, W. V., Gillis-Davis, J. J., Ebel, D. S., Goldsten, J. O., Hamara, D. K., Lawrence, D. J., McNutt Jr., R. L., Nittler, L. R., Solomon, S. C., Rhodes, E. A., Sprague, A. L., Starr, R. D., & Stockstill-Cahill, K. R. (2011). Radioactive elements on Mercury's surface from MESSENGER: Implications for the planet's formation and evolution. Science, 333(6051), 1850-1852.
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PMID: 21960624;Abstract: The MESSENGER Gamma-Ray Spectrometer measured the average surface abundances of the radioactive elements potassium (K, 1150 ± 220 parts per million), thorium (Th, 220 ± 60 parts per billion), and uranium (U, 90 ± 20 parts per billion) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor materials, and supports formation from volatile-containing material comparable to chondritic meteorites. Abundances of K, Th, and U indicate that internal heat production has declined substantially since Mercury's formation, consistent with widespread volcanism shortly after the end of late heavy bombardment 3.8 billion years ago and limited, isolated volcanic activity since.
Rhodes, E. A., Evans, L. G., Nittler, L. R., Starr, R. D., Sprague, A. L., Lawrence, D. J., McCoy, T. J., Stockstill-Cahill, K. R., Goldsten, J. O., Peplowski, P. N., Hamara, D. K., Boynton, W. V., & Solomon, S. C. (2011). Analysis of MESSENGER Gamma-Ray Spectrometer data from the Mercury flybys. Planetary and Space Science, 59(15), 1829-1841.
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Abstract: During its three flybys of Mercury, the MESSENGER spacecraft made the first detection of gamma-ray emission from the planets surface. With a closest approach distance of ∼200 km, the flybys provided an opportunity to measure elemental abundances of Mercurys near-equatorial regions, which will not be visited at low altitude during MESSENGERs orbital mission phase. Despite being limited by low planetary photon flux, sufficient counts were accumulated during the first two flybys to estimate bounds on abundances for some elements having relatively strong gamma-ray spectral peaks, including Si, Fe, Ti, K, and Th. Only for Si is the standard deviation σ sufficiently small to conclude that this element was detected with 99% confidence. Iron and potassium are detected at the 2-σ (95% confidence) level, whereas only upper bounds on Ti and Th can be determined. Relative to a Si abundance assumed to be 18 weight percent (wt%), 2-σ upper bounds have been estimated as 9.7 wt% for Fe, 7.0 wt% for Ti, 0.087 wt% for K, and 2.2 ppm for Th. The relatively low upper bound on K rules out some previously suggested models for surface composition for the regions sampled. Upper bounds on Fe/Si and Ti/Si ratios are generally consistent with Ti and Fe abundances estimated from the analysis of measurements by the MESSENGER Neutron Spectrometer during the flybys but are also permissive of much lower concentrations. © 2011 Elsevier Ltd. All rights reserved.
Boynton, W. (2010). The poetry of space. Nature Geoscience, 3(10), 664-.
Gasnault, O., Taylor, G. J., Karunatillake, S., Dohm, J., Newsom, H., Forni, O., Pinet, P., & Boynton, W. V. (2010). Quantitative geochemical mapping of martian elemental provinces. Icarus, 207(1), 226-247.
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Abstract: We present an exploratory approach to the interpretation of the elemental maps produced by the Odyssey Gamma-Ray Spectrometer (GRS). These maps benefit from a direct detection of elemental mass fractions and are used to delineate and characterize elementally homogeneous provinces in the mid-latitudinal martian surface on the basis of chemistry alone. This approach is different from assessing the elemental composition of regions previously defined by their geologic context. Multivariate statistical approaches are discussed and a combination of principal component and clustering analyses is applied on the GRS-based hydrogen, chlorine, potassium, silicon, iron, and calcium maps. At least three principal components must be considered to properly describe the compositional variability seen in the maps. The main component is likely driven by the degree of mantling through a GRS perspective, i.e. by materials enriched in mobile elements (Cl, H) and finer than 10-20 cm, at horizontal and depth scales of hundreds of kilometers and tens of centimeters, respectively. Elemental diversity is found in both mantled and less-mantled provinces, suggesting both local and regional sources for the surficial materials. The less-mantled regions appear to have compositions which include basaltic igneous rocks. Although there is an absence of obvious natural clusters in the data, a solution between five and eight elemental provinces seems optimal and is discussed (Amazonis-Tharsis and Sabaea-Arabia, Tempe and the southern highlands, Chryse and Utopia, Elysium-Tartarus, Acidalia-Arabia). Future investigation of the defined elemental provinces will involve integrating other types of data and geological information. © 2009 Elsevier Inc. All rights reserved.
Hurley, K., Guidorzi, C., Frontera, F., Montanari, E., Rossi, F., Feroci, M., Mazets, E., Golenetskii, S., Frederiks, D. D., Pal'shin, V., Aptekar, R. L., Cline, T., Trombka, J., McClanahan, T., Starr, R., Atteia, J. -., Barraud, C., Pélangeon, A., Boër, M., , Vanderspek, R., et al. (2010). The interplanetary network supplement to the BeppoSAX gamma-ray burst catalogs. Astrophysical Journal, Supplement Series, 191(1), 179-184.
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Abstract: Between 1996 July and 2002 April, one or more spacecraft of the interplanetary network detected 786 cosmic gamma-ray bursts that were also detected by the Gamma-Ray Burst Monitor and/or Wide-Field X-Ray Camera experiments aboard the BeppoSAX spacecraft. During this period, the network consisted of up to six spacecraft, and using triangulation, the localizations of 475 bursts were obtained. We present the localization data for these events. © 2010. The American Astronomical Society.
Hurley, K., Rowlinson, A., Bellm, E., Perley, D., Mitrofanov, I. G., Golovin, D. V., Kozyrev, A. S., Litvak, M. L., Sanin, A. B., Boynton, W., Fellows, C., Harshmann, K., Ohno, M., Yamaoka, K., Nakagawa, Y. E., Smith, D. M., Cline, T., Tanvir, N. R., O'Brien, P., , Wiersema, K., et al. (2010). A new analysis of the short-duration, hard-spectrum GRB 051103, a possible extragalactic soft gamma repeater giant flare. Monthly Notices of the Royal Astronomical Society, 403(1), 342-352.
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Abstract: GRB 051103 is considered to be a candidate soft gamma repeater (SGR) extragalactic giant magnetar flare by virtue of its proximity on the sky to M81/M82, as well as its time history, localization and energy spectrum. We have derived a refined interplanetary network localization for this burst which reduces the size of the error box by over a factor of 2. We examine its time history for evidence of a periodic component, which would be one signature of an SGR giant flare, and conclude that this component is neither detected nor detectable under reasonable assumptions. We analyse the time-resolved energy spectra of this event with improved time and energy resolution, and conclude that although the spectrum is very hard its temporal evolution at late times cannot be determined, which further complicates the giant flare association. We also present new optical observations reaching limiting magnitudes of R>24.5, about 4-mag deeper than previously reported. In tandem with serendipitous observations of M81 taken immediately before and 1 month after the burst, these place strong constraints on any rapidly variable sources in the region of the refined error ellipse proximate to M81. We do not find any convincing afterglow candidates from either background galaxies or sources in M81, although within the refined error region we do locate two UV bright star-forming regions which may host SGRs. A supernova remnant (SNR) within the error ellipse could provide further support for an SGR giant flare association, but we were unable to identify any SNR within the error ellipse. These data still do not allow strong constraints on the nature of the GRB 051103 progenitor, and suggest that candidate extragalactic SGR giant flares will be difficult, although not impossible, to confirm. © 2010 The Authors. Journal compilation. © 2010 RAS.
Kminek, G., Rummel, J. D., Cockell, C. S., Atlas, R., Barlow, N., Beaty, D., Boynton, W., Carr, M., Clifford, S., Conley, C. A., Davila, A. F., Debus, A., Doran, P., Hecht, M., Heldmann, J., Helbert, J., Hipkin, V., Horneck, G., Kieft, T. L., , Klingelhoefer, G., et al. (2010). Report of the COSPAR mars special regions colloquium. Advances in Space Research, 46(6), 811-829.
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Abstract: In this paper we present the findings of a COSPAR Mars Special Regions Colloquium held in Rome in 2007. We review and discuss the definition of Mars Special Regions, the physical parameters used to define Mars Special Regions, and physical features on Mars that can be interpreted as Mars Special Regions. We conclude that any region experiencing temperatures > -25 °C for a few hours a year and a water activity > 0.5 can potentially allow the replication of terrestrial microorganisms. Physical features on Mars that can be interpreted as meeting these conditions constitute a Mars Special Region. Based on current knowledge of the martian environment and the conservative nature of planetary protection, the following features constitute Mars Special regions: Gullies and bright streaks associated with them, pasted-on terrain, deep subsurface, dark streaks only on a case-by-case basis, others to be determined. The parameter definition and the associated list of physical features should be re-evaluated on a regular basis. © 2010 COSPAR. Published by Elsevier Ltd. All rights reserved.
Kounaves, S. P., Hecht, M. H., Kapit, J., Gospodinova, K., Deflores, L., Quinn, R. C., Boynton, W. V., Clark, B. C., Catling, D. C., Hredzak, P., Ming, D. W., Moore, Q., Shusterman, J., Stroble, S., West, S. J., & Young, S. M. (2010). Wet Chemistry experiments on the 2007 Phoenix Mars Scout Lander mission: Data analysis and results. Journal of Geophysical Research E: Planets, 115(1).
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Abstract: Chemical analyses of three Martian soil samples were performed using the Wet Chemistry Laboratories on the 2007 Phoenix Mars Scout Lander. One soil sample was obtained from the top ∼2 cm (Rosy Red) and two were obtained at ∼5 cm depth from the ice table interface (Sorceress 1 and Sorceress 2). When mixed with water in a ∼1:25 soil to solution ratio (by volume), a portion of the soil components solvated. Ion concentrations were measured using an array of ion selective electrodes and solution conductivity using a conductivity cell. The measured concentrations represent the minimum leachable ions in the soil and do not take into account species remaining in the soil. Described is the data processing and analysis for determining concentrations of seven ionic species directly measured in the soil/solution mixture. There were no significant differences in concentrations, pH, or conductivity, between the three samples. Using laboratory experiments, refinement of the surface calibrations, and modeling, we have determined a pH for the soil solution of 7.7(±0.3), under prevalent conditions, carbonate buffering, and PCo 2 in the cell headspace. Perchlorate was the dominant anion in solution with a concentration for Rosy Red of 2.7(±1) mM. Equilibrium modeling indicates that measured [Ca2+] at 0.56(±0.5) mM and [Mg2+at 2.9(±1.5) mM, are consistent with carbonate equilibrium for a saturated solution. The [Na+] and [K+] were 1.4(±0.6), and 0.36(±0.3) mM, respectively. Results indicate that the leached portion of soils at the Phoenix landing site are slightly alkaline and dominated by carbonate and Perchlorate. However, it should be noted that there is a 5-15 mM discrepancy between measured ions and conductivity and another species may be present. Copyright 2010 by the American Geophysical Union.
Lawrence, D. J., Feldman, W. C., Goldsten, J. O., McCoy, T. J., Blewett, D. T., Boynton, W. V., Evans, L. G., Nittler, L. R., Rhodes, E. A., & Solomon, S. C. (2010). Identification and measurement of neutron-absorbing elements on Mercury's surface. Icarus, 209(1), 195-209.
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Abstract: MESSENGER Neutron Spectrometer (NS) observations of cosmic-ray-generated thermal neutrons provide the first direct measurements of Mercury's surface elemental composition. Specifically, we show that Mercury's surface is enriched in neutron-absorbing elements and has a measured macroscopic neutron-absorption cross section of 45-81×10-4cm2/g, a range similar to the neutron absorption of lunar basalts from Mare Crisium. The expected neutron-absorbing elements are Fe and Ti, with possible trace amounts of Gd and Sm. Fe and Ti, in particular, are important for understanding Mercury's formation and how its surface may have changed over time through magmatic processes. With neutron Doppler filtering - a neutron energy separation technique based on spacecraft velocity - we demonstrate that Mercury's surface composition cannot be matched by prior models, which have characteristically low abundances of Fe, Ti, Gd, and Sm. While neutron spectroscopy alone cannot separate the relative contributions of individual neutron-absorbing elements, these results provide strong new constraints on the nature of Mercury's surface materials. For example, if all the measured neutron absorption were due to the presence of an Fe-Ti oxide and that oxide were ilmenite, then Mercury's surface would have an ilmenite content of 7-18wt.%. This result is in general agreement with the inference from color imaging and visible-near-infrared spectroscopy that Mercury's overall low reflectance is consistent with a surface composition that is enriched in Fe-Ti oxides. The incorporation of substantial Fe and Ti in oxides would imply that the oxygen fugacity of basalts on Mercury is at the upper range of oxygen fugacities inferred for basalts on the Moon. © 2010 Elsevier Inc.
Mitrofanov, I. G., Bartels, A., Bobrovnitsky, Y. I., Boynton, W., Chin, G., Enos, H., Evans, L., Floyd, S., Garvin, J., Golovin, D. V., Grebennikov, A. S., Harshman, K., Kazakov, L. L., Keller, J., Konovalov, A. A., Kozyrev, A. S., Krylov, A. R., Litvak, M. L., Malakhov, A. V., , McClanahan, T., et al. (2010). Lunar exploration neutron detector for the NASA lunar reconnaissance orbiter. Space Science Reviews, 150(1-4), 183-207.
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Abstract: The design of the Lunar Exploration Neutron Detector (LEND) experiment is presented, which was optimized to address several of the primary measurement requirements of NASA's Lunar Reconnaissance Orbiter (LRO): high spatial resolution hydrogen mapping of the Moon's upper-most surface, identification of putative deposits of appreciable near-surface water ice in the Moon's polar cold traps, and characterization of the human-relevant space radiation environment in lunar orbit. A comprehensive program of LEND instrument physical calibrations is discussed and the baseline scenario of LEND observations from the primary LRO lunar orbit is presented. LEND data products will be useful for determining the next stages of the emerging global lunar exploration program, and they will facilitate the study of the physics of hydrogen implantation and diffusion in the regolith, test the presence of water ice deposits in lunar cold polar traps, and investigate the role of neutrons within the radiation environment of the shallow lunar surface. © 2009 Springer Science+Business Media B.V.
Mitrofanov, I. G., Sanin, A. B., Boynton, W. V., Chin, G., Garvin, J. B., Golovin, D., Evans, L. G., Harshman, K., Kozyrev, A. S., Litvak, M. L., Malakhov, A., Mazarico, E., McClanahan, T., Milikh, G., Mokrousov, M., Nandikotkur, G., Neumann, G. A., Nuzhdin, I., Sagdeev, R., , Shevchenko, V., et al. (2010). Hydrogen mapping of the lunar south pole using the LRO neutron detector experiment LEND. Science, 330(6003), 483-486.
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PMID: 20966247;Abstract: Hydrogen has been inferred to occur in enhanced concentrations within permanently shadowed regions and, hence, the coldest areas of the lunar poles. The Lunar Crater Observation and Sensing Satellite (LCROSS) mission was designed to detect hydrogen-bearing volatiles directly. Neutron flux measurements of the Moon's south polar region from the Lunar Exploration Neutron Detector (LEND) on the Lunar Reconnaissance Orbiter (LRO) spacecraft were used to select the optimal impact site for LCROSS. LEND data show several regions where the epithermal neutron flux from the surface is suppressed, which is indicative of enhanced hydrogen content. These regions are not spatially coincident with permanently shadowed regions of the Moon. The LCROSS impact site inside the Cabeus crater demonstrates the highest hydrogen concentration in the lunar south polar region, corresponding to an estimated content of 0.5 to 4.0% water ice by weight, depending on the thickness of any overlying dry regolith layer. The distribution of hydrogen across the region is consistent with buried water ice from cometary impacts, hydrogen implantation from the solar wind, and/or other as yet unknown sources.
Niles, P. B., Boynton, W. V., Hoffman, J. H., Ming, D. W., & Hamara, D. (2010). Stable isotope measurements of martian atmospheric CO₂ at the Phoenix landing site. Science, 329(5997), 1334-1337.
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PMID: 20829484;Abstract: Carbon dioxide is a primary component of the martian atmosphere and reacts readily with water and silicate rocks. Thus, the stable isotopic composition of CO2 can reveal much about the history of volatiles on the planet. The Mars Phoenix spacecraft measurements of carbon isotopes [referenced to the Vienna Pee Dee belemnite (VPDB)] [δ13CVPDB = -2.5 ± 4.3 per mil (‰)] and oxygen isotopes [referenced to the Vienna standard mean ocean water (VSMOW)] (δ18OVSMOW = 31.0 ± 5.7‰), reported here, indicate that CO2 is heavily influenced by modern volcanic degassing and equilibration with liquid water. When combined with data from the martian meteorites, a general model can be constructed that constrains the history of water, volcanism, atmospheric evolution, and weathering on Mars. This suggests that low-temperature water-rock interaction has been dominant throughout martian history, carbonate formation is active and ongoing, and recent volcanic degassing has played a substantial role in the composition of the modern atmosphere.
Taylor, G. J., Boynton, W. V., McLennan, S. M., & M., L. (2010). K and Cl concentrations on the Martian surface determined by the Mars Odyssey Gamma Ray Spectrometer: Implications for bulk halogen abundances in Mars. Geophysical Research Letters, 37(12).
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Abstract: Orbital gamma ray spectrometry shows that the Martian surface has a mean Cl/K ratio of 1.3 ± 0.2, indistinguishable from the ratio in CI chondrites (1.28). Although Cl and K fractionate by magma degassing and aqueous processing, during igneous partial melting both elements are highly incompatible. Thus, if the surface Cl/K reflects the bulk crustal value, then the mantle, hence primitive silicate Mars, also has a roughly CI ratio. Martian meteorite data indicate that Cl/Br is also approximately chondritic, suggesting that elements that condensed in the nebula between ∼1000 K (K and Cl) to ∼500 K (Br) are uniformly depleted in Mars at about 0.6 × CI chondrite concentrations. Mars clearly does not contain 0.6 × CI levels of H2O, which would be ∼6 wt%, indicating that Mars was constructed by planetesimals rich in volatile elements, but not in water. Copyright 2010 by the American Geophysical Union.
Taylor, G. J., Martel, L. M., Karunatillake, S., Gasnault, O., & Boynton, W. V. (2010). Mapping Mars geochemically. Geology, 38(2), 183-186.
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Abstract: Using multivariate cluster analysis, we identify six distinct geochemical provinces on Mars from the concentrations of K, Th, Fe, Si, Ca, Cl, and H2O determined by the Mars Odyssey gamma ray spectrometer. The results show that the Martian surface is dominated by basaltic rocks that vary in their abundance of incompatible (K, Th) and major elements (Fe, Si, and Ca). These chemically distinct geochemical provinces are in large, contiguous regions comprising a mixture of geologic units. The K/Th ratios are uniform among the geochemical provinces. To prevent measurable fractionation of K from Th, aqueous events must have been brief and/or the total throughput of water small. The muted weathering effects led to deposition of younger sedimentary deposits with the same compositions as older igneous units, explaining why a geochemical province may contain mapped units with the same composition but a range of ages. © 2010 Geological Society of America.
Zeitlin, C., Boynton, W., Mitrofanov, I., Hassler, D., Atwell, W., Cleghorn, T. F., Cucinotta, F. A., Dayeh, M., Desai, M., Guetersloh, S. B., Kozarev, K., Lee, K. T., Pinsky, L., Saganti, P., Schwadron, N. A., & Turner, R. (2010). Mars odyssey measurements of galactic cosmic rays and solar particles in Mars orbit, 2002-2008. Space Weather, 8(11).
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Abstract: The instrument payload aboard the 2001 Mars Odyssey orbiter includes several instruments that are sensitive to energetic charged particles from the galactic cosmic rays (GCR) and solar particle events (SPE). The Martian Radiation Environment Experiment (MARIE) was a dedicated energetic charged particle spectrometer, but it ceased functioning during the large solar storm of October/November 2003. Data from two other Odyssey instruments are used here: the Gamma Ray Spectrometer and the scintillator component of the High Energy Neutron Detector. Though not primarily designed to measure energetic charged particles, both systems are sensitive to them, and several years of data are available from both. Using the MARIE data for calibration of the other systems, count rates can be normalized (with significant uncertainties) to absolute fluxes of both GCR and solar energetic particles (SEP). The data, which cover the time span from early 2002 through the end of 2007, clearly show the solar cycle-dependent modulation of the GCR starting in 2004. Many SPEs were recorded as well and are cataloged here. Threshold energies were relatively high, ranging from 16 MeV in the most sensitive channel to 42 MeV. These thresholds are not optimal for detailed studies of SEPs, but this is the range of interest for calculations of dose and dose equivalent, pertinent to human flight, and covering that range was the original motivation for MARIE. The data are available on request and are potentially of use for the Earth-Moon-Mars Radiation Environment Module collaboration and other heliospheric modeling projects. Copyright 2010 by the American Geophysical Union.
Boynton, W. V. (2009). Honeybee and the Phoenix analysing instrument. Nature, 457(7225), 26-.
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PMID: 19122618;
Hurley, K., Cline, T., Mitrofanov, I. G., Golovin, D., Litvak, M. L., Sanin, A. B., Boynton, W., Fellows, C., Harshman, K., Starr, R., Golenetskii, S., Aptekar, R., Mazets, E., Pal'shin, V., Frederiks, D., Smith, D. M., Wigger, C., Hajdas, W., Zehnder, A., , Kienlin, A. V., et al. (2009). The status and future of the third interplanetary network. AIP Conference Proceedings, 1133, 55-57.
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Abstract: The 3rd interplanetary network (IPN), which has been in operation since 1990, presently consists of 9 spacecraft: AGILE, RHESSI, Suzaku, and Swift, in low Earth orbit; INTEGRAL, in eccentric Earth orbit with apogee 0.5 light-seconds; Wind, up to ∼7 light-seconds from Earth; MESSENGER, en route to Mercury; and Mars Odyssey, in orbit around Mars. Ulysses and HETE have ceased operations, and the Fermi GBM is being incorporated into the network. The IPN operates as a full-time, all-sky monitor for transients down to a threshold of about 6x10-7 erg cm-2 or 1 photon cm-2 s -1. It detects about 275 cosmic gamma-ray bursts per year. These events are generally not the same ones detected by narrower field of view imaging instruments such as Swift, INTEGRAL IBIS, and SuperAGILE; the localization accuracy is in the several arcminute and above range. © 2009 American Institute of Physics.
Karunatillake, S., Wray, J. J., Squyres, S. W., Taylor, G. J., Gasnault, O., McLennan, S. M., Boynton, W., R., M., & Dohm, J. M. (2009). Chemically striking regions on Mars and Stealth revisited. Journal of Geophysical Research E: Planets, 114(12).
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Abstract: The Mars Odyssey Gamma Ray Spectrometer Suite has yielded global chemical information for Mars. In this work, we establish regions of unusual chemical composition relative to average Mars primarily on the basis of Ca, Cl, Fe, H, K, Si, and Th. Using data from Mars Odyssey; the Mars Exploration Rovers; the Mars Reconnaissance Orbiter Imaging; and 3.5 cm and 1.35 cm radar observations from Earth, we examine a chemically striking ≈2.E6 km2 region and find it to overlap significantly with a radar Stealth region on Mars. It is remarkably enriched in Cl and depleted in Fe and Si (along with minor variations in H, K, and Th) relative to average Mars. Surface dust observed at the two rover sites mixed with and indurated by Ca/Mg-bearing sulfate salts would be a reasonable chemical and physical analog to meter-scale depths. We describe potential scenarios that may have contributed to the unique properties of this region. The bulk dust component may be an air fall deposit of compositionally uniform dust as observed in situ. Hydrothermal acid fog reactions on the flanks of nearby volcanoes may have generated sulfates with subsequent deflation and transport. Alternatively, sulfates may have been produced by low-temperature, regional-scale activity of ground ice-driven brine and/or regional-scale deposition of acidified H2O snowfall. Copyright 2009 by the American Geophysical Union.
Maarry, M. E., Gasnault, O., Toplis, M. J., Baratoux, D., Dohm, J. M., Newsom, H. E., Boynton, W. V., & Karunatillake, S. (2009). Gamma-ray constraints on the chemical composition of the martian surface in the Tharsis region: A signature of partial melting of the mantle?. Journal of Volcanology and Geothermal Research, 185(1-2), 116-122.
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Abstract: The Gamma-Ray Spectrometer (GRS) on board Mars Odyssey is the first instrument to provide quantitative estimates of the composition of the martian surface at the global scale. At the present time published concentration maps are available across a broad equatorial swath for Ca, Cl, Fe, H, K, Si and Th. However, it remains to be determined to what extent the observed chemical signatures are the result of primary magmatic processes or secondary alteration at the surface. With this question in mind, we have considered in detail the GRS signature on the western part of the Tharsis region including Olympus Mons. This region was chosen as it is clearly of volcanic origin, has had a prolonged magmatic history, and is of spatial extent sufficiently large that potential contributions of surrounding regions to the GRS signature are limited. It also has a characteristic composition, being notably low in silica relative to the average composition of the martian mid-latitudes. The major element chemistry of the surface in this region (SiO2, FeO, CaO, K2O) is compared with predictions of thermodynamic calculations of liquids produced by partial melting of the martian mantle composition proposed by Dreibus and Wänke [Dreibus, G., Wänke, H., 1985. Mars, a volatile-rich planet. Meteoritics 20 (No. 2), 267-381] over a range of pressures and temperatures. For all four oxides, the Tharsis compositions are consistent with liquids produced at pressures from 15 to 20 kbar, and degrees of partial melting between 3 and 10%. This pressure of melting implies a magma source depth in the range ∼ 125-170 km, consistent with current estimates of the thickness of the lithosphere in this region. The idea that the surface chemistry in the Tharsis region is dominated by the signature of primary magmatism would therefore appear to be a reasonable working hypothesis, although as more data become available, more stringent and detailed tests of this simple model will be possible. © 2008 Elsevier B.V. All rights reserved.
Mellon, M. T., Boynton, W. V., Feldman, W. C., Arvidson, R. E., N., T., Bandfield, L., Putzig, N. E., & Sizemore, H. G. (2009). A prelanding assessment of the ice table depth and ground ice characteristics in Martian permafrost at the Phoenix landing site. Journal of Geophysical Research E: Planets, 114(3).
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Abstract: We review multiple estimates of the ice table depth at potential Phoenix landing sites and consider the possible state and distribution of subsurface ice. A two-layer model of ice-rich material overlain by ice-free material is consistent with both the observational and theoretical lines of evidence. Results indicate ground ice to be shallow and ubiquitous, 2-6 cm below the surface. Undulations in the ice table depth are expected because of the thermodynamic effects of rocks, slopes, and soil variations on the scale of the Phoenix Lander and within the digging area, which can be advantageous for analysis of both dry surficial soils and buried ice-rich materials. The ground ice at the ice table to be sampled by the Phoenix Lander is expected to be geologically young because of recent climate oscillations. However, estimates of the ratio of soil to ice in the ice-rich subsurface layer suggest that that the ice content exceeds the available pore space, which is difficult to reconcile with existing ground ice stability and dynamics models. These high concentrations of ice may be the result of either the burial of surface snow during times of higher obliquity, initially high-porosity soils, or the migration of water along thin films. Measurement of the D/H ratio within the ice at the ice table and of the soil-to-ice ratio, as well as imaging ice-soil textures, will help determine if the ice is indeed young and if the models of the effects of climate change on the ground ice are reasonable. Copyright 2008 by the American Geophysical Union.
Demidov, N. E., Boynton, W. V., Gilichinsky, D. A., Zuber, M. T., Kozyrev, A. S., Litvak, M. L., Mitrofanov, I. G., Sanin, A. B., Saunders, R. S., Smith, D. E., Tretyakov, V. I., & Hamara, D. (2008). Water distribution in Martian permafrost regions from joint analysis of HEND (Mars Odyssey) and MOLA (Mars Global Surveyor) data. Astronomy Letters, 34(10), 713-723.
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Abstract: We jointly analyze data from the High-Energy Neutron Detector (HEND) onboard the NASA Mars Odyssey spacecraft and data from the Mars Orbiter Laser Altimeter (MOLA) onboard the Mars Global Surveyor spacecraft. The former instrument measures the content of hydrogen (in the form of H2O or OH) in the subsurface layer of soil and the latter instrument measures the surface albedo with respect to the flux of solar energy. We have checked the presence of a correlation between these two data sets in various Martian latitude bands. A significant correlation has been found between these data at latitudes poleward of 40° in the northern hemisphere and at latitudes 40°-60° in the southern hemisphere. This correlation is interpreted as evidence for the presence of stable water ice in these regions under a dry layer of soil whose thickness is determined by the condition for equilibrium between the condensation of water from the atmosphere and its sublimation when heated by solar radiation. For these regions, we have derived an empirical relation between the flux of absorbed solar radiation and the thickness of the top dry layer. It allows the burial depth of the water ice table to be predicted with a sub-kilometer resolution based on near-infrared albedo measurements. We have found no correlation in the southern hemisphere at latitudes >60°, although neutron data also suggest that water ice is present in this region under a layer of dry soil. We conclude that the thickness of the dry layer in this region does not correspond to the equilibrium condition between the water ice table and the atmosphere. © 2008 Pleiades Publishing, Ltd.
Giuliani, A., Mereghetti, S., Fornari, F., Monte, E. D., Feroci, M., Marisaldi, M., Esposito, P., Perotti, F., Tavani, M., Argan, A., Barbiellini, G., Boffelli, F., Bulgarelli, A., Caraveo, P., Cattaneo, P. W., Chen, W., Costa, E., D'Ammando, F., Cocco, G. D., , Donnarumma, I., et al. (2008). AGILE detection of delayed gamma-ray emission from GRB 080514B. Astronomy and Astrophysics, 491(2), L25-L28.
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Abstract: GRB 080514B is the first gamma ray burst (GRB), since the time of EGRET, for which individual photons of energy above several tens of MeV have been detected with a pair-conversion tracker telescope. This burst was discovered with the Italian AGILE gamma-ray satellite. The GRB was localized by a cooperation between AGILE and the interplanetary network (IPN). The gamma-ray imager (GRID) estimate of the position, obtained before the SuperAGILE-IPN localization, is found to be consistent with the burst position. The hard X-ray emission observed by SuperAGILE lasted about 7 s, while there is evidence that the emission above 30 MeV extends for a longer duration (at least 13 s). Similar behavior has been seen from a few other GRBs observed with EGRET. However, during the brightest phases, the latter measurements were affected by instrumental dead time effects, resulting in only lower limits to the burst intensity. Thanks to the small dead time of the AGILE/GRID we could assess that in the case of GRB 080514B the gamma-ray to X-ray flux ratio changes significantly between the prompt and extended emission phase. © 2008 ESO.
Haberle, R. M., Forget, F., Colaprete, A., Schaeffer, J., Boynton, W. V., Kelly, N. J., & Chamberlain, M. A. (2008). The effect of ground ice on the Martian seasonal CO₂ cycle. Planetary and Space Science, 56(2), 251-255.
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Abstract: The mostly carbon dioxide (CO2) atmosphere of Mars condenses and sublimes in the polar regions, giving rise to the familiar waxing and waning of its polar caps. The signature of this seasonal CO2 cycle has been detected in surface pressure measurements from the Viking and Pathfinder landers. The amount of CO2 that condenses during fall and winter is controlled by the net polar energy loss, which is dominated by emitted infrared radiation from the cap itself. However, models of the CO2 cycle match the surface pressure data only if the emitted radiation is artificially suppressed suggesting that they are missing a heat source. Here we show that the missing heat source is the conducted energy coming from soil that contains water ice very close to the surface. The presence of ice significantly increases the thermal conductivity of the ground such that more of the solar energy absorbed at the surface during summer is conducted downward into the ground where it is stored and released back to the surface during fall and winter thereby retarding the CO2 condensation rate. The reduction in the condensation rate is very sensitive to the depth of the soil/ice interface, which our models suggest is about 8 cm in the Northern Hemisphere and 11 cm in the Southern Hemisphere. This is consistent with the detection of significant amounts of polar ground ice by the Mars Odyssey Gamma Ray Spectrometer and provides an independent means for assessing how close to the surface the ice must be. Our results also provide an accurate determination of the global annual mean size of the atmosphere and cap CO2 reservoirs, which are, respectively, 6.1 and 0.9 hPa. They also indicate that general circulation models will need to account for the effect of ground ice in their simulations of the seasonal CO2 cycle. © 2007 Elsevier Ltd. All rights reserved.
Litvak, M. L., Mitrofanov, I. G., Barmakov, Y., Behar, A., Bitulev, A., Bobrovnitsky, Y., Bogolubov, E. P., Boynton, W. V., Bragin, S. I., Churin, S., Grebennikov, A. S., Konovalov, A., Kozyrev, A. S., Kurdumov, I. G., Krylov, A., Kuznetsov, Y., Malakhov, A. V., Mokrousov, M. I., Ryzhkov, V. I., , Sanin, A. B., et al. (2008). The Dynamic Albedo of Neutrons (DAN) experiment for NASA's 2009 Mars Science Laboratory. Astrobiology, 8(3), 605-612.
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PMID: 18598140;Abstract: We present a summary of the physical principles and design of the Dynamic Albedo of Neutrons (DAN) instrument onboard NASA's 2009 Mars Science Laboratory (MSL) mission. The DAN instrument will use the method of neutron-neutron activation analysis in a space application to study the abundance and depth distribution of water in the martian subsurface along the path of the MSL rover. © 2008 Mary Ann Liebert, Inc.
Mitrofanov, I. G., Sanin, A. B., Golovin, D. V., Litvak, M. L., Konovalov, A. A., Kozyrev, A. S., Malakhov, A. V., Mokrousov, M. I., Tretyakov, V. I., Troshin, V. S., Uvarov, V. N., Varenikov, A. B., Vostrukhin, A. A., Shevchenko, V. V., Shvetsov, V. N., Krylov, A. R., Timoshenko, G. N., Bobrovnitsky, Y. I., Tomilina, T. M., , Grebennikov, A. S., et al. (2008). Experiment LEND of the NASA lunar reconnaissance orbiter for high-resolution mapping of neutron emission of the moon. Astrobiology, 8(4), 793-804.
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PMID: 18844457;Abstract: The scientific objectives of neutron mapping of the Moon are presented as 3 investigation tasks of NASA's Lunar Reconnaissance Orbiter mission. Two tasks focus on mapping hydrogen content over the entire Moon and on testing the presence of water-ice deposits at the bottom of permanently shadowed craters at the lunar poles. The third task corresponds to the determination of neutron contribution to the total radiation dose at an altitude of 50 km above the Moon. We show that the Lunar Exploration Neutron Detector (LEND) will be capable of carrying out all 3 investigations. The design concept of LEND is presented together with results of numerical simulations of the instrument's sensitivity for hydrogen detection. The sensitivity of LEND is shown to be characterized by a hydrogen detection limit of about 100 ppm for a polar reference area with a radius of 5 km. If the presence of ice deposits in polar "cold traps" is confirmed, a unique record of many millions of years of lunar history would be obtained, by which the history of lunar impacts could be discerned from the layers of water ice and dust. Future applications of a LEND-type instrument for Mars orbital observations are also discussed. © 2008 Mary Ann Liebert, Inc.
Pal'shin, V., Aptekar, R., Frederiks, D., Golenetskii, S., Il'Inskii, V., Mazets, E., Yamaoka, K., Ohno, M., Hurley, K., Sakamoto, T., Oleynik, P., Ulanov, M., Mitrofanov, I. G., Golovin, D., Lirvak, M. L., Sanin, A. B., Boynton, W., Fellows, C., Harshman, K., , Shinohara, C., et al. (2008). Extremely long hard bursts observed by Konus-Wind. AIP Conference Proceedings, 1000, 117-120.
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Abstract: We report the observations of the prompt emission of the extremely long hard burst, GRB 060814B, discovered by Konus-Wind and localized by the IPN. The observations reveal a smooth, hard, ∼40-min long pulse followed by weaker emission seen several hours after the burst onset. We also present the Konus-Wind data on similar burst, GRB 971208, localized by BATSE/IPN. And finally we discuss the different possible origins of these unusual events. © 2008 American Institute of Physics.
Boynton, W. V., Sprague, A. L., Solomon, S. C., Starr, R. D., Evans, L. G., Feldman, W. C., Trombka, J. I., & Rhodes, E. A. (2007). MESSENGER and the chemistry of Mercury's surface. Space Science Reviews, 131(1-4), 85-104.
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Abstract: The instrument suite on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft is well suited to address several of Mercury's outstanding geochemical problems. A combination of data from the Gamma-Ray and Neutron Spectrometer (GRNS) and X-Ray Spectrometer (XRS) instruments will yield the surface abundances of both volatile (K) and refractory (Al, Ca, and Th) elements, which will test the three competing hypotheses for the origin of Mercury's high bulk metal fraction: aerodynamic drag in the early solar nebula, preferential vaporization of silicates, or giant impact. These same elements, with the addition of Mg, Si, and Fe, will put significant constraints on geochemical processes that have formed the crust and produced any later volcanism. The Neutron Spectrometer sensor on the GRNS instrument will yield estimates of the amount of H in surface materials and may ascertain if the permanently shadowed polar craters have a significant excess of H due to water ice. A comparison of the FeO content of olivine and pyroxene determined by the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) instrument with the total Fe determined through both GRNS and XRS will permit an estimate of the amount of Fe present in other forms, including metal and sulfides. © 2007 Springer Science+Business Media B.V.
Boynton, W. V., Taylor, G. J., Evans, L. G., Reedy, R. C., Starr, R., Janes, D. M., Kerry, K. E., Drake, D. M., Kim, K. J., Williams, R. M., Crombie, M. K., Dohm, J. M., Metzger, A. E., Karunatillake, S., Keller, J. M., Newsom, H. E., Arnold, J. R., Brückner, J., Englert, P. A., , Gasnault, O., et al. (2007). Concentration of H, Si, Cl, K, Fe, and Th in the low- and mid-latitude regions of Mars. Journal of Geophysical Research E: Planets, 112(12).
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Abstract: We report maps of the concentrations of H, Si, Cl, K, Fe, and Th as determined by the Gamma Ray Spectrometer (GRS) on board the 2001 Mars Odyssey Mission for ±∼45° latitudes. The procedures by which the spectra are processed to yield quantitative concentrations are described in detail. The concentrations of elements determined over the locations of the various Mars landers generally agree well with the lander values except for Fe, although the mean of the GRS Fe data agrees well with that of Martian meteorites. The water-equivalent concentration of hydrogen by mass varies from about 1.5% to 7.5% (by mass) with the most enriched areas being near Apollinaris Patera and Arabia Terra. Cl shows a distribution similar to H over the surface except that the Cl content over Medusae Fossae is much greater than elsewhere. The map of Fe shows enrichment in the northern lowlands versus the southern highlands. Silicon shows only very modest variation over the surface with mass fractions ranging from 19% to 22% over most of the planet, though a significant depletion in Si is noted in a region west of Tharsis Montes and Olympus Mons where the Si content is as low as 18%. K and Th show a very similar pattern with depletions associated with young volcanic deposits and enrichments associated with the TES Surface Type-2 material. It is noted that there appears to be no evidence of significant globally distributed thick dust deposits of uniform composition. Copyright 2007 by the American Geophysical Union.
Chamberlain, M. A., & Boynton, W. V. (2007). Response of Martian ground ice to orbit-induced climate change. Journal of Geophysical Research E: Planets, 112(6).
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Abstract: Variations in the orbit and spin axis of Mars drive climate changes that affect both surface temperatures and atmospheric water content, both of which affect the distribution of ground ice. A simple technique is presented to determine the atmospheric water content for different epochs, on the basis of the water carrying capacity of the atmosphere over surface ice. Also presented is a technique to correct the water vapor density just above the surface for depletion due to nighttime frost, reducing the effective water vapor density in contact with ground ice. Distributions of stable ground ice are generated for the present epoch with varying amounts of water vapor in the atmosphere; water vapor depletion restricts the extent of stable ground ice and ice never becomes stable at low latitudes. As the position of perihelion varies, the extent of ground ice changes several degrees in latitudinal extent. The extent of ground ice is more sensitive to obliquity; however, high obliquities are still not able to make ground ice stable at low latitudes. The finding that ice is never stable at low latitudes is consistent with the absence of ice-related landforms, like terrain softening, at low latitudes. Correlations exist between the extents of stable ground ice and the distribution of various styles of mantle deposits. Copyright 2007 by the American Geophysical Union.
E., C., Starr, R. D., Ho, G. C., Bechtold, K. E., Hamilton, S. A., Boldt, J. D., Boynton, W. V., Bradley, W., Fraeman, M. E., Gold, R. E., Goldsten, J. O., Hayes, J. R., Jaskulek, S. E., Rossano, E., Rumpf, R. A., Schaefer, E. D., Strohbehn, K., Shelton, R. G., Thompson, R. E., , Trombka, J. I., et al. (2007). The X-ray spectrometer on the MESSENGER spacecraft. Space Science Reviews, 131(1-4), 393-415.
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Abstract: NASA's MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission will further the understanding of the formation of the planets by examining the least studied of the terrestrial planets, Mercury. During the one-year orbital phase (beginning in 2011) and three earlier flybys (2008 and 2009), the X-Ray Spectrometer (XRS) onboard the MESSENGER spacecraft will measure the surface elemental composition. XRS will measure the characteristic X-ray emissions induced on the surface of Mercury by the incident solar flux. The Kα lines for the elements Mg, Al, Si, S, Ca, Ti, and Fe will be detected. The 12° field-of-view of the instrument will allow a spatial resolution that ranges from 42 km at periapsis to 3200 km at apoapsis due to the spacecraft's highly elliptical orbit. XRS will provide elemental composition measurements covering the majority of Mercury's surface, as well as potential high-spatial-resolution measurements of features of interest. This paper summarizes XRS's science objectives, technical design, calibration, and mission observation strategy. © 2007 Springer Science+Business Media B.V.
Evans, L. G., Reedy, R. C., Starr, R. D., Kerry, K. E., & Boynton, W. V. (2007). Analysis of gamma ray spectra measured by Mars Odyssey. Journal of Geophysical Research E: Planets, 112(3).
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Abstract: Gamma ray spectra measured by the Mars Odyssey gamma ray spectrometer while in orbit around Mars were analyzed to identify the sources of 334 observed peaks and features. Most peaks were of a standard Gaussian shape with a low-energy tail. However, Doppler-broadened and sawtooth-shaped peaks were also observed in the spectra. The sources of most peaks were identified. Many peaks come from the gamma ray detector material or materials around the detector, particularly Ti and Mg. Identifications were often confirmed by analyzing other spectra, such as those measured during the cruise to Mars, before and after the boom deployment, at the end of solar particle events, and over thick frozen CO2 polar caps during winters. Copyright 2006 by the American Geophysical Union.
Goldsten, J. O., Rhodes, E. A., Boynton, W. V., Feldman, W. C., Lawrence, D. J., Trombka, J. I., Smith, D. M., Evans, L. G., White, J., Madden, N. W., Berg, P. C., Murphy, G. A., Gurnee, R. S., Strohbehn, K., Williams, B. D., Schaefer, E. D., Monaco, C. A., Cork, C. P., Eckels, J. D., , Miller, W. O., et al. (2007). The MESSENGER gamma-ray and neutron spectrometer. Space Science Reviews, 131(1-4), 339-391.
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Abstract: A Gamma-Ray and Neutron Spectrometer (GRNS) instrument has been developed as part of the science payload for NASA's Discovery Program mission to the planet Mercury. Mercury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) launched successfully in 2004 and will journey more than six years before entering Mercury orbit to begin a one-year investigation. The GRNS instrument forms part of the geochemistry investigation and will yield maps of the elemental composition of the planet surface. Major elements include H, O, Na, Mg, Si, Ca, Ti, Fe, K, and Th. The Gamma-Ray Spectrometer (GRS) portion detects gamma-ray emissions in the 0.1- to 10-MeV energy range and achieves an energy resolution of 3.5 keV full-width at half-maximum for 60Co (1332 keV). It is the first interplanetary use of a mechanically cooled Ge detector. Special construction techniques provide the necessary thermal isolation to maintain the sensor's encapsulated detector at cryogenic temperatures (90 K) despite the intense thermal environment. Given the mission constraints, the GRS sensor is necessarily body-mounted to the spacecraft, but the outer housing is equipped with an anticoincidence shield to reduce the background from charged particles. The Neutron Spectrometer (NS) sensor consists of a sandwich of three scintillation detectors working in concert to measure the flux of ejected neutrons in three energy ranges from thermal to ∼ 7 MeV. The NS is particularly sensitive to H content and will help resolve the composition of Mercury's polar deposits. This paper provides an overview of the Gamma-Ray and Neutron Spectrometer and describes its science and measurement objectives, the design and operation of the instrument, the ground calibration effort, and a look at some early in-flight data. © 2007 Springer Science+Business Media B.V.
Hahn, B. C., McLennan, S. M., Taylor, G. J., Boynton, W. V., Dohm, J. M., Finch, M. J., Hamara, D. K., Janes, D. M., Karunatillake, S., Keller, J. M., Kerry, K. E., Metzger, A. E., & Williams, R. M. (2007). Mars Odyssey Gamma Ray Spectrometer elemental abundances and apparent relative surface age: Implications for Martian crustal evolution. Journal of Geophysical Research E: Planets, 112(3).
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Abstract: Quantifying secular variations in the chemical composition of the Martian crust provides unique insights into the processes that have guided the evolution of the Martian crust-mantle system. Using global abundances for a suite of elements determined by the Gamma Ray Spectrometer (GRS) on board the Mars Odyssey spacecraft and global mapping of apparent surface age adapted from existing geologic maps in the USGS Martian Geologic Investigation series, we report the average abundance of K, Th, Fe, Cl, H, and Si for the major Martian geologic epochs (Noachian, Hesperian, and Amazonian). Average GRS-determined K and Th abundances generally decrease by 9% and 7%, respectively, between the Hesperian and the Amazonian, possibly implying evolving magma chemistry throughout major resurfacing events (although the effects of surficial alteration processes cannot be entirely discounted). GRS-determined Fe and Cl averages increase by 12% and 19%, respectively, with younger apparent relative surface age, suggesting the possible mobilization and transport of these elements through aqueous processes (although an igneous origin for the variation in Fe also cannot be excluded). While H abundance does vary with surface age, the relationship is likely not governed by geologic processes. No statistically reliable apparent surface age relation was found for Si. Copyright 2007 by the American Geophysical Union.
Karunatillake, S., Keller, J. M., Squyres, S. W., Boynton, W. V., Brückner, J., Janes, D. M., Gasnault, O., & Newsom, H. E. (2007). Chemical compositions at Mars landing sites subject to Mars Odyssey Gamma Ray Spectrometer constraints. Journal of Geophysical Research E: Planets, 112(8).
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Abstract: The Mars Odyssey Gamma Ray Spectrometer (GRS) is the first instrument suite to return elemental abundances throughout the midlatitudes of Mars. Concentrations of Cl, Fe, H, K, Si, and Th have been determined to tens of centimeter depths as mass fractions with reasonable confidence. Comparing such data with, or normalizing them to, in situ compositional data is difficult due to issues such as dramatic differences in spatial resolution; difficulties in convolving densities, abundances, and compositions of different regolith components; and a limited number of elements observed in common. We address these concerns in the context of the GRS, using Si at Pathfinder to normalize remote data. In addition, we determine representative in situ compositions for Spirit (both with and without Columbia Hills rocks), Opportunity, and Viking 1 landing sites using GRS-derived H content to hydrate the soil component. Our estimate of the Si mass fraction at Pathfinder, with 13% areal fraction of rocks, is 21%. The composition of major elements, such as Si and Fe, is similar across the four landing sites, while minor elements show significant variability. Areal dominance of soil at all four landing sites causes representative compositions to be driven by the soil component, while proportionally large uncertainties of bulk densities dominate the net uncertainties. GRS compositional determinations compare favorably with the in situ estimates for Cl and K, and for Si by virtue of the normalization. However, the GRS-determined Fe content at each landing site is consistently higher than the in situ value. Copyright 2007 by the American Geophysical Union.
Karunatillake, S., Squyres, S. W., Taylor, G. J., Keller, J. M., Gasnault, O., Evans, L. G., Reedy, R. C., Starr, R. D., Boynton, W. V., Janes, D. M., Kerry, K. E., Dohm, J. M., Sprague, A. L., Hahn, B. C., & Hamara, D. (2007). Composition of northern low-albedo regions of Mars: Insights from the Mars Odyssey Gamma Ray Spectrometer. Journal of Geophysical Research E: Planets, 112(3).
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Abstract: Analysis of data acquired by the Mars Global Surveyor Thermal Emission Spectrometer (TES) instrument led to the identification of two distinct surface types. "Surface type 1," lying mostly within southern low-albedo terrain, is likely to be composed of basalt. However, there are several competing mineralogical models for "surface type 2," which is found primarily in northern low-albedo terrain. We attempt to identify which models better agree with element concentrations determined through the Gamma Subsystem (GS) of the Gamma Ray Spectrometer (GRS) instrument suite aboard the Mars Odyssey spacecraft. We have binned GS data over threshold regions derived from maps of surface types 1 and 2 and examined the spatial correlation of element concentrations with surface type 2. The elements we have examined are Cl, Fe, H, K, Si, and Th. Our results show that K concentration, Th concentration, and the areal abundance of surface type 2 are strongly correlated, with significant enrichment of both K and Th in regions representative of surface type 2. In addition, Si does not appear to be significantly enriched in surface type 2. These results are more consistent with surface type 2 originating from a compositionally distinct mantle source than the aqueous alteration of basalts. Copyright 2006 by the American Geophysical Union.
Kelly, N. J., Boynton, W. V., Kerry, K. E., Hamara, D., Janes, D. M., Reddy, R. C., Kim, K. J., & Haberle, R. M. (2007). Seasonal polar carbon dioxide frost on Mars: CO₂ mass and columnar thickness distribution. Journal of Geophysical Research E: Planets, 112(3).
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Abstract: Conclusions are drawn about the column density (g/cm2), spatial extent, and mass of the seasonal carbon dioxide frost on the poles of Mars as a function of time utilizing data from the 2001 Mars Odyssey Gamma Ray Spectrometer (GRS). Quantification of these CO2 values is achieved by observing attenuation effects of the surface-emitted hydrogen gamma ray flux as the frost condenses and sublimates in a seasonal exchange of CO2 between the ground and the atmosphere. Columnar thickness and mass results are discussed and plotted for latitudes including ±60° and poleward. GRS observations are compared to predictions from the NASA Ames Research Center General Circulation Model and to similar experimental results from the Mars Odyssey High Energy Neutron Detector and Neutron Spectrometer. Models for north and south polar atmosphere and regolith distributions are incorporated, and our results indicate that the assumption of a 100% H2O-ice residual cap underlying the seasonal frost in the north is accurate. The GRS CO2 frost observations are in good agreement with the other studies mentioned, in particular for the timing of the beginning of frost deposition to the complete sublimation of surface CO2 back into the atmosphere. The total amount of condensed carbon dioxide mass seen by the GRS is on the order of 6.0 × 1015 kg and verifies previous reports that nearly 25% of the Martian CO2 reservoir participates in the ground-atmosphere exchange cycle. Copyright 2006 by the American Geophysical Union.
Kim, K. J., Drake, D. M., Reedy, R. C., Williams, R. M., & Boynton, W. V. (2007). Theoretical fluxes of gamma rays from the Martian surface. Journal of Geophysical Research E: Planets, 112(3).
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Abstract: Theoretical fluxes of gamma rays escaping the surface of Mars were calculated. These and other calculated fluxes are needed to model the counting rates in the Mars Odyssey gamma ray spectrometer that are used to determine elemental compositions and other results using these measurements. Cross sections for the formation of gamma rays by both thermal and fast neutrons were compiled and evaluated. These evaluated cross sections were used with neutron fluxes calculated with the Monte Carlo N Particle Extended (MCNPX) code to get gamma ray production rates as a function of depth in the Martian surface. The fluxes of these gamma rays as a function of angle at the Martian surface were then calculated using gamma ray attenuation coefficients. Copyright 2006 by the American Geophysical Union.
Kuzmin, R. O., Zabalueva, E. V., Mitrofanov, I. G., Litvak, M. L., Rodin, A. V., Boynton, W. V., & Saunders, R. S. (2007). Seasonal redistribution of water in the surficial Martian regolith: Results from the Mars Odyssey high-energy neutron detector (HEND). Solar System Research, 41(2), 89-102.
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Abstract: The seasonal variation of neutron emissions from Mars in different spectral intervals measured by the HEND neutron detector for the entire Martian year are analyzed. Based on these data, the spatial variations of the neutron emissions from the planet are globally mapped as a function of season, and the dynamics of seasonal variation of neutron fluxes with different energies is analyzed in detail. No differences were found between seasonal regimes of neutron fluxes in different energy ranges in the southern hemisphere of Mars, while the regime of fast neutrons (with higher energies) during the northern winter strongly differs from that during the southern winter. In winter (L s = 270°-330°), the fast neutron fluxes are noticeably reduced in the northern hemisphere (along with the consecutive thickening of the seasonal cap of solid carbon dioxide). This provides evidence of a temporary increase in the water content in the effective layer of neutron generation. According to the obtained estimates, the observed reduction of the flux of fast neutrons in the effective layer corresponds to an increase in the water abundance of up to 5% in the seasonal polar cap (70°-90°N), about 3% at mid-latitudes, and from 1.5 to 2% at low latitudes. The freezing out of atmospheric water at the planetary surface (at middle and high latitudes) and the hydration of salt minerals composing the Martian soil are considered as the main processes responsible for the temporary increase in the water content in the soil and upper layer of the seasonal polar cap. The meridional atmospheric transport of water vapor from the summer southern to the winter northern hemisphere within the Hadley circulation cell is a basic process that delivers water to the subsurface soil layer and ensures the observed scale of the seasonal increase in water abundance. In the summer northern hemisphere, the similar Hadley circulation cell transports mainly dry air masses to the winter southern hemisphere. The point is that the water vapor becomes saturated at lower heights during aphelion, and the bulk of the atmospheric water mass is captured in the near-equatorial cloudy belt and, thus, is only weakly transferred to the southern hemisphere. This phenomenon, known as the Clancy effect, was suggested by Clancy et al. (1996) as a basic mechanism for the explanation of the interhemispheric asymmetry of water storage in permanent polar caps. The asymmetry of seasonal meridional circulation of the Martian atmosphere seems to be another factor determining the asymmetry of the seasonal water redistribution in the "atmosphere-regolith-seasonal polar caps" system, found in the peculiarities of the seasonal regime of the neutron emission of Mars. © Nauka/Interperiodica 2007.
Litvak, M. L., Mitrofanov, I. G., Kozyrev, A. S., Sanin, A. B., Tret'yakov, V., Boynton, W. V., Hamara, D., & Saunders, S. (2007). Long-term observations of the evolution of the southern seasonal cap of Mars: Neutron measurements by the HEND instrument onboard the 2001 Mars Odyssey spacecraft. Solar System Research, 41(5), 385-394.
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Abstract: We present the results of five-year observations of the southern seasonal cap of Mars based on neutron spectroscopy of the surface fulfilled by the Russian HEND instrument onboard the NASA 2001 Mars Odyssey spacecraft. The numerical modeling of the observational data allowed us to reconstruct the curves of the variations of the total mass of the southern seasonal cap of Mars for different years (three Martian years) and to find the year-to-year variations of the seasonal cycle. © 2007 Pleiades Publishing, Inc.
Litvak, M. L., Mitrofanov, I. G., Kozyrev, A. S., Sanin, A. B., Tretyakov, V. I., Boynton, W. V., Kelly, N. J., Hamara, D., & Saunders, R. S. (2007). Long-term observations of southern winters on Mars: Estimations of column thickness, mass, and volume density of the seasonal CO₂ deposit from HEND/Odyssey data. Journal of Geophysical Research E: Planets, 112(3).
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Abstract: In this paper, we have analyzed neutron spectroscopy data gathered by the High Energy Neutron Detector (HEND) instrument on board Mars Odyssey for two Martian years of orbital mapping. We focused on the observations of the Martian southern seasonal cap for this period of time. Nuclear methods based on numerical modeling allow us to derive an estimation of the distribution of CO2 frost column density and mass from the temporal variations of neutron flux between summer and winter seasons. We have estimated the seasonal behavior of both the column density and mass of CO2 frost. Comparison between two Martian years revealed minor (
Luhmann, J. G., Zeitlin, C., Turner, R., Brain, D. A., Delory, G., Lyon, J. G., & Boynton, W. (2007). Solar energetic particles in near-Mars space. Journal of Geophysical Research E: Planets, 112(10).
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Abstract: The space radiation environment near Mars has taken on new interest due to the resurrection of plans to send humans to explore the red planet. In addition, solar energetic particles represent a possibly significant input of energy to the atmosphere of Mars during major events, with consequences for atmospheric ionization, chemistry, and possibly escape. Measurements of solar events by the MARIE and GRS experiments on Mars Odyssey illustrate how Mars affects the low-Mars-orbit fluxes of these particles, apparently blocking some particles' access to the spacecraft. The extent to which the presence of Mars reduces the fluxes in Mars orbit from their interplanetary values, and the circumstances and geometry of those reductions, is examined using a simple model and some observationally inspired assumptions about the nature of solar energetic particle events. The results suggest how Mars orbiter SEP results can be interpreted, and also how near-Mars fluxes for a particular interplanetary event can be predicted. Copyright 2007 by the American Geophysical Union.
Mitrofanov, I. G., Zuber, M. T., Litvak, M. L., Demidov, N. E., Sanin, A. B., Boynton, W. V., Gilichinsky, D. A., Hamara, D., Kozyrev, A. S., Saunders, R. D., Smith, D. E., & Tretyakov, V. I. (2007). Water ice permafrost on Mars: Layering structure and subsurface distribution according to HEND/Odyssey and MOLA/MGS data. Geophysical Research Letters, 34(18).
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Abstract: To elucidate the nature of permafrost in the shallow subsurface of Mars, we analyze jointly neutron albedo from the High Energy Neutron Detector (HEND) on the Mars Odyssey spacecraft and near-IR (1064-nm) surface reflectance from the Mars Orbiter Laser Altimeter (MOLA) on Mars Global Surveyor. The first dataset measures the content of hydrogen (in the form of water or hydroxyl) in the soil, and the second yields the flux of absorbed solar energy by the surface. We identify a statistically - significant negative cross-correlation between these data at latitudes poleward of 40° latitude in the northern hemisphere and in the latitude band 40°-60° in the southern hemisphere, which we interpret as evidence for the presence of stable water ice under a dry equilibrium top layer (ETL). We deduce an empirical relation between near-IR reflectance and thickness of this ETL, which allows the burial depth of the water ice table to be estimated with km-scale spatial resolution. We observe no correlation between neutron and near-IR albedo within the southern hemisphere poleward of 60° latitude. While it is known from previously analyzed neutron and gamma-ray data that subsurface water ice is present within this region and is covered by a layer of dry regolith, the absence of a correlation indicates that the thickness of this layer is not controlled by an equilibrium condition between the ice table and atmosphere. Copyright 2007 by the American Geophysical Union.
Nelli, S. M., Murphy, J. R., Sprague, A. L., Boynton, W. V., Kerry, K. E., Janes, D. M., & Metzger, A. E. (2007). Dissecting the polar dichotomy of the noncondensable gas enhancement on Mars using the NASA Ames Mars General Circulation Model. Journal of Geophysical Research E: Planets, 112(8).
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Abstract: The atmospheric processes underlying the observed spatial and temporal enhancement of noncondensing gases in Mars' atmosphere are investigated. The Gamma Ray Spectrometer (GRS) on board Mars Odyssey has obtained measurements indicating that the absolute and relative column abundance of noncondensing gases (primarily argon and nitrogen) maximizes at high latitudes in both hemispheres during winter as CO2 gas condenses and forms the seasonal polar ice cap. This condensing CO2 "leaves behind" noncondensing gases whose local absolute and relative column abundances can increase at a rate controlled by mixing with less-enhanced air from lower latitudes. Understanding the processes responsible for the magnitude and seasonal variations of these enhancement values is an aid in understanding atmospheric transport processes. The NASA Ames Mars General Circulation Model is employed to help understand the atmospheric thermodynamical mechanisms that give rise to the observed temporal and magnitude variations in the polar enhancement values. The model produces a threefold noncondensable gas enhancement in the south polar region and an approximate 1.4-fold increase in noncondensables in the north polar region. These model results are temporally consistent with observed values, but the observed enhancement magnitudes exceed those modeled by up to a factor of two. The difference in strength and the season of formation between transient eddies in the southern and northern hemispheres may play a large role in determining the different character of the two polar enhancements. Model simulations also illuminate the effect that topography, orbital eccentricity, and atmospheric st opacity have on producing the north versus south polar enhancement dichotomy. Copyright 2007 by the American Geophysical Union.
Newsom, H. E., Crumpler, L. S., Reedy, R. C., Petersen, M. T., Newsom, G. C., Evans, L. G., Taylor, G. J., Keller, J. M., Janes, D. M., Boynton, W. V., Kerry, K. E., & Karunatillake, S. (2007). Geochemistry of Martian soil and bedrock in mantled and less mantled terrains with gamma ray data from Mars Odyssey. Journal of Geophysical Research E: Planets, 112(3).
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Abstract: Surficial materials, including soil and dust, are abundant in the upper tens of centimeters of the Martian surface sensed by the Mars Odyssey Gamma Ray Spectrometer (GRS). Seven large areas (14% of the Martian surface) that represent possible compositional end-members were selected, including three regions heavily mantled with surficial materials. The selection process included mapping the ratio of exposed rocky terrain to surficial materials using high-resolution imagery. GRS data for H, Cl, Fe, Si, K, and Th were obtained for each area. The areas are chemically homogeneous within each area, given the spatial resolution and analytical uncertainty of the GRS data. However, substantial chemical differences exist among the areas, including the different mantled terrains, contrary to earlier assumptions that surficial materials are globally homogeneous due to aeolian mixing. The observed chemical differences among the areas may be due to variations in the protolith compositions, extent of alteration of the protolith regions, or post soil formation processes. The abundances of Cl, K, and Th in rockier (but still soil-rich) areas such as Syrtis Major Planum can be explained by mixing between a soil with higher concentrations of Cl, K, and Th, similar to the abundances in the mantled terrains (and some of the landing sites), and crustal rocks containing lower abundances of these elements, similar to Martian meteorites. Copyright 2007 by the American Geophysical Union.
Sprague, A. L., Boynton, W. V., Kerry, K. E., Janes, D. M., Kelly, N. J., Crombie, M. K., Nelli, S. M., Murphy, J. R., Reddy, R. C., & Metzger, A. E. (2007). Mars' atmospheric argon: Tracer for understanding Martian atmospheric circulation and dynamics. Journal of Geophysical Research E: Planets, 112(3).
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Abstract: One and one half Mars years, from 8 June 2002 to 2 April 2005, of atmospheric argon (Ar) measurements are described and studied in the context of understanding how Ar, a minor constituent of the Martian atmosphere that does not condense at temperatures found on Mars, can be used to study Martian circulation and dynamics. The Ar data are from the gamma subsystem of the gamma ray spectrometer currently operating on the Mars Odyssey spacecraft in orbit around Mars. A comprehensive data analysis including γ ray production and attenuation by the atmosphere is presented. Four discoveries are discussed. (1) There is a factor of 6 enhancement of Ar measured over south polar latitudes (75°S to 90°S) for 2 consecutive Mars years occurring near the onset of southern winter. (2) There is no similar strong enhancement of Ar over north polar regions during northern winter. Part of this difference is explained by the global topographic dichotomy and the fact that the duration of northern autumn and winter is only ∼80% as long as that of southern autumn and winter. (3) Rapid seasonal fluctuations in Ar abundance from 60°S to 90°S may be evidence for wave activity at the perimeter of the southern seasonal polar cap. (4) The magnitude of the Ar enhancement over the south polar region lacks spatial coincidence with either the relatively dark "cryptic terrain" or the relatively bright albedo regions; however, a divergence in Ar abundance near Ls = 267.5° may be an expression of later CO2 sublimation in the bright terrain rather than in the cryptic region. Copyright 2007 by the American Geophysical Union.
Basilevsky, A. T., Rodin, A. V., Raitala, J., Neukum, G., Werner, S., Kozyrev, A. S., Sanin, A. B., Mitrofanov, I. G., Head, J. W., Boynton, W., & Saunders, R. S. (2006). Search for causes of the low epithermal neutron flux anomaly in the Arabia Terra region (Mars). Solar System Research, 40(5), 355-374.
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Abstract: A geologic analysis of 274 images acquired by the high-resolution MOC camera onboard the Mars Global Surveyor spacecraft within the Arabia Terra low neutron flux anomaly (which is indicative of an anomalously high abundance of hydrogen: up to 16 wt % of the equivalent amount of water) was performed. Correlation between the enhanced abundance of equivalent water with the presence of dust on the surface was found. Since dust plays a key role in condensation of water from the atmosphere, we suppose that the anomalies could result from the retention of atmospheric moisture. To analyze this suggestion, we performed a theoretical modeling that allowed us to map the planetary-scale distributions of several meteorological parameters responsible for the atmospheric moisture condensation. Two antipodal regions coinciding rather well with the Arabia Terra anomaly and the geographically antipodal anomaly southwest of Olympus Mons were found in the maps. This suggests that the anomalies are rather recent than ancient formations. They were probably formed by a sink of moisture from the atmosphere in the areas where present meteorological conditions support this sink. Geological parameters, primarily the presence of dust, only promote this process. We cannot exclude the possibility that the Martian cryosphere, rather than the atmosphere, supplied the studied anomalies with moisture during their formation: the thermodynamic conditions in the anomaly areas could block the moisture flux from the Martian interior in the upper regolith layer. The moisture coming from the atmosphere or from the interior is likely held as chemically bound water entering into the structure of water-bearing minerals (probably, hydrated magnesium sulfates) directly from the vapor; or the moisture precipitates as frost, penetrates into microfissures, and then is bound in minerals. Probably, another geologic factor-the magnesium sulfate abundance-works in the Arabia Terra anomaly. © Nauka/Interperiodica 2006.
Beaty, D. W., Buxbaum, K. L., Meyer, M. A., Barlow, N., Boynton, W., Clark, B., Deming, J., Doran, P. T., Edgett, K., Hancock, S., Head, J., Hecht, M., Hipkin, V., Kieft, T., Mancinelli, R., McDonald, E., McKay, C., Mellon, M., Newsom, H., , Ori, G., et al. (2006). Findings of the Mars Special Regions Science Analysis Group. Astrobiology, 6(5), 677-732.
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PMID: 17067257;Abstract: In summary, within the upper 5 m most of Mars is either too cold or too dry to support the propagation of terrestrial life. However, there are regions that are in disequilibrium, naturally or induced, and could be classified as "special" or, if enough uncertainty exist, could not be declared as "non-special." © Mary Ann Liebert, Inc.
F., A., Johnson, J. B., Elphic, R. C., Boynton, W. V., & Wetzel, J. (2006). Construction and Resource Utilization eXplorer (CRUX): Implementing instrument suite data fusion to characterize regolith hydrogen resources. IEEE Aerospace Conference Proceedings, 2006.
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Abstract: CRUX is a modular suite of geophysical and borehole instruments combined with display and decision support system (Mapper/DSS) tools to characterize regolith resources, surface conditions, and geotechnical properties. CRUX is a NASA-funded Technology Maturation Program effort to provide enabling technology for Lunar and Planetary Surface Operations (LPSO) [1]. The Mapper/DSS uses data fusion methods with CRUX instruments, and other available data and models, to provide regolith properties information needed for LPSO that cannot be determined otherwise. We demonstrate the data fusion method by showing how it might be applied to characterize the distribution and form of hydrogen using a selection of CRUX instruments: Borehole Neutron Probe and Thermal Evolved Gas Analyzer data as a function of depth help interpret Surface Neutron Probe data to generate 3D information. Secondary information from other instruments along with physical models improves the hydrogen distribution characterization, enabling information products for operational decision-making. © 2006 IEEE.
Hurley, K., Mitrofanov, I., Charyshnikov, S., Grinkov, V., Kozyrev, A., Litvak, M., Sanin, A., Boynton, W., Fellows, C., Harshman, K., Shinohara, C., & Starr, R. (2006). The Mars Odyssey experiments in the third interplanetary network. Advances in Space Research, 38(7), 1312-1315.
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Abstract: The Mars Odyssey spacecraft carries two experiments which are capable of detecting cosmic gamma-ray bursts and soft gamma repeaters. Since April 2001 they have detected approximately 200 bursts and, in conjunction with the other spacecraft of the interplanetary network, localized many of them rapidly and precisely enough to allow sensitive multi-wavelength counterpart searches. We present the Mars Odyssey mission and describe the two experiments. © 2005 COSPAR.
Hurley, K., Mitrofanov, I., Kozyrev, A., Litvak, M., Sanin, A., Grinkov, V., Charyshnikov, S., Boynton, W., Fellows, C., Harshman, K., Hamara, D., Shinohara, C., Starr, R., & Cline, T. (2006). Mars Odyssey joins the third interplanetary network. Astrophysical Journal, Supplement Series, 164(1), 124-129.
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Abstract: The Mars Odyssey spacecraft carries two experiments that are capable of detecting cosmic gamma-ray bursts and soft gamma repeaters. Since 2001 April they have detected over 275 bursts and, in conjunction with the other spacecraft of the interplanetary network, localized many of them rapidly and precisely enough to allow sensitive multiwavelength counterpart searches. We present the Mars Odyssey mission and describe the burst capabilities of the two experiments in detail. We explain how the spacecraft timing and ephemeris have been verified in-flight using bursts from objects whose precise positions are known by other means. Finally, we show several examples of localizations and discuss future plans for the Odyssey mission and the network as a whole. © 2006. The American Astronomical Society. All rights reserved.
Johnson, J. B., F., A., Elphic, R. C., Boynton, W. V., Wetzel, J., & Jensen, H. (2006). Data fusion methods applied to the Construction and Resource Utilization eXplorer (CRUX) instruments to characterize regolith hydrogen resources. Earth and Space 2006 - Proceedings of the 10th Biennial International Conference on Engineering, Construction, and Operations in Challenging Environments, 2006, 68-.
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Abstract: CRUX is a suite of modular geophysical and borehole instruments combined with a display and decision support system (Mapper/DSS) to characterize regolith resources, surface conditions, and geotechnical properties. CRUX is a NASA-funded Technology Maturation Program effort to provide enabling technology for Lunar and Planetary Surface Operations (LPSO). The Mapper/DSS uses data fusion methods with CRUX instruments, and other available data and models, to provide information about regolith properties needed for LPSO that cannot be determined otherwise. We demonstrate how the data fusion method might be applied to characterize the form of hydrogen and its 3D distribution using a Borehole Neutron Probe and Thermal Evolved Gas Analyzer data as a function of depth to help interpret Surface Neutron Probe data. Information from other CRUX instruments, along with physical models, improves the accuracy of hydrogen distribution characterization, enabling information products for operational decision-making. Copyright ASCE 2006.
Litvak, M. L., Mitrofanov, I. G., Kozyrev, A. S., Sanin, A. B., Tretyakov, V. I., Boynton, W. V., Kelly, N. J., Hamara, D., Shinohara, C., & Saunders, R. S. (2006). Comparison between polar regions of Mars from HEND/Odyssey data. Icarus, 180(1), 23-37.
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Abstract: In this paper, we have analyzed neutron spectroscopy data gathered by the High Energy Neutron Detector (HEND) instrument onboard Mars Odyssey for comparison of polar regions. It is known that observation of the neutron albedo of Mars provides important information about the distribution of water-ice in subsurface layers and about peculiarities of the CO2 seasonal cycle. It was found that there are large water-rich permafrost areas with contents of up to ∼50% water by mass fraction at both the north and south Mars polar regions. The water-ice layers at high northern latitudes are placed close to the surface, but in the south they are covered by a dry and relatively thick (10-20 cm) layer of soil. Analysis of temporal variations of neutron flux between summer and winter seasons allowed the estimation of the masses of the CO2 deposits which seasonally condense at the polar regions. The total mass of the southern seasonal deposition was estimated as 6.3 × 1015 kg, which is larger than the total mass of the seasonal deposition at the north by 40-50%. These results are in good agreement with predictions from the NASA Ames Research Center General Circulation Model (GCM). But, the dynamics of the condensation and sublimation processes are not quite as consistent with these models: the peak accumulation of the condensed mass of CO2 occurred 10-15 degrees of Ls later than is predicted by the GCM. © 2005 Elsevier Inc. All rights reserved.
Lorenz, R. D., Boynton, W. V., & Turner, C. (2006). Demonstration of comet sample collection by penetrator. Acta Astronautica, 59(8-11), 1000-1007.
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Abstract: We describe laboratory tests to investigate and demonstrate the acquisition and encapsulation of a subsurface sample from a comet analogue using a coring penetrator. The penetrator imbeds itself in the target, coring out a sample during the impact itself. Mechanisms seal the sample in a canister and the canister is spring-ejected from the rear of the penetrator where it can be retrieved in free-flight by a mother spacecraft, which thus need not perform a landing. We describe the penetrator vehicle, sample preparation and testing technique using the large airgun at the University of Arizona, and the performance results which indicate the technique is an attractive option for comet nucleus sample return. © 2005 Elsevier Ltd. All rights reserved.
Morgan, D. D., Gurnett, D. A., Kirchner, D. L., Huff, R. L., Brain, D. A., Boynton, W. V., Acuña, M., Plaut, J. J., & Picardi, G. (2006). Solar control of radar wave absorption by the Martian ionosphere. Geophysical Research Letters, 33(13).
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Abstract: The MARSIS active sounder aboard the Mars Express spacecraft, under certain conditions in the Martian ionosphere, fails to detect the planetary surface. We have generated a statistical measure of the surface reflection visibility, which we plot as a time series and compare with both in situ particle data taken at Mars and solar x-ray data taken at Earth. We show that loss of the surface signal is closely related to the influx of solar protons at tens of MeV energies. We infer that the influx of high energy solar protons causes impact ionization, increasing the electron density in the Martian ionosphere. At altitudes close to or below 100 km, where the electron-neutral collision frequency is high and the electron density typically has a local maximum, the increased electron density raises the damping coefficient to levels sufficient for complete absorption of the sounding wave over an altitude ranee of a few tens of kilometers. Copyright 2006 by the American Geophysical Union.
Sprague, A. L., Hunten, D. M., Doose, L. R., Hill, R. E., Boynton, W. V., Smith, M. D., & Pearl, J. C. (2006). Mars atmospheric water vapor abundance: 1991-1999, emphasis 1998-1999. Icarus, 184(2), 372-400.
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Abstract: Our ground-based measurements of martian atmospheric water vapor, made throughout Ls = 34 ° to 249°, 24 September 1998 to 23 November 1999, during Mars year 24 (MY 24), show changes in Mars' humidity on hourly, daily, and seasonal timescales. We made concomitant measurement of nearby CO2 bands, and when possible, results were corrected for aerosol extinction using aerosol optical depths derived from our own CO2 analysis. Where there is spatial and temporal overlap, similar results are obtained for water vapor abundances and aerosol opacities as those observed from the Thermal Emission Spectrometer on Mars Global Surveyor. In addition some further discussion of our published earlier water vapor measurements (1991-1995) is included. Six results from this data set are: (1) the measured aerosol opacity in Mars atmosphere was variable but not greater than τ = 1, with almost no clear atmosphere being observed, (2) measurements made with the slit crossing many hours of local time on Mars' Earth-facing disk show a diurnal pattern with highest abundances at mid-day and low abundance in very early morning and late afternoon for some but not all measurements, (3) water vapor abundance is patchy on hourly and daily time scales but follows the usual seasonal trends seen by instrumentation on the Mars Atmospheric Water Detector on the Viking Orbiters and by the Thermal Emission Spectrometer on Mars Global Surveyor, (4) there is a slight longitudinal correlation with the ground-ice observed by the Gamma Ray Spectrometer on Mars Odyssey, (5) there is evidence of the Low Southern Latitude Summer Minimum in our water vapor measurements but our data set for southern summer is limited, and (6) MY 24 appears to be wetter than MY 22 and MY 23. © 2006 Elsevier Inc. All rights reserved.
Hurley, K., Boggs, S. E., Smith, D. M., Duncan, R. C., Lin, R., Zoglauer, A., Krucker, S., Hurford, G., Hudson, H., Wigger, C., Hajdas, W., Thompson, C., Mitrofanov, I., Sanin, A., Boynton, W., Fellows, C., Kienlin, A. V., Lichti, G., Rau, A., & Cline, T. (2005). An exceptionally bright flare from SGR 1806-20 and the origins of short-duration γ-ray bursts. Nature, 434(7037), 1098-1103.
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PMID: 15858565;Abstract: Soft-γ-ray repeaters (SGRs) are galactic X-ray stars that emit numerous short-duration (about 0.1 s) bursts of hard X-rays during sporadic active periods. They are thought to be magnetars: strongly magnetized neutron stars with emissions powered by the dissipation of magnetic energy. Here we report the detection of a long (380 s) giant flare from SGR 1806-20, which was much more luminous than any previous transient event observed in our Galaxy. (In the first 0.2 s, the flare released as much energy as the Sun radiates in a quarter of a million years.) Its power can be explained by a catastrophic instability involving global crust failure and magnetic reconnection on a magnetar, with possible large-scale untwisting of magnetic field lines outside the star. From a great distance this event would appear to be a short-duration, hard-spectrum cosmic γ-ray burst. At least a significant fraction of the mysterious short-duration γ-ray bursts may therefore come from extragalactic magnetars.
Jakosky, B. M., Mellon, M. T., Varnes, E. S., Feldman, W. C., Boynton, W. V., & Haberle, R. M. (2005). Erratum: "Mars low-latitude neutron distribution: Possible remnant near-surface water ice and a mechanism for its recent emplacement" (Icarus) (2005) vol. 175 (58-67) 10.1016/j.icarus.2004.11.014). Icarus, 178(1), 291-293.
Jakosky, B. M., Mellon, M. T., Varnes, E. S., Feldman, W. C., Boynton, W. V., & Haberle, R. M. (2005). Mars low-latitude neutron distribution: Possible remnant near-surface water ice and a mechanism for its recent emplacement. Icarus, 175(1), 58-67.
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Abstract: The Mars Odyssey Gamma-Ray Spectrometer/Neutron Spectrometer/High Energy Neutron Detector has provided measurements of near-surface hydrogen, generally interpreted as resulting from water, in the equatorial and mid-latitudes. Water abundances as great as 10% by mass are inferred. Although such high abundances could be present as adsorbed water in clays or water of hydration of magnesium salts, other measurements suggest that this is not likely. The spatial pattern of where the water is located is not consistent with a dependence on composition, topography, present-day atmospheric water abundance, latitude, or thermophysical properties. The zonal distribution of water shows two maxima and two minima, which is very reminiscent of a distribution that is related to an atmospheric phenomenon. We suggest that the high water abundances could be due to transient ground ice that is present in the top meter of the surface. Ice would be stable at tens-of-centimeters depth at these latitudes if the atmospheric water abundance were more than about several times the present value, much as ice is stable poleward of about ±60° latitude for current water abundances. Higher atmospheric water abundances could have resulted relatively recently, even with the present orbital elements, if the south-polar cap had lost its annual covering of CO2 ice; this would have exposed an underlying water-ice cap that could supply water to the atmosphere during southern summer. If this hypothesis is correct, then (i) the low-latitude water ice is unstable today and is in the process of sublimating and diffusing back into the atmosphere, and (ii) the current configuration of perennial CO2 ice being present on the south cap but not on the north cap might not be representative of the present epoch over the last, say, ten thousand years. © 2004 Elsevier Inc. All rights reserved.
Litvak, M. L., Mitrofanov, I. G., Kozyrev, A. S., Sanin, A. B., Tretyakov, V. I., Boynton, W. V., Hamara, D., Shinohara, C., & Saunders, R. S. (2005). Modeling of Martian seasonal caps from HEND/ODYSSEY data. Advances in Space Research, 36(11), 2156-2161.
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Abstract: In this paper, we have analyzed neutron spectroscopy data gathered by the high energy neutron detector instrument onboard Mars Odyssey in order to study the behavior of CO2 condensed mass at the polar regions of Mars. It is known that observation of the neutron albedo of Mars provides not only information on distribution of water ice/bounded water through Martian subsurface but is also sensitive to the condensation/sublimation of atmospheric CO2 at the Martian poles. Analysis of temporal variations of neutron flux between summer and winter seasons allowed the creation of multidimensional model of CO2 deposition describing behavior of CO2 condensed mass as a function of longitude, latitude and time. Based on this model, we have estimated the total masses of north seasonal cap ((3.8 ± 0.4) × 1015 kg), south seasonal cap ((6.3 ± 0.6) × 1015 kg) and compared our estimations with predictions of General Circulation Model. Furthermore, using the data gathered during second Martian year on the orbit, we have conducted preliminary comparison between seasonal cycles of two successive Martian years. © 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.
Livshits, M. A., Chernetskiǐ, V., Mitrofanov, I. G., Kozyrev, A. S., Litvak, M. L., Sanin, A. B., Tret'yakov, V., Boynton, W., Shinohara, K., & Hamara, D. (2005). Hard X-ray and gamma-ray flares on the Sun: Stereoscopic effects near the limb from observations on the 2001 Mars Odyssey spacecraft and near-earth spacecraft. Astronomy Reports, 49(11), 916-931.
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Abstract: We present the first results of data on solar flares detected by the HEND instrument onboard the 2001 Mars Odyssey interplanetary spacecraft during its flight to Mars and in orbit around Mars. The instruments carried by the spacecraft, which was developed at the Space Research Institute of the Russian Academy of Sciences, included a scintillation detector with two crystals, enabling the detection of photons with energies from tens of keV to 2.5 MeV with high time resolution. Several dozen flares were detected on both the sides visible from the Earth and back side of the Sun, supplementing other available data in a number of cases. A joint analysis of the HEND data together with data obtained in near-Earth orbits enabled the detection of variations in the integrated fluxes of photons with energies exceeding 80 keV during observations of flares near the limb from various directions. Two events were analyzed in great detail: the setting of a region displaying frequent very short flares on May 20, 2001, and the rising of the group 10486, which displayed numerous flare phenomena on the limb followed by extremely high activity in October-November 2003. These variations appear in simultaneous observations of limb M flares made at angles differing by only 8°-10°. Analyses of observations of rising sources obtained on two spacecraft lead to similar results. This indicates that the vast majority of emission at energies exceeding 80 keV arises at altitudes of no higher than seven to ten thousand kilometers. We briefly consider the powerful solar-disk gamma-ray flare of August 25, 2001. In this case, there are some differences in the behavior of the hard radiation in the decay phase for observations made at angles differing by 25°, which is most likely due to differences in the instrumental responses to radiation with this spectrum. The absence of hard radiation at great heights in the region of the "cusp" places some constraints on our picture of the physical processes occurring in powerful solar flares. © 2005 Pleiades Publishing, Inc.
Patzer, A., Schlüter, J., Schultz, L., Hill, D. H., & Boynton, W. V. (2005). The new polymict eucrite Dar al Gani 983: Petrography, chemical composition, noble gas record, and evolution. Meteoritics and Planetary Science, 40(6), 869-879.
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Abstract: Mineralogical and chemical studies of Dar at Gani 983 show that this meteorite is a eucrite. Its texture is that of an impact breccia. It contains cumulate pyroxene and feldspar megacrysts, a variety of recrystallized melt clasts, clasts of subophitic basalt, and mesostasis. These components are embedded in a matrix of fragmental pyroxene and plagioclase. In addition, the entire rock is penetrated by glassy melt veins and patches, and displays features of strong shock. The mineralogical and chemical evidence obtained for DaG 983 indicates that this meteorite experienced a complex evolutionary history. The presence of cumulate silicate crystals implies substantial, large scale cratering events on the HED asteroid. As a result of these impacts, rocks from different intrusive bodies to extrusive surface layers were laterally and vertically transported to form a thoroughly mixed megaregolith. DaG 983 represents a sample of this megabrecia. © The Meteoritical Society, 2005.
Boynton, W. V., Feldman, W. C., Mitrofanov, I. G., Evans, L. G., Reedy, R. C., Squyres, S. W., Starr, R., Trombka, J. I., D'Uston, C., Arnold, J. R., Englert, P. A., Metzger, A. E., Wänke, H., Brückner, J., Drake, D. M., Shinohara, C., Fellows, C., Hamara, D. K., Harshman, K., , Kerry, K., et al. (2004). The Mars Odyssey Gamma-Ray Spectrometer instrument suite. Space Science Reviews, 110(1-2), 37-83.
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Abstract: The Mars Odyssey Gamma-Ray Spectrometer is a suite of three different instruments, a gamma subsystem (GS), a neutron spectrometer, and a high-energy neutron detector, working together to collect data that will permit the mapping of elemental concentrations on the surface of Mars. The instruments are complimentary in that the neutron instruments have greater sensitivity to low amounts of hydrogen, but their signals saturate as the hydrogen content gets high. The hydrogen signal in the GS, on the other hand, does not saturate at high hydrogen contents and is sensitive to small differences in hydrogen content even when hydrogen is very abundant. The hydrogen signal in the neutron instruments and the GS have a different dependence on depth, and thus by combining both data sets we can infer not only the amount of hydrogen, but constrain its distribution with depth. In addition to hydrogen, the GS determines the abundances of several other elements. The instruments, the basis of the technique, and the data processing requirements are described as are some expected applications of the data to scientific problems.
Boynton, W., Janes, D., Kerry, K., Kim, K., Reedy, R., Evans, L., Starr, R., Drake, D., Taylor, J., & Wänke, H. (2004). Maps of elemental abundances on the surface of Mars. Meteoritics and Planetary Science, 39(SUPPL.), A16.
Feldman, W. C., Prettyman, T. H., Maurice, S., Plaut, J. J., Bish, D. L., Vaniman, D. T., Mellon, M. T., Metzger, A. E., Squyres, S. W., Karunatillake, S., Boynton, W. V., Elphic, R. C., Funsten, H. O., Lawrence, D. J., & Tokar, R. L. (2004). Global distribution of near-surface hydrogen on Mars. Journal of Geophysical Research E: Planets, 109(9), E09006 1-13.
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Abstract: Neutron data observed using the Neutron Spectrometer aboard 2001 Mars Odyssey provide a lower limit to the global inventory of Martian water-equivalent hydrogen. Hydrogen-rich deposits ranging between about 20% and 100% water-equivalent by mass are found poleward of 4-50°latitude, and less rich, but significant, deposits are found at near-equatorial latitudes. The equatorial deposits between +45° latitude range between 2% and 10% water-equivalent hydrogen by mass and reach their maximum in two regions that straddle the 0-km elevation contour. Higher water abundances, up to ∼11%, are required in subsurface regolith of some equatorial regions if the upper 10 g/cm 2 of regolith is desiccated, as suggested on average by comparison of epithermal and fast neutron data. The hydrogen contents of surface soils in the latitude range between 50°and 80°north and south are equal within data uncertainties. A lower-limit estimate of the global inventory of near surface hydrogen amounts to a global water layer about 14 cm thick if the reservoir sampled from orbit is assumed to be 1 m thick. Copyright 2004 by the American Geophysical Union.
Kuzmin, R. O., Zabalueva, E. V., Mitrofanov, I. G., Litvak, M. L., Boynton, W. V., & Saunders, R. S. (2004). Regions of potential existence of free water (ice) in the near-surface Martian ground: Results from the Mars Odyssey high-energy neutron detector (HEND). Solar System Research, 38(1), 1-11.
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Abstract: We report results of the analysis of the data on global mapping of neutron fluxes from the Martian surface, which have been obtained during the first ten months of measurements carried out by the Russian high-energy neutron detector HEND mounted aboard the American Mars Odyssey orbiter. This analysis allowed us to separate regions where free water (in ice form) prevailed in the surface layer (with a thickness of up to 2 m) of the Martian ground from regions where physically and chemically bound ground water was most likely to be the dominant form of water. The global mapping of regions with increased ice content in the ground-surface layer revealed a direct correlation with regions of polygonal terrains morphologically similar to terrestrial polygonal forms of permafrost origin. The potential content of bound water forms in the ground of circumpolar areas of the planet is also estimated.
Litvak, M. L., Mitrofanov, I. G., Kozyrev, A. S., Sanin, A. B., Tret'yakov, V., Boynton, W. V., Shinohara, C., Hamara, D., Saunders, S., & Drake, D. M. (2004). Seasonal carbon dioxide depositions on the martian surface as revealed from neutron measurements by the HEND Instrument onboard the 2001 Mars Odyssey spacecraft. Solar System Research, 38(3), 167-177.
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Abstract: We present the results of eighteen months of observations of the seasonal caps of Mars based on data from the neutron spectroscopy of the surface by the Russian HEND Instrument mounted aboard the NASA 2001 Mars Odyssey spacecraft. A four-dimensional model of the Martian seasonal caps was developed on the basis of these observation data. The model shows how the thickness of the frozen carbon dioxide changes in different surface regions. Using the results of the model, we estimated the total mass of the seasonal caps for the period of maximal accumulation of seasonal depositions and the rates of condensation and sublimation of the seasonal cover.
Mitrofanov, I. G., Litvak, M. L., Kozyrev, A. S., Sanin, A. B., Tret'yakov, V., Grin'kov, V., Boynton, W. V., Shinohara, C., Hamara, D., & Saunders, R. S. (2004). Soil water content on Mars as estimated from neutron measurements by the HEND instrument onboard the 2001 Mars Odyssey spacecraft. Solar System Research, 38(4), 253-257.
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Abstract: We present the results of 20 months of observations of Mars by the Russian HEND instrument onboard the NASA 2001 Mars Odyssey spacecraft. We show that there are two extended subpolar regions with a soil water content of several tens of percent in the northern and southern hemispheres of Mars. The southern subpolar region is well described by a two-layer model, according to which a soil with a water content of up to 55% by mass lies under a relatively dry soil with a water mass fraction of 2% and a thickness of 15-20 g/cm 2. The distribution of water in Martian regolith northern subpolar region is in good agreement with the homogeneous model and does not require invoking the more complex two-layer soil model. The water-ice content in the subsurface layer of the northern subpolar region reaches 53 % by mass. We show that there are two regions with a relatively high water content near the Martian equator. These are Arabia Terra and the Medusae Fossae formation region southwest of Olympus Mons. In these regions, a lower layer with 9-10% of water by mass may underlie the upper layer of relatively dry material ∼30 g/cm 2 in thickness. The "moistest" spot near the equator is at about 30° E and 10° N. Its lower-layer soil may contain more than 16% of water by mass.
Patzer, A., Hill, D. H., & Boynton, W. V. (2004). Evolution and classification of acapulcoites and lodranites from a chemical point of view. Meteoritics and Planetary Science, 39(1), 61-85.
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Abstract: We examined 15 bulk samples of the acapulcoite-lodranite clan for their major, minor, and trace element concentrations using INAA techniques. Among the analyzed meteorites are 2 new acapulcoites (Dhofar [Dho] 290, Thiel Mountains [TIL] 99002) as well as an additional acapulcoite that has been described previously only in very brief form (Graves Nunataks [GRA] 98028). The petrographic attributes of these 3 samples are addressed thoroughly. We also include petrographic information on 2 acapulcoites from Africa: Northwest Africa (NWA) 725 and NWA 1058. In general, our study strongly supports the widely accepted idea that acapulcoites and lodranites evolved through partial melting and melt migration of metal/sulfide phases and plagioclase. Furthermore, we concur with previous researchers that the original bimodal classification scheme for acapulcoites and lodranites proves to be too simple. Based on our data set, we introduce an alternative, extended scheme. With respect to their elemental distribution patterns, we distinguish 5 subtypes comprising primitive, typical, transitional, and enriched acapulcoites on one hand and lodranites on the other. The chemical distinction between the primitive, typical, and transitional acapulcoites is rather subtle and gradual. It stands in contrast to the clear modifications observed for the signatures of the enriched acapulcoites and the lodranites. The definition of subcategories basically reflects the concentrations of 2 key elements: K and Se. We note, however, that the assignment of subgroups may not be exclusively inferred from elemental abundances but should also consider additional petrographic information. © Meteoritical Society, 2004.
Patzer, A., Schlüter, J., Schultz, L., Tarkian, M., Hill, D. H., & Boynton, W. V. (2004). New findings for the equilibrated enstatite chondrite Grein 002. Meteoritics and Planetary Science, 39(9), 1555-1575.
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Abstract: We report new petrographic and chemical data for the equilibrated EL chondrite Grein 002, including the occurrence of osbornite, metallic copper, abundant taenite, and abundant diopside. As inferred from low Si concentrations in kamacite, the presence of ferroan alabandite, textural deformation, chemical equilibration of mafic silicates, and a subsolar noble gas component, we concur with Grein 002's previous classification as an EL4-5 chondrite. Furthermore, the existence of pockets consisting of relatively coarse, euhedral enstatite crystals protruding large patches of Fe-Ni alloys suggests to us that this EL4-5 chondrite has been locally melted. We suspect impact induced shock to have triggered the formation of the melt pockets. Mineralogical evidence indicates that the localized melting of metal and adjacent enstatite must have happened relatively late in the meteorite's history. The deformation of chondrules, equilibration of mafic silicates, and generation of normal zoning in Fe, Zn-sulfides took place during thermal alteration before the melting event. Following parent body metamorphism, daubreelite was exsolved from troilite in response to a period of slow cooling at subsolidus temperatures. Exsolution of schreibersite from the coarse metal patches probably occurred during a similar period of slow cooling subsequent to the event that induced the formation of the melt pockets. Overall shock features other than localized melting correspond to stage S2 and were likely established by the final impact that excavated the Grein 002 meteoroid. © Meteoritical Society, 2004.
Prettyman, T. H., Feldman, W. C., Mellon, M. T., McKinney, G. W., Boynton, W. V., Karuantillake, S., Lawrence, D. J., Maurice, S., Metzger, A. E., Murphy, J. R., Squyres, S. W., Starr, R. D., & Tokar, R. L. (2004). Composition and structure of the Martian surface at high southern latitudes from neutron spectroscopy. Journal of Geophysical Research E: Planets, 109(5), E05001 1-28.
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Abstract: Neutron spectroscopy data acquired by Mars Odyssey are analyzed to determine the abundance and depth of near-surface water ice as a function of latitude in the southern hemisphere as well as the inventory Of CO2 in the south polar residual cap. The surface is modeled as a semi-infinite, water-rich permafrost layer covered by desiccated material, which is consistent with theoretical models of ground ice stability. Latitude-dependent parameters, water abundance and depth, are determined from zonally averaged neutron counting data. Spatial mixing of the output of neutrons from regions within the footprint of the spectrometer is modeled, and asymmetrical features such as the residual cap are included in the analysis. Absorption of thermal neutrons by major elements other than hydrogen is found to have a significant influence on the determination of water abundance. Poleward of -60°, the water-rich layer contains 60% ± 10% water by weight (70% to 85% by volume) and is covered by less than 15 g/cm2 ± 5 g/cm2 of dry material. The volume fraction of water is generally higher than can be accommodated in the pore space of surface soils, which implies that water vapor diffusion processes alone cannot explain the observations. Alternatives for the formation of the water-rich layer are discussed. Results of our analysis of the residual-cap CO2 inventory support conclusions that the atmosphere is not buffered by a larger reservoir of surface CO2 at the poles and that Mars' total CO2 inventory is well represented by the present atmospheric mass. Copyright 2004 by the American Geophysical Union.
Saunders, R. S., Arvidson, R. E., Badhwar, G. D., Boynton, W. V., Christensen, P. R., Cucinotta, F. A., Feldman, W. C., Gibbs, R. G., Kloss Jr., C., Landano, M. R., Mase, R. A., Mcsmith, G. W., Meyer, M. A., Mitrofanov, I. G., Pace, G. D., Plaut, J. J., Sidney, W. P., Spencer, D. A., Thompson, T. W., & Zeitlin, C. J. (2004). 2001 Mars Odyssey mission summary. Space Science Reviews, 110(1-2), 1-36.
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Abstract: The 2001 Mars Odyssey spacecraft, now in orbit at Mars, will observe the Martian surface at infrared and visible wavelengths to determine surface mineralogy and morphology, acquire global gamma ray and neutron observations for a full Martian year, and study the Mars radiation environment from orbit. The science objectives of this mission are to: (1) globally map the elemental composition of the surface, (2) determine the abundance of hydrogen in the shallow subsurface, (3) acquire high spatial and spectral resolution images of the surface mineralogy, (4) provide information on the morphology of the surface, and (5) characterize the Martian near-space radiation environment as related to radiation-induced risk to human explorers. To accomplish these objectives, the 2001 Mars Odyssey science payload includes a Gamma Ray Spectrometer (GRS), a multi-spectral Thermal Emission Imaging System (THEMIS), and a radiation detector, the Martian Radiation Environment Experiment (MARIE). THEMIS and MARIE are mounted on the spacecraft with THEMIS pointed at nadir. GRS is a suite of three instruments: a Gamma Subsystem (GSS), a Neutron Spectrometer (NS) and a High-Energy Neutron Detector (HEND). The HEND and NS instruments are mounted on the spacecraft body while the GSS is on a 6-m boom. Some science data were collected during the cruise and aerobraking phases of the mission before the prime mission started. THEMIS acquired infrared and visible images of the Earth-Moon system and of the southern hemisphere of Mars. MARIE monitored the radiation environment during cruise. The GRS collected calibration data during cruise and aerobraking. Early GRS observations in Mars orbit indicated a hydrogen-rich layer in the upper meter of the subsurface in the Southern Hemisphere. Also, atmospheric densities, scale heights, temperatures, and pressures were observed by spacecraft accelerometers during aerobraking as the spacecraft skimmed the upper portions of the Martian atmosphere. This provided the first in-situ evidence of winter polar warming in the Mars upper atmosphere. The prime mission for 2001 Mars Odyssey began in February 2002 and will continue until August 2004. During this prime mission, the 2001 Mars Odyssey spacecraft will also provide radio relays for the National Aeronautics and Space Administration (NASA) and European landers in early 2004. Science data from 2001 Mars Odyssey instruments will be provided to the science community via NASA's Planetary Data System (PDS). The first PDS release of Odyssey data was in October 2002; subsequent releases occur every 3 months.
Sprague, A. L., Boynton, W. V., Kerry, K. E., Janes, D. M., Hunten, D. M., Kim, K. J., Reedy, R. C., & Metzger, A. E. (2004). Mars' south polar Ar enhancement: A tracer for south polar seasonal meridional mixing. Science, 306(5700), 1364-1367.
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PMID: 15472041;Abstract: The gamma ray spectrometer on the Mars Odyssey spacecraft measured an enhancement of atmospheric argon over southern high latitudes during autumn followed by dissipation during winter and spring. Argon does not freeze at temperatures normal for southern winter (∼145 kelvin) and is left in the atmosphere, enriched relative to carbon dioxide (CO2), as the southern seasonal cap of CO2 frost accumulates. Calculations of seasonal transport of argon into and out of southern high latitudes point to meridional (north-south) mixing throughout southern winter and spring.
Basilevsky, A. T., Litvak, M. L., Mitrofanov, I. G., Boynton, W. V., Saunders, R. S., & Head, J. W. (2003). Search for Traces of Chemically Bound Water in the Martian Surface Layer Based on Hend Measurements Onboard the 2001 Mars Odyssey Spacecraft. Solar System Research, 37(5), 387-396.
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Abstract: Analysis of the distribution of the epithermal and fast neutron fluxes from the Martian surface within the ±60° latitude zone measured by the High-Energy Neutron Detector (HEND) from mid-February through mid-June 2002 has revealed regional neutron-flux variations outside the zones of climatic effects, which appear to be attributable to the presence of chemically bound water. With the exception of the epithermal neutron fluxes in Arabia and southwest of Olympus Mons (Medusae Fossae), these variations show no correlation with the geologic structure of the terrain at the level of global geologic maps. The lack of such a correlation probably implies that to the formation depth of the epithermal neutron flux (1-2 m), let alone the fast neutron flux (20-30 cm), much of Mars is covered by a surface material that bears little relation in composition to local bedrocks. Clearly, this is an aeolian cover whose fine-grain component was mixed by dust storms in the geologic time on the scale of large regions. The decrease in the flux of epithermal neutrons in Arabia and southwest of Olympus Mons (Medusae Fossae) appears to be attributable to an enhanced concentration of materials containing chemically bound water (clay minerals, palagonite, hydroxides, and hydrosalts) in the surface layers of these regions.
Feldman, W. C., Prettyman, T. H., Boynton, W. V., Murphy, J. R., Squyres, S., Karunatillake, S., Maurice, S., Tokar, R. L., McKinney, G. W., Hamara, D. K., Kelly, N., & Kerry, K. (2003). CO₂ frost cap thickness on Mars during northern winter and spring. Journal of Geophysical Research E: Planets, 108(9), 7-1.
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Abstract: The thickness of seasonal CO2 frost that covers the north pole of Mars during the winter and spring seasons is studied using gamma ray and neutron data measured using the gamma ray spectrometer suite of instruments aboard Mars Odyssey. The resultant seasonal variation of CO2 ice/frost thickness for latitudes greater than +85° is in close agreement (within 9% at maximum) with those predicted using all three major Mars general circulation models presently in use. These observed CO2 ice results are significantly different from those inferred from the Mars Obiter Laser Altimeter experiment aboard Mars Global Surveyor (MGS). A possible explanation is that the density of the CO2 ice/ frost cap is considerably lower than that inferred from observed variations of the MGS orbit. Other significant results are that the thermal neutron counting rates provide evidence for variations in the abundance of noncondensable components of the polar atmosphere of Mars and that the basement terrain below the seasonal cover of CO2 frost within about 10° of the pole is nearly 100% water ice.
Hill, D. L., & Boynton, W. V. (2003). Chemistry of the Calcalong Creek lunar meteorite and its relationship to lunar terranes. Meteoritics and Planetary Science, 38(4), 595-626.
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Abstract: The Calcalong Creek lunar meteorite is a polymict breccia that contains clasts of both highlands and mare affinity. Reported here is a compilation of major, minor, and trace element data for bulk, clast, and matrix samples determined by instrumental neutron activation analysis (INAA). Petrographic information and results of electron microprobe analyses are included. The relationship of Calcalong Creek to lunar terranes, especially the Procellarum KREEP Terrane and Feldspathic Highlands Terrane, is established by the abundance of thorium, incompatible elements and their KREEP-like Cl chondrite normalized pattern, FeO, and TiO2. The highlands component is associated with Apollo 15 KREEP basalt but represents a variant of the KREEP-derived material widely found on the moon. Sources of Calcalong Creek's mare basalt components may be related to low-titanium (LT) and very low-titanium (VLT) basalts seen in other lunar meteorites but do not sample the same source. The content of some components of Calcalong Creek are found to display similarities to the composition of the South Pole-Aitken Terrane. What appear to be VLT relationships could represent new high aluminum, low titanium basalt types.
Litvak, M. L., Mitrofanov, I. G., Kozyrev, A. S., Sanin, A. B., Tret'yakov, V., Boynton, W. V., Shinohara, C., Hamara, D., Saunders, S., Drake, D. M., Zuber, M. T., & Smith, D. E. (2003). Seasonal Neutron-Flux Variations in the Polar Caps of Mars as Revealed by the Russian HEND Instrument Onboard the NASA 2001 Mars Odyssey Spacecraft. Solar System Research, 37(5), 378-386.
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Abstract: We analyze the flux of epithermal neutrons from the Martian surface recorded by the Russian High-Energy Neutron Detector (HEND) from February 19 through December 19, 2002. The HEND was installed onboard the NASA 2001 Mars Odyssey spacecraft and is designed to measure neutron fluxes with energies above 1 eV. Over the period of observations, statistically significant variations in the flux of epithermal (10-100 keV) neutrons were found in the northern and southern polar caps. The largest neutron-flux variations were found at subpolar latitudes, where the relative difference between the summer and winter values can reach severalfold. This correlation becomes weaker with increasing distance from the poles. Thus, the relative change in the neutron flux near the 60° parallel is slightly more than 10%. We assume that the detected variations result from the global circulation of atmospheric carbon dioxide in subpolar Martian regions. To additionally test this assumption, we compared the HEND neutron measurements onboard 2001 Mars Odyssey and the seasonal variations in the CO2-layer thickness as observed by the Mars Orbital Laser Altimeter (MOLA) onboard Mars Global Surveyor (MGS).
Lorenz, R. D., Boynton, W. V., & Turner, C. (2003). Demonstration of comet sample collection by penetrator. European Space Agency, (Special Publication) ESA SP, 387-393.
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Abstract: We describe laboratory tests to investigate and demonstrate the acquisition and encapsulation of a subsurface sample from a comet analogue using a coring penetrator. The penetrator imbeds itself in the target, coring out a sample during the impact itself. Mechanisms seal the sample in a canister and the canister is spring-ejected from the rear of the penetrator where it can be retrieved in free-flight by a mother spacecraft, which thus need not perform a landing. We describe the penetrator vehicle, sample preparation and testing technique using the large airgun at the University of Arizona, and the performance results which indicate the technique is an attractive option for comet nucleus sample return.
Mitrofanov, I. G., Litvak, M. L., Kozyrev, A. S., Sanin, A. B., Tret'yakov, V., Boynton, W. V., Shinohara, C., Hamara, D., Saunders, S., & Drake, D. M. (2003). Search for Water in Martian Soil Using Global Neutron Mapping by the Russian HEND Instrument Onboard the US 2001 Mars Odyssey Spacecraft. Solar System Research, 37(5), 366-377.
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Abstract: We present the first results of the global neutron mapping of Mars by the Russian High-Energy Neutron Detector (HEND) onboard the US 2001 Mars Odyssey spacecraft. Global neutron maps of Mars in various spectral ranges allow the content of water ice and adsorbed and bound water in a near-surface layer of the planet 1 to 2 m in thickness to be estimated. Huge regions of permafrost with a high (several tens of percent by weight) content of water ice are shown to be present in the north and the south of Mars. The continuous observations of Mars for 12 months, from February 18, 2002, through February 8, 2003, are indicative of significant seasonal variations on Mars where the transition from northern winter to northern summer occurred.
Mitrofanov, I. G., Zuber, M. T., Litvak, M. L., Boynton, W. V., Smith, D. E., Drake, D., Hamara, D., Kozyrev, A. S., Sanin, A. B., Shinohara, C., Saunders, R. S., & Tretyakov, V. (2003). CO₂ snow depth and subsurface water-ice abundance in the northern hemisphere of Mars. Science, 300(5628), 2081-2084.
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PMID: 12829779;Abstract: Observations of seasonal variations of neutron flux from the high-energy neutron detector (HEND) on Mars Odyssey combined with direct measurements of the thickness of condensed carbon dioxide by the Mars Orbiter Laser Altimeter (MOLA) on Mars Global Surveyor show a latitudinal dependence of northern winter deposition of carbon dioxide. The observations are also consistent with a shallow substrate consisting of a layer with water ice overlain by a layer of drier soil. The lower ice-rich layer contains between 50 and 75 weight % water, indicating that the shallow subsurface at northern polar latitudes on Mars is even more water rich than that in the south.
Patzer, A., Hill, D. H., & Boynton, W. V. (2003). New eucrite Dar al Gani 872: Petrography, chemical composition, and evolution. Meteoritics and Planetary Science, 38(5), 783-794.
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Abstract: Dar al Gani 872 (DaG 872) is a new meteorite from Libya that we classified by means of Instrumental Neutron Activation Analysis (INAA), electron microprobe, and optical microscopy. According to our results, DaG 872 is a Mg-rich main group eucrite, i.e., a monomict noncumulate basaltic eucrite displaying a predominant coarse-grained relict subophitic and a fine-grained granulitic texture. The meteorite also shows pockets of late-stage mesostasis and is penetrated by several calcite veins due to terrestrial weathering. Finally, it exhibits shock phenomena of stage 1-2 including heavily fractured mineral components, undulose extinction of plagioclase, kinked lamellae, and mosaicism in pyroxenes corresponding to peak pressures of ∼20 GPa. In view of petrographic criteria as well as compositional and exsolution characteristics of its pyroxenes, the sample represents a metamorphic type 5 eucrite. Assuming the metamorphic type to be a function of burial depth on the parent body and taking into account the relatively high shock stage, the excavation of DaG 872 was likely induced by a major impact event. Prior to this point, DaG 872 apparently underwent a 4-stage geological evolution that is reflected by intricate textural and mineralogical features.
Price, P. A., Kulkarni, S. R., Berger, E., Fox, D. W., Bloom, J. S., Djorgovski, S. G., Frail, D. A., Galama, T. J., Harrison, F. A., McCarthy, P., Reichart, D. E., Sari, R., Yost, S. A., Jerjen, H., Flint, K., Phillips, A., Warren, B. E., Axelrod, T. S., Chevalier, R. A., , Holtzman, J., et al. (2003). Discovery of GRB 020405 and its late red bump. Astrophysical Journal Letters, 589(2 I), 838-843.
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Abstract: We present the discovery of GRB 020405 made with the Interplanetary Network (IPN). With a duration of 60 s, the burst appears to be a typical long-duration event. We observed the 75 arcmin2 IPN error region with the Mount Stromlo Observatory's 50 inch robotic telescope and discovered a transient source that subsequently decayed and was also associated with a variable radio source. We identify this source as the afterglow of GRB 020405. Subsequent observations by other groups found varying polarized flux and established a redshift of 0.690 to the host galaxy. Motivated by the low redshift, we triggered observations with WFPC2 on board the Hubble Space Telescope (HST). Modeling the early ground-based data with a jet model, we find a clear red excess over the decaying optical light curves that is present between day 10 and day 141 (the last HST epoch). This bump has the spectral and temporal features expected of an underlying supernova (SN). In particular, the red color of the putative SN is similar to that of the SN associated with GRB 011121 at late time. Restricting the sample of GRBs to those with z < 0.7, a total of five bursts, red bumps at late times are found in GRB 970228, GRB 011121, and GRB 020405. It is possible that the simplest idea, namely, that all long-duration γ-ray bursts have underlying SNe with a modest dispersion in their properties (especially peak luminosity), is sufficient to explain the nondetections.
Boynton, W. V., Feldman, W. C., Squyres, S. W., Prettyman, T. H., Brückner, J., Evans, L. G., Reedy, R. C., Starr, R., Arnold, J. R., Drake, D. M., Englert, P. A., Metzger, A. E., Mitrofanov, I., Trombka, J. I., D'Uston, C., Wänke, H., Gasnault, O., Hamara, D. K., Janes, D. M., , Marcialis, R. L., et al. (2002). Distribution of hydrogen in the near surface of Mars: Evidence for subsurface ice deposits. Science, 297(5578), 81-85.
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PMID: 12040090;Abstract: Using the Gamma-Ray Spectrometer on the Mars Odyssey, we have identified two regions near the poles that are enriched in hydrogen. The data indicate the presence of a subsurface layer enriched in hydrogen overlain by a hydrogen-poor layer. The thickness of the upper layer decreases with decreasing distance to the pole, ranging from a column density of about 150 grams per square centimeter at -42° latitude to about 40 grams per square centimeter at -77°. The hydrogen-rich regions correlate with regions of predicted ice stability. We suggest that the host of the hydrogen in the subsurface layer is ice, which constitutes 35 ± 15% of the layer by weight.
Feldman, W. C., Boynton, W. V., Tokar, R. L., Prettyman, T. H., Gasnault, O., Squyres, S. W., Elphic, R. C., Lawrence, D. J., Lawson, S. L., Maurice, S., McKinney, G. W., Moore, K. R., & Reedy, R. C. (2002). Global distribution of neutrons from Mars: Results from Mars Odyssey. Science, 297(5578), 75-78.
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PMID: 12040088;Abstract: Global distributions of thermal, epithermal, and fast neutron fluxes have been mapped during late southern summer/northern winter using the Mars Odyssey Neutron Spectrometer. These fluxes are selectively sensitive to the vertical and lateral spatial distributions of H and CO2 in the uppermost meter of the martian surface. Poleward of ±60° latitude is terrain rich in hydrogen, probably H2O ice buried beneath tens of centimeter-thick hydrogen-poor soil. The central portion of the north polar cap is covered by a thick CO2 layer, as is the residual south polar cap. Portions of the low to middle latitudes indicate subsurface deposits of chemically and/or physically bound H2O and/or OH.
Feldman, W. C., Prettyman, T. H., Tokar, R. L., Boynton, W. V., Byrd, R. C., Fuller, K. R., Gasnault, O., Longmire, J. L., Olsher, R. H., Storms, S. A., & Thornton, G. W. (2002). Fast neutron flux spectrum aboard Mars Odyssey during cruise. Journal of Geophysical Research A: Space Physics, 107(A6).
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Abstract: [1] The energy spectrum of fast neutrons generated by interactions between galactic cosmic rays and the Mars Odyssey spacecraft during quiet interplanetary conditions is determined. It is given by Φn(En) = (0.071 ± 0.0044) En-(0.28±0.055) cm -2 s-1 MeV-1 for energies between 0.7 and 6 MeV. The estimated ratio of this component of spacecraft neutron background to the Martian leakage flux in Mars orbit is expected to amount to between 0.30 and 0.34. This fraction is sufficiently small so that the total background in orbit about Mars is expected to be dominated by Martian leakage neutrons reprocessed by the spacecraft. Nevertheless, the measured asymmetry properties of the Odyssey Neutron Spectrometer response function should allow separation of foreground and background neutron fluxes when in Mars orbit. The fast neutron flux between 0.7 and 6 MeV should only contribute 0.40 Roentgen Equivalent Man (rem) per year to the total radiation dose aboard a Mars Odyssey class spacecraft at solar maximum. Copyright 2002 by the American Geophysical Union.
Mitrofanov, I., Anfimov, D., Kozyrev, A., Litvak, M., Sanin, A., Tret'yakov, V., Krylov, A., Shvetsov, V., Boynton, W., Shinohara, C., Hamara, D., & Saunders, R. S. (2002). Maps of subsurface hydrogen from the High Energy Neutron Detector, Mars Odyssey. Science, 297(5578), 78-81.
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PMID: 12040089;Abstract: After 55 days of mapping by the High Energy Neutron Detector onboard Mars Odyssey, we found deficits of high-energy neutrons in the southern highlands and northern lowlands of Mars. These deficits indicate that hydrogen is concentrated in the subsurface. Modeling suggests that water ice-rich layers that are tens of centimeters in thickness provide one possible fit to the data.
Patzer, A., Hill, D. H., Boynton, W. V., Franke, L., Schultz, L., Jull, A. T., McHargue, L. R., & Franchi, I. A. (2002). Itqiy: A study of noble gases and oxygen isotopes including its terrestrial age and a comparison with Zakłodzie. Meteoritics and Planetary Science, 37(6), 823-833.
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Abstract: We report noble gas, oxygen isotope, 14C and 10Be data of Itqiy as well as noble gas, 14C and 10Be results for Zakłodzie. Both samples have been recently classified as anomalous enstatite meteorites and have been compared in terms of their mineralogy and chemical composition. The composition of enstatite and kamacite and the occurrence of specific sulfide phases in Itqiy indicate it formed under similar reducing conditions to those postulated for enstatite chondrites. The new results now seem to point at a direct spatial link. The noble gas record of Itqiy exhibits the presence of a trapped subsolar component, which is diagnostic for petrologic types 4-6 among enstatite chondrites. The concentration of radiogenic 4He is very low in Itqiy and indicates a recent thermal event. Its 21Ne cosmic-ray exposure age is 30.1 ± 3.0 Ma and matches the most common age range of enstatite chondrites (mostly EL6 chondrites) but not that of Zakłodzie. Itqiy's isotopic composition of oxygen is in good agreement with that observed in Zakłodzie as well as those found in enstatite meteorites suggesting an origin from a common oxygen pool. The noble gas results, on the other hand, give reason to believe that the origin and evolution of Itqiy and Zakłodzie are not directly connected. Itqiy's terrestrial age of 5800 ± 500 years sheds crucial light on the uncertain circumstances of its recovery and proves that Itqiy is not a modern fall, whereas the 14C results from Zaklodzie suggest it hit Earth only recently.
Tokar, R. L., Feldman, W. C., Prettyman, T. H., Moore, K. R., Lawrence, D. J., Elphic, R. C., Kreslavsky, M. A., Head, I., Mustard, J. F., & Boynton, W. V. (2002). Ice concentration and distribution near the south pole of Mars: Synthesis of odyssey and global surveyor analyses. Geophysical Research Letters, 29(19), 10-1.
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Abstract: Mars Odyssey Gamma-Ray Spectrometer (GRS) neutron spectrometer data are analyzed to determine the concentration and boundary of buried water ice near the south pole. The measurements are consistent with a circumpolar layer of average ice concentration from 35 to 100% by weight and superposed dust with thickness density product 30 to 40 g/cm2. The region of buried water ice extends from near the south pole to latitudes 48S to 58S. The equatorward boundary of the ice-rich region compares favorably with the boundary of an ice-rich dust mantle inferred from Mars Orbiter Laser Altimeter data and the locations of dissected terrain inferred from Mars Orbiter Camera images. The ice-rich mantle is identified as the source of enhanced hydrogen sensed by the neutron spectrometer.
Boynton, W. V., Bailey, S. H., Hamara, D. K., Williams, M. S., Bode, R. C., Fitzgibbon, M. R., WenJeng, K. o., Ward, M. G., Sridhar, K. R., Blanchard, J. A., Lorenz, R. D., May, R. D., Paige, D. A., Pathare, A. V., Kring, D. A., Leshin, L. A., Ming, D. W., Zent, A. P., Golden, D. C., , Kerry, K. E., et al. (2001). Thermal and Evolved Gas Analyzer: Part of the Mars Volatile and Climate Surveyor integrated payload. Journal of Geophysical Research E: Planets, 106(E8), 17683-17698.
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Abstract: The Thermal and Evolved Gas Analyzer (TEGA) on the Mars Polar Lander spacecraft is composed of two separate components which are closely coupled: a Differential Scanning Calorimeter (DSC) and an Evolved Gas Analyzer (EGA). TEGA has the capability of performing differential scanning calorimetry on eight small (0.038 mL) soil samples selected in the vicinity of the lander. The samples will be heated in ovens to temperatures up to 950°C, and the volatile compounds water and carbon dioxide, which are released during the heating, will be analyzed in the EGA. The power required by the sample oven is continuously monitored during the heating and compared to that required to heat simultaneously a similar, but empty, oven. The power difference is the output of the DSC. Both endothermic and exothermic phase transitions can be detected, and the data can be used in the identification of the phases present. By correlating the gas release with the calorimetry, the abundance of the volatile compounds associated with the different phases can be determined. The EGA may also be able to detect the release of oxygen associated with any superoxide that may be on the surface of the soil grains. The instrument can detect the melting of ice in the DSC down to abundances on the order of 0.2% of the sample, and it can detect the decomposition of calcite, CaCO3, down to abundances of 0.5%. Using the EGA, TEGA can detect small amounts of water, down to 8 ppm in the sample, and it can detect the associated release of CO2 down to the equivalent abundances of 0.03%. The EGA also has the ability to determine the 13C/12C ratio in the evolved CO2, but it is not clear if the accuracy of this ratio will be sufficient to address the scientific issues. Copyright 2001 by the American Geophysical Union.
Evans, L. G., Starr, R. D., Brückner, J., Reedy, R. C., Boynton, W. V., Trombka, J. I., Goldsten, J. O., Masarik, J., Nittler, L. R., & McCoy, T. J. (2001). Elemental compositional from gamma-ray spectroscopy of the NEAR-shoemaker landing site on 433 Eros. Meteoritics and Planetary Science, 36(12), 1639-1660.
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Abstract: Elemental composition and composition ratios derived from gamma-ray measurements collected by the NEAR-Shoemaker spacecraft while on the surface of 433 Eros are reported. Performance of the gamma-ray spectrometer (GRS) during cruise and orbit is reviewed. The best gamma-ray data were collected on the surface of Eros after the spacecraft's controlled descent on 2001 February 12. Methods used in spectral analysis, to convert peak areas to incident photons, and photons to elemental composition are described in some detail. The elemental abundance of K and the Mg/Si, Fe/Si, Si/O and Fe/O abundance ratios were determined. The Mg/Si and Si/O ratios and the K abundance are roughly chondritic, but the Fe/Si and Fe/O ratios are low compared to expected chondritic values. Three possible explanations for the apparent Fe depletion are considered.
May, R. D., Forouhar, S., Crisp, D., Woodward, W. S., Paige, D. A., Pathare, A., & Boynton, W. V. (2001). The MVACS tunable diode laser spectrometers. Journal of Geophysical Research E: Planets, 106(E8), 17673-17682.
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Abstract: Two independent tunable diode laser spectrometers are resident aboard the Mars Polar Lander as part of the Mars Volatiles and Climate Surveyor payload. One spectrometer is located on the meteorological mast for measurements of H2O and CO2 in the free atmosphere, and the other serves as the H2O and CO2 analyzer for the Thermal and Evolved Gas Analyzer. Water vapor is measured using a tunable diode laser operating at 1.37 μm, while CO2 is measured using a second laser operating near 2.05 μm. The 2.05 μm laser also has isotopic analysis capability. In addition to the major CO2 isotopomer (12C16O16O), analyses of 13C16O16O and 12C18O16O in the atmosphere and in the Thermal and Evolved Gas Analyzer are possible under certain conditions. The spectrometers were designed and built at the Jet Propulsion Laboratory and have their heritage in a series of tunable diode laser spectrometers developed for Earth atmospheric studies using high-altitude aircraft and balloon platforms. The 1.37 μm diode laser on the meteorological mast will provide the first in situ measurements of water vapor in the Martian boundary layer, with a detection sensitivity an order of magnitude greater than the water vapor abundances inferred from the remote-sensing observations by the Viking Orbiters. Copyright 2001 by the American Geophysical Union.
McClanahan, T. P., Trombka, J. I., Nittler, L. R., Boynton, W. V., Bruckner, J., Squyres, S. W., Evans, L. G., Bhangoo, J. S., Clark, P. E., Floyd, S. R., McCartney, E., Mikheeva, I., & Starr, R. D. (2001). Spectral analysis and compositing techniques for the Near Earth Asteroid Rendezvous (NEAR Shoemaker), X-ray and Gamma-Ray Spectrometers (XGRS). Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 471(1-2), 179-183.
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Abstract: An X-ray and Gamma-Ray Spectrometer (XGRS) is on board the Near Earth Asteroid Rendezvous (NEAR) spacecraft to determine the elemental composition of the surface of the asteroid 433 Eros. The Eros asteroid is highly oblate and irregular in shape. As a result, analysis methodologies are in many ways a divergence from comparable techniques. Complex temporal, spatial and instrument performance relationships must be accounted for during the analysis process. Field of view and asteroid surface geometry measurements must be modeled and then combined with real measurements of solar, spectral and instrument calibration information to derive scientific results. NEAR is currently orbiting 433 Eros and is in the initial phases of its primary data integration and mapping phases. Initial results have been obtained and bulk chemistry assessments have been obtained through specialized background assessment and data reduction techniques. © 2001 Published by Elsevier Science B.V.
McCoy, T. J., Burbine, T. H., McFadden, L. A., Starr, R. D., Gaffey, M. J., Nittler, L. R., Evans, T. J., Izenberg, N., Lucey, P. G., Trombka, J. I., III, J. B., Clark, B. E., Clark, P. E., Squyres, S. W., Chapman, C. R., Boynton, W. V., & Veverka, J. (2001). The composition of 433 Eros: A mineralogical-chemical synthesis. Meteoritics and Planetary Science, 36(12), 1661-1672.
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Abstract: The near-Earth asteroid rendezvous (NEAR) mission carried x-ray/gamma-ray spectrometers and multi-spectral imager/near-infrared spectrometer instrument packages which gave complementary information on the chemistry and mineralogy, respectively, of the target asteroid 433 Eros. Synthesis of these two data sets provides information not available from either alone, including the abundance of non-mafic silicates, metal and sulfide minerals. We have utilized four techniques to synthesize these data sets. Venn diagrams, which examine overlapping features in two data sets, suggest that the best match for 433 Eros is an ordinary chondrite, altered at the surface of the asteroid, or perhaps a primitive achondrite derived from material mineralogically similar to these chondrites. Normalized element distributions preclude FeO-rich pyroxenes and suggest that the x-ray and gamma-ray data can be reconciled with a common silicate mineralogy by inclusion of varying amounts of metal. Normative mineralogy cannot be applied to these data sets owing to uncertainties in oxygen abundance and lack of any constraints on the abundance of sodium. Matrix inversion for simultaneous solution of mineral abundances yields reasonable results for the x-ray-derived bulk composition, but seems to confirm the inconsistency between mineral compositions and orthopyroxene/clinopyroxene ratios. A unique solution does not seem possible in synthesizing these multiple data sets. Future missions including a lander to fully characterize regolith distribution and sample return would resolve the types of problems faced in synthesizing the NEAR data.
Nittler, L. R., Starr, R. D., Lim, L., McCoy, T. J., Burbine, T. H., Reedy, R. C., Trombka, J., Gorenstein, P., Squyres, S. W., Boynton, W. V., McClanahan, T. P., Bhangoo, J. S., Clark, P. E., Murphy, M. E., & Killen, R. (2001). X-ray fluorescence measurements of the surface elemental composition of asteroid 433 Eros. Meteoritics and Planetary Science, 36(12), 1673-1695.
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Abstract: We report major element ratios determined for the S-class asteroid 433 Eros using remote-sensing x-ray fluorescence spectroscopy with the near-Earth asteroid rendezvous Shoemaker x-ray spectrometer (XRS). Data analysis techniques and systematic errors are described in detail. Data acquired during five solar flares and during two extended "quiet Sun" periods are presented; these results sample a representative portion of the asteroid's surface. Although systematic uncertainties are potentially large, the most internally consistent and plausible interpretation of the data is that Eros has primitive Mg/Si, Al/Si, Ca/Si and Fe/Si ratios, closely similar to H or R chondrites. Global differentiation of the asteroid is ruled out. The S/Si ratio is much lower than that of chondrites, probably reflecting impact-induced volatilization and/or photo- or ion-induced sputtering of sulfur at the surface of the asteroid. An alternative explanation for the low S/Si ratio is that it reflects a limited degree of melting with loss of an FeS-rich partial melt. Size-sorting processes could lead to segregation of Fe-Ni metal from silicates within the regolith of Eros; this could indicate that the Fe/Si ratios determined by the x-ray spectrometer are not representative of the bulk Eros composition.
Patzer, A., Hill, D. H., & Boynton, W. V. (2001). Itqiy: A metal-rich enstatite meteorite with achondritic texture. Meteoritics and Planetary Science, 36(11), 1495-1505.
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Abstract: Itqiy is a unique coarse-grained, metal-rich enstatite meteorite that was found in the Western Sahara and consists of two rocks together weighing 4.72 kg, which are both completely coated with fusion crust. We report results from our electron microprobe and instrumental neutron activation analysis techniques. Itqiy consists of subhedral, equigranular, millimeter-sized enstatite, ∼25 vol% of millimeter-sized kamacite and a few tiny intergrowths of sulfides and kamacite. Relic chondrules are absent. Pyroxene (Fs0.2) is chemically similar to enstatite in EL chondrites, but the metal is closer in composition to that in EH chondrites. Sulfides resemble those in E chondrites but their compositions are distinct from those in both EL and EH chondrites. Itqiy clearly formed under very reducing conditions, but it does not appear to have formed from EH or EL chondrites. Two thermal events can be distinguished. Silicate compositions including rare earth element abundances indicate loss of partial melt and slow cooling. Heterogeneous sulfides indicate a subsequent reheating and quenching event, which may have been due to shock as many enstatite grains show shock stage S3 features.
Solomon, S. C., McNutt Jr., R. L., Gold, R. E., Acuña, M. H., Baker, D. N., Boynton, W. V., Chapman, C. R., Cheng, A. F., Gloeckler, G., W., J., Krimigis, S. M., McClintock, W. E., Murchie, S. L., Peale, S. J., Phillips, R. J., Robinson, M. S., Slavin, J. A., Smith, D. E., Strom, R. G., , Trombka, J. I., et al. (2001). The MESSENGER mission to Mercury: Scientific objectives and implementation. Planetary and Space Science, 49(14-15), 1445-1465.
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Abstract: Mercury holds answers to several critical questions regarding the formation and evolution of the terrestrial planets. These questions include the origin of Mercury's anomalously high ratio of metal to silicate and its implications for planetary accretion processes, the nature of Mercury's geological evolution and interior cooling history, the mechanism of global magnetic field generation, the state of Mercury's core, and the processes controlling volatile species in Mercury's polar deposits, exosphere, and magnetosphere. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission has been designed to fly by and orbit Mercury to address all of these key questions. After launch by a Delta 2925H-9.5, two flybys of Venus, and two flybys of Mercury, orbit insertion is accomplished at the third Mercury encounter. The instrument payload includes a dual imaging system for wide and narrow fields-of-view, monochrome and color imaging, and stereo; X-ray and combined gamma-ray and neutron spectrometers for surface chemical mapping; a magnetometer; a laser altimeter; a combined ultraviolet-visible and visible-near-infrared spectrometer to survey both exospheric species and surface mineralogy; and an energetic particle and plasma spectrometer to sample charged species in the magnetosphere. During the flybys of Mercury, regions unexplored by Mariner 10 will be seen for the first time, and new data will be gathered on Mercury's exosphere, magnetosphere, and surface composition. During the orbital phase of the mission, one Earth year in duration, MESSENGER will complete global mapping and the detailed characterization of the exosphere, magnetosphere, surface, and interior. © 2001 Elsevier Science Ltd. All rights reserved.
Wark, D., & Boynton, W. V. (2001). The formation of rims on calcium-aluminum-rich inclusions: Step I-flsah heating. Meteoritics and Planetary Science, 36(8), 1135-1166.
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Abstract: Wark-Lovering rims of six calcium-aluminum-rich inclusions (CAIs) representing the main CAI types and groups in Allende, Efremovka and Vigarano were microsurgically separated and analysed by neutron activation analysis (NAA). All the rims have similar ∼4x enrichments, relative to the interiors, of highly refractory lithophile and siderophile elements. The NAA results are confirmed by ion microprobe and scanning electron microscope (SEM) analyses of rim perovskites and rim metal grains. Less refractory Eu, Yb, V, Sr, Ca and Ni are less enriched in the rims. The refractory element patterns in the rims parallel the patterns in the outer parts of the CAIs. In particular, the rims on type B1 CAIs have the igneously fractionated rare earth element (REE) pattern of the melilite mantle below the rim and not the REE pattern of the bulk CAI, proving that the refractory elements in the rims were derived from the outer mantle and were not condensates onto the CAIs. The refractory elements were enriched in an Al2O3-rich residue
Starr, R., Clark, P. E., Murphy, M. E., Floyd, S. R., McClanahan, T. P., Nittler, L. R., Trombka, J. I., Evans, L. G., Boynton, W. V., Bailey, S. H., Bhangoo, J., Mikheeva, I., Brückner, J., Squyres, S. W., McCartney, E. M., Goldsten, J. O., & McNutt Jr., R. L. (2000). Instrument Calibrations and Data Analysis Procedures for the NEAR X-Ray Spectrometer. Icarus, 147(2), 498-519.
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Abstract: The X-Ray spectrometer onboard the Near Earth Asteroid Rendezvous spacecraft will measure X-rays from the surface of 433 Eros in the energy region 0.7-10 keV. Detection of characteristic Kα line emissions from Mg, Al, Si, Ca, Ti, and Fe will allow the determination of surface abundances of these geologically important elements. Spatial resolution as fine as 3 km will be possible for those elements where counting statistics are not a limiting factor. These measurements will make it possible to relate Eros to known classes of meteorites and reveal geological processes that occurred on Eros. The calibration measurements and analysis procedures presented here are necessary for the reduction and analysis of the X-ray data to be collected during one year of orbital operations at Eros. © 2000 Academic Press.
Trombka, J. I., Squyres, S. W., Bruckner, J., Boynton, W. V., Reedy, R. C., McCoy, T. J., Gorenstein, P., Evans, L. G., Arnold, J. R., Starr, R. D., Nittler, L. R., Murphy, M. E., Mikheeva, I., R.L., J. M., McClanahan, T. P., McCartney, E., Goldsten, J. O., Gold, R. E., Floyd, S. R., , Clark, P. E., et al. (2000). The elemental composition of asteroid 433 Eros: Results of the NEAR-Shoemaker x-ray spectrometer. Science, 289(5487), 2101-2105.
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Abstract: We report major element composition ratios for regions of the asteroid 433 Eros imaged during two solar flares and quiet sun conditions during the period of May to July 2000. Low aluminum abundances for all regions argue against global differentiation of Eros. Magnesium/silicon, aluminum/silicon, calcium/silicon, and iron/silicon ratios are best interpreted as a relatively primitive, chondritic composition. Marked depletions in sulfur and possible aluminum and calcium depletions, relative to ordinary chondrites, may represent signatures of limited partial melting or impact volatilization.
Evans, L. G., Starr, R., Brückner, J., Boynton, W. V., Bailey, S. H., & Trombka, J. I. (1999). Charged-particle induced radiation damage of a HPGe gamma-ray detector during spaceflight. Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 422(1-3), 586-590.
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Abstract: The Mars Observer spacecraft was launched on September 26, 1992 with a planned arrival at Mars after an 11-month cruise. Among the scientific instruments carried on the spacecraft was a Gamma-Ray Spectrometer (GRS) experiment to measure the composition of Mars. The GRS used a passively cooled high-purity germanium detector for measurements in the 0.2-10 MeV region. The sensor was a closed-end co-axial detector, 5.5 cm diameter by 5.5 cm long, and had an efficiency along its axis of 28% at 1332 keV relative to a standard NaI(Tl) detector. The sensor was surrounded by a thin (0.5 cm) plastic charged-particle shield. This was the first planetary mission to use a cooled Ge detector. It was expected that the long duration in space of three years would cause an increase in the energy resolution of the detector due to radiation damage and could affect the expected science return of the GRS. Shortly before arrival, on August 21, 1993, contact was lost with the spacecraft following the pressurization of the propellent tank for the orbital-insertion rocket motor. During much of the cruise to Mars, the GRS was actively collecting background data. The instrument provided over 1200 h of data collection during periods of both quiescent sun and solar flares. From the charged particle interactions in the shield, the total number of cosmic ray hits on the detector could be determined. The average cosmic ray flux at the MO GRS was about 2.5 cm-2 s-1. The estimated fluence of charged particles during cruise was about 108 particles cm-2 with 31% of these occurring during a single solar proton event of approximately 10 days duration. During cruise, the detector energy resolution determined from a background gamma-ray at 1312 keV degraded from 2.4 keV full-width at half-maximum shortly after launch to 6.4 keV 11 months later. This result agrees well with measurements from ground-based accelerator irradiations (at 1.5 GeV) on a similar size detector. © 1999 Elsevier Science B.V. All rights reserved.
McClanahan, T. P., Mikheeva, I., Trombka, J. I., Floyd, S. R., Boynton, W. V., Bailey, H., Bhangoo, J., Starr, R., Clark, P. E., Evans, L. G., Squyres, S., McCartney, E., Noe, E., McNutt, R., & Bruckner, J. (1999). Data processing for the Near Earth Asteroid Rendezvous (NEAR), X-ray and Gamma-ray Spectrometer (XGRS) ground system. Proceedings of SPIE - The International Society for Optical Engineering, 3768, 74-87.
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Abstract: An X-ray and Gamma-ray spectrometer (XGRS) is onboard the Near Earth Asteroid Rendezvous (NEAR) spacecraft to determine the elemental composition of the surface of the asteroid 433Eros. The Eros asteroid is highly non-spherical in physical shape and the development of data management and analysis methodologies are in several areas a divergence from traditional remotely sensed geographical information systems techniques. Field of view and asteroid surface geometry must be derived virtually and then combined with real measurements of solar, spectral and instrument calibration information to derive meaningful scientific results. Spatial resolution of planned geochemical maps will be improved from the initial conditions of low statistical significance per integration by repeated surface flyovers and regional spectral accumulation. This paper describes the results of a collaborative effort of design and development of the NEAR XGRS instrument ground system undertaken by participants at the Goddard Space Flight Center, University of Arizona, Cornell University, Applied Physics Laboratory, and Max Plank institute.
Starr, R., Clark, P. E., Evans, L. G., Floyd, S. R., McClanahan, T. P., Trombka, J. I., Boynton, W. V., Bailey, S., Brückner, J., Squyres, S. W., Goldsten, J. O., & McNutt Jr., R. L. (1999). Cruise measurements taken with the near XGRS. Advances in Space Research, 24(9), 1159-1162.
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Abstract: The X-ray/Gamma-ray Spectrometer on the Near Earth Asteroid Rendezvous spacecraft will remotely detect characteristic x-ray and gamma-ray emissions from the surface of 433 Eros to develop global maps of the elemental composition of the asteroid surface. Solar excited x-ray fluorescence in the 1 to 10 keV range will be used to measure the surface abundances of Mg, Al, Si, Ca, Ti, and Fe with spatial resolutions down to 2 km. Gamma-ray emissions in the 0.1 to 10 MeV range will be used to measure cosmic-ray excited emissions from such elements as O, Si, Fe, and H as well as naturally radioactive elements K, Th, and U to surface depths on the order of 10 cm. In-flight calibrations are essential to the understanding and analysis of data collected at Eros. © 1999 COSPAR. Published by Elsevier Science Ltd.
Trombka, J. I., Boynton, W. V., Brückner, J., Squyres, S., Clark, P. E., Starr, R., Evans, L. G., Floyd, S. R., McClanahan, T. P., Goldsten, J., Mcnutt, R., & Schweitzer, J. S. (1999). Remote planetary geochemical exploration with the NEAR X-ray/gamma-ray spectrometer. Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 422(1-3), 572-576.
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Abstract: The X-ray/gamma-ray spectrometer (XGRS) instrument onboard the Near Earth Asteroid Rendezvous (NEAR) spacecraft will map asteroid 433 Eros in the 0.2 keV to 10 MeV energy region. Measurements of the discrete line X-ray and gamma-ray emissions in this energy domain can be used to obtain both qualitative and quantitative elemental composition maps of the asteroid surface. The NEAR X-ray/gamma-ray spectrometer (XGRS) was turned on for the first time during the week of 7 April 1996. Rendezvous with Eros 433 is expected during December 1998. Observations of solar X-ray spectra during both quiescent and active periods have been made. A gamma-ray transient detection system has been implemented and about three gamma-ray transient events a week have been observed which are associated with either gamma-ray bursts or solar flares. © 1999 Elsevier Science B.V. All rights reserved.
Boynton, W. V., D'Uston, L., Young, D. T., Lunine, J. I., Waite, J. H., Bailey, S. H., Berthelier, J. J., Bertaux, J. L., Borrel, V., Burke, M. F., Cohen, B. A., McComas, D. H., Nordholt, J. E., Evans, L. G., & Trombka, J. I. (1997). The determination of ice composition with instruments on cometary landers. Acta Astronautica, 40(9), 663-674.
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PMID: 11540784;Abstract: The determination of the composition of materials that make up comets is essential in trying to understand the origin of these primitive objects. The ices especially could be made in several different astrophysical settings including the solar nebula, protosatellite nebulae of the giant planets, and giant molecular clouds that predate the formation of the solar system. Each of these environments makes different ices with different composition. In order to understand the origin of comets, one needs to determine the composition of each of the ice phases. For example, it is of interest to know that comets contain carbon monoxide, CO, but it is much more important to know how much of it is a pure solid phase, is trapped in clathrate hydrates, or is adsorbed on amorphous water ice. In addition, knowledge of the isotopic composition of the constituents will help determine the process that formed the compounds. Finally, it is important to understand the bulk elemental composition of the nucleus. When these data are compared with solar abundances, they put strong constraints on the macro-scale processes that formed the comet. A differential scanning calorimeter (DSC) and an evolved-gas analyzer (EGA) will make the necessary association between molecular constituents and their host phases. This combination of instruments takes a small (tens of mg) sample of the comet and slowly heats it in a sealed oven. As the temperature is raised, the DSC precisely measures the heat required, and delivers the gases to the EGA. Changes in the heat required to raise the temperature at a controlled rate are used to identify phase transitions, e.g., crystallization of amorphous ice or melting of hexagonal ice, and the EGA correlates the gases released with the phase transition. The EGA consists of two mass spectrometers run in tandem. The first mass spectrometer is a magnetic-sector ion-momentum analyzer (MAG), and the second is an electrostatic time-of-flight analyzer (TOF). The TOF acts as a detector for the MAG and serves to resolve ambiguities between fragments of similar mass such as CO and N2. Because most of the compounds of interest for the volatile ices are simple, a gas chromatograph is not needed and thus more integration time is available to determine isotopic ratios. A gamma-ray spectrometer (GRS) will determine the elemental abundances of the bulk cometary material by determining the flux of gamma rays produced from the interaction of the cometary material with cosmic-ray produced neutrons. Because the gamma rays can penetrate a distance of several tens of centimeters, a large volume of material is analyzed. The measured composition is, therefore, much more likely to be representative of the bulk comet than a very small sample that might have lost some of its volatiles. Making these measurements on a lander offers substantial advantages over trying to address similar objectives from an orbiter. For example, an orbiter instrument can determine the presence and isotopic composition of CO in the cometary coma, but only a lander can determine the phase(s) in which the CO is located and separately determine the isotopic composition of each reservoir of CO. The bulk composition of the nucleus might be constrained from separate orbiter analyses of dust and gas in the coma, but the result will be very model dependent, as the ratio of gas to dust in the comet will vary and will not necessarily be equal to the bulk value. © 1997 Published by Elsevier Science Ltd.
Boynton, W. V., Evans, L. G., Starr, R., Brueckner, J., Bailey, S. H., & Trombka, J. I. (1997). Induced background in the Mars Observer Gamma-Ray Spectrometer. Conference on the High Energy Radiation Background in Space, Proceedings, 30-33.
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Abstract: The Mars Observer Gamma-Ray Spectrometer has provided data on background lines due to natural and cosmic-ray induced radioactivity during the mission's 11-month cruise. These data will help in determining, for future missions, the sensitivity for detection of gamma-ray lines of interest that are at or near the energy of measured background lines.
Evans, L. G., Trombka, J. I., Starr, R., Boynton, W. V., & Bailey, S. H. (1997). Continuum background in space-borne gamma-ray detectors. Conference on the High Energy Radiation Background in Space, Proceedings, 101-103.
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Abstract: Instrumental backgrounds present a basic limitation to the sensitivity for any gamma-ray detector. This background consists of both discrete lines and a continuum. The discrete background lines are especially important if they occur at the same energies as lines of interest needed for the meeting the science objectives of the mission. The continuum background imposes a limit on the signal to noise ratio that can be achieved. Measurements of the gamma-ray continuum background made during the cruise portion of a number of planetary missions are compared. All of these missions used shields to reduce the continuum background. Measurements made during spaceflight can be used to test the effectiveness of different shield designs.
Gleason, J. D., Kring, D. A., Hill, D. H., & Boynton, W. V. (1997). Petrography and bulk chemistry of Martian lherzolite LEW88516. Geochimica et Cosmochimica Acta, 61(18), 4007-4014.
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Abstract: The meteorite Lewis Cliffs 88516 is a gabbroic lherzolite with geochemical and petrologic characteristics typical of the shergottites, a distinct subgroup of basaltic achondrites belonging to the SNC (Martian) meteorite clan. We report new INAA and microprobe data for LEW88516, noting small but significant differences between our results and those previously published for this meteorite. These discrepancies are mainly attributed to heterogeneities in the bulk rock powder which was distributed to several laboratories for geochemical studies. Other discrepancies are attributed to interlaboratory bias. We emphasize that even minor variations between datasets may have the potential to significantly affect geochemical models for Martian basalts. Small differences in bulk trace element chemistry between LEW88516 and Martian lherzolite ALH77005 may indicate that they crystallized from different magmas. Copyright © 1997 Elsevier Science Ltd.
Gleason, J. D., Kring, D. A., Hill, D. H., & Boynton, W. V. (1997). Petrography and bulk chemistry of Martian orthopyroxenite ALH84001: Implications for the origin of secondary carbonates. Geochimica et Cosmochimica Acta, 61(16), 3503-3512.
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PMID: 11540477;Abstract: New petrologic and bulk geochemical data for the SNC-related (Martian) meteorite ALH84001 suggest a relatively simple igneous history overprinted by complex shock and hydrothermal processes. ALH84001 is an igneous orthopyroxene cumulate containing penetrative shock deformation textures and a few percent secondary extraterrestrial carbonates. Rare earth element (REE) patterns for several splits of the meteorite reveal substantial heterogeneity in REE abundances and significant fractionation of the REEs between crushed and uncrushed domains within the meteorite. Complex zoning in carbonates indicates nonequilibrium processes were involved in their formation, suggesting that CO2-rich fluids of variable composition infiltrated the rock while on Mars. We interpret petrographic textures to be consistent with an inorganic origin for the carbonate involving dissolution-replacement reactions between CO2-charged fluids and feldspathic glass in the meteorite. Carbonate formation clearly postdated processes that last redistributed the REE in the meteorite. Copyright © 1997 Elsevier Science Ltd.
Laros, J. G., Boynton, W. V., Hurley, K. C., Kouveliotou, C., McCollough, M. L., Fishman, G. J., Meegan, C. A., Palmer, D. M., Cline, T. L., Starr, R. D., Trombka, J. I., Boer, M., Niel, M., & Metzger, A. E. (1997). Gamma-ray burst arrival time localizations: Simultaneous observations by Mars Observer, Compton Gamma Ray Observatory, and Ulysses. Astrophysical Journal, Supplement Series, 110(1), 157-161.
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Abstract: Between 1992 October 4 and 1993 August 1, concurrent coverage by the Compton Gamma Ray Observatory (CGRO), Mars Observer (MO), and Ulysses spacecraft was obtained for 78 gamma-ray bursts (GRBs). Although most of these were below the MO and Ulysses thresholds, nine were positively detected by all three spacecraft, with data quality adequate for quantitative localization analysis. All were localized independently to ∼2° accuracy by the CGRO Burst and Transient Source Experiment (BATSE). We computed arrival-time error boxes with larger dimensions ranging from a few arcminutes to the diameters of the BATSE-only boxes and with smaller dimensions in the arcminute range. Three events are of particular interest: GB 930704 (BATSE 2428) has been described as a possible repeater. The arrival-time information is consistent with that hypothesis, but only just so. The GB 930706 (2431) box, at ∼1′ × 4′, is the only one this small obtained since Pioneer Venus Orbiter (PVO) entered the Venusian atmosphere in 1992 October. Sensitive radio and optical observations of this location were made within 8 and 9 days of the burst, but no counterpart candidates were identified. GB 930801 (2477) is the first GRB that had its localization improved by taking into account BATSE Earth occultation.
Trombka, J. I., Floyd, S. R., Boynton, W. V., Bailey, S., Brückner, J., Squyres, S. W., Evans, L. G., Clark, P. E., Starr, R., Fiore, E., Gold, R., Goldsten, J., & McNutt, R. (1997). Compositional mapping with the NEAR X ray/gamma ray spectrometer. Journal of Geophysical Research E: Planets, 102(E10), 23729-23750.
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Abstract: The X ray/gamma ray spectrometer (XGRS) instrument on board the Near Earth Asteroid Rendezvous (NEAR) spacecraft will map asteroid 433 Eros in the 0.7 keV to 10 MeV energy region. Measurements of the discrete line X ray and gamma ray emissions in this energy domain can be used to obtain both qualitative and quantitative elemental compositions with sufficient accuracy to enable comparison to the major meteorite types. It is believed that Eros is an S-type asteroid, the most common of the near-Earth asteroids. The determination of .whether Eros consists of either differentiated or undifferentiated materials is an important objective of this mission. Observations of Eros during the NEAR mission will contribute significantly to our understanding of the structure and composition of this asteroid. The NEAR spacecraft was successfully launched on February 17, 1996. The NEAR XGRS was turned on during the week of April 7, 1996, and all detector systems operated nominally. Background spectra have been obtained. Copyright 1997 by the American Geophysical Union.
Feldman, W. C., Byrd, R. C., Barraclough, B. L., Nordholt, J. E., Funsten, H. O., Boynton, W. V., Bailey, S. H., & Moersch, J. (1995). Calibration of a space thermal/epithermal neutron detector: The Mars Observer Gamma-Ray Spectrometer anticoincidence shield. Nuclear Inst. and Methods in Physics Research, A, 362(2-3), 561-573.
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Abstract: Procedures used for, and results of, a calibration of the combined anticoincidence shield and neutron detector (A/C-N subsystem) of the Mars Observer Gamma-Ray Spectrometer (MOGRS) are reported. Pulsed energy-dispersed neutrons were generated by directing a chopped deuterium beam from the Los Alamos Van De Graaff accelerator onto a thick Be target enclosed within a specially designed neutron moderating assembly. Absolute energy and angle-dependent detection efficiencies were determined for energies in the range between 0.05 eV and 2 keV and for incident angles between 0° and 150°. A 6Li glass detector and a uranium ion chamber were used as calibrated references for the absolute efficiency determination, which was checked at 0.05 eV using neutrons provided by a large graphite neutron pile, also at Los Alamos. The results are found to be close to those calculated using a Monte Carlo Neutral Particle transport code for an isolated plate of BC454 scintillator (the active sensor of the A/C-N subsystem) with two notable exceptions. First, the measured efficiency below about 0.5 eV is less than the simulated one; second, the measured efficiency decreases more slowly with increasing energy than does the simulated efficiency. Although the actual detector is too complicated to be simulated accurately, we speculate that the relative reduction in efficiency below 0.5 eV may be caused in part by (i) reduced neutron transmission through the material of the sensor head assembly outside of the BC454 pyramid, (ii) reduced effective sensor area because of poor light-collection efficiency around the perimeter of each of the trapezoid plates, and (iii) molecular binding effects of hydrogen in both the BC454 scintillator and in its 1-mm carbon-epoxy cover. We also speculate that the increase in efficiency at about 0.5 eV and the general enhancement of detection efficiency at all higher epithermal energies may be due to the multiple scattering of incident neutrons in materials present in the MOGRS sensor head. © 1995.
Ruzicka, A., Kring, D. A., Hill, D. H., Boynton, W. V., Clayton, R. N., & Mayeda, T. K. (1995). Silica-rich orthopyroxenite in the Bovedy chondrite. Meteoritics, 30(1), 57-70.
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Abstract: A large (>4.5 × 7 × 4 mm) igneous-textured clast in the Bovedy (L3) chondrite is notable for its high bulk SiO2 content (~ 57.5 wt%). It is best described as a silica-rich orthopyroxenite. The oxygen-isotopic composition of the clast is similar, but not identical, to Bovedy and other ordinary chondrites. The closest chemical analogues to the clast are radial-pyroxene chondrules, diogenites, pyroxene-silica objects in ordinary chondrites, and silicates in the IIE iron meteorite Weekeroo Station. The clast crystallized from a siliceous melt that cooled fast enough to prevent complete attainment of equilibrium but slow enough to allow nearly complete crystallization. The texture, form, size and composition of the clast suggest that it is an igneous differentiate from an asteroid or planetesimal that formed in the vicinity of ordinary chondrites. -from Authors
Kring, D. A., Hildebrand, A. R., & Boynton, W. V. (1994). Provenance of mineral phases in the Cretaceous-Tertiary boundary sediments exposed on the southern peninsula of Haiti. Earth and Planetary Science Letters, 128(3-4), 629-641.
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Abstract: Acid-insoluble mineral residua of tektite-bearing Cretaceous-Tertiary boundary sediments in the Beloc Formation of Haiti contain abundant shocked quartz and lesser amounts of shocked plagioclase. The shocked quartz grains typically have 2 or 3 sets of planar deformation features, although grains with up to 15 sets were observed. The proportion of shocked quartz in the boundary sediments increases with stratigraphic height; at least 70 ± 11% of the quartz grains are shocked in the uppermost stratigraphic interval. The proportion of shocked quartz throughout the boundary sediments indicates that these grains were excavated primarily from crystalline silicate units, which may have been covered with a small amount of porous quartz-bearing sediments. Polyhedral and moderately sutured margins in shocked polycrystalline quartz grains, the size of the crystal units in these grains and the presence of shocked plagioclase, indicate these ejecta components were excavated from a target with continental affinities, containing quartzites or metaquartzites and a sialic metamorphic and/or igneous component. Other evidence suggests the target may also have contained a significant amount of calcium carbonate and/or sulfate. The large size and amount of shocked quartz grains deposited in Haiti indicate the crater from which they were excavated was produced in the proto-Caribbean region. © 1994.
Kring, D. A., & Boynton, W. V. (1993). K/T melt glasses [7]. Nature, 363(6429), 503-504.
Boynton, W. V. (1992). Science applications of the Mars Observer gamma ray spectrometer. Journal of Geophysical Research, 97(E5), 7681-7698.
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Abstract: The Mars Observer gamma ray spectrometer will return data related to the elemental composition of Mars. The instrument has both a gamma ray spectrometer and several neutron detectors. The gamma ray spectrometer will return a spectrum nominally every 20 s from Mars permitting a map of the elemental abundances to be made. The neutron detectors, using the fact that the orbital velocity of the Mars Observer spacecraft is similar to the velocity of thermal neutrons, determine both the thermal and epithermal neutron flux. These parameters are particularly sensitive to the concentration of hydrogen in the upper meter of the surface. By combining the results from both techniques it is possible to map the depth dependence of hydrogen in the upper meter as well. -from Authors
Kring, D. A., & Boynton, W. V. (1992). Petrogenesis of an augite-bearing melt rock in the Chicxulub structure and its relationship to K/T impact spherules in Haiti. Nature, 358(6382), 141-144.
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Abstract: Geophysical anomalies on the Yucatan peninsula define a buried circular structure with an approximate diameter of 180 km (refs 1-3). These anomalies, along with stratigraphic and petrological data, including evidence for shock metamorphism, have been used to interpret the structure as an impact crater4. This structure, known as Chicxulub, is particularly interesting because it formed at or near the end of the Cretaceous period, in the geographical region where an impact is believed to have occurred, in large part because of a thick ejecta deposit found on Haiti5. Glassy tektite-like relics in this deposit6-9 are unusually calcic (up to 31 wt% CaO; ref. 7), providing a further circumstantial link with the Chicxulub structure, which penetrates a carbonate and evaporite sequence7,8. Here we strengthen this link by showing that a simple chemical relationship exists between the glasses and an augite-bearing melt rock found within the Chicxulub structure, and argue that the composition of this melt rock could not easily have been produced by volcanic processes.
Hill, D. H., Boynton, W. V., & Haag, R. A. (1991). A lunar meteorite found outside the Antarctic. Nature, 352(6336), 614-617.
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Abstract: OUR knowledge of the Moon's surface composition has come from samples returned by the Apollo and Luna missions, and from eleven lunar meteorites, all of which were discovered in Antarctica1,2. Here we report the discovery of a new lunar meteorite, Calcalong Creek, in a desert region of Australia which is analogous to Antarctica in its ability to preserve meteorites of different types3. On the basis of a diagnostic Fe/Mn ratio of 73-78, and other element abundances, we conclude that Calcalong Creek is a lunar breccia, containing both highland and mare materials. Whereas the Apollo and Luna missions selectively sampled only 5% of the lunar crust, lunar meteorites should provide a random sample4; nevertheless there has been some concern that the Antarctic meteorite population may be biased in some way5. Calcalong Creek will add to our understanding of lunar petrology, and as the first non-Antarctic lunar meteorite, may also shed new light on the transfer of impact ejecta from the Moon to the Earth.
Kring, D. A., & Boynton, W. V. (1991). Altered spherules of impact melt and associated relic glass from the K/T boundary sediments in Haiti. Geochimica et Cosmochimica Acta, 55(6), 1737-1742.
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Abstract: Partially to wholly altered glass spherules produced by impact-induced shock melting have been found in the K/T boundary sediments of Haiti which also contain grains of shocked quartz. The relic glass has an approximately dacitic composition, and although grossly similar in composition to most previously described tektite glasses, it is slightly enriched in Ca and slightly depleted in Si, suggesting the Haitian glass was produced either from a target with a greater fraction of carbonate and anhydrite lithologies and fewer silicate units than the targets from which most other tektites were produced, and/or from one with a significant mafic component. The composition of the glass can best be reconciled with a continental margin terrane, consistent with studies of shocked mineral phases reported elsewhere. The thickness of the deposit in which the impact spherules occur indicates the source of the ejecta was in the proto-Caribbean region. © 1991.
Spitz, A., & Boynton, W. V. (1991). Trace element analysis of ureilites: New constraints on their petrogenesis. Geochimica et Cosmochimica Acta, 55(11), 3417-3430.
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Abstract: Six ureilites (ALHA77257, ALHA81101, ALH82130, PCA82506, Kenna, and Novo Urei) were analyzed using neutron activation analysis for Ca, Sc, Cr, Mn, Fe, Co, Ni, Zn, Ga, REE, W, Re, Os, Ir, and Au. We examined bulk samples as well as acid-treated samples. In the bulk samples the refractory siderophiles' concentrations range from approximately 0.1 to 1.0 times CI chondrites while the volatile siderophiles range from about 0.07 to 0.3 times CI chondrites. Rare earth elements (REEs) in ureilites are quite depleted and display light and heavy rare earth enrichments. The Antarctic meteorites display either much less pronounced v-shaped patterns or no enrichment in the light rare earths at all. In terms of the new trace-element results, ureilites do not fall into the coherent groups that other workers have defined by chemical or petrographic characteristics. Trace elements do provide additional constraints on the models for the petrogenesis of ureilites. In particular, the siderophile element abundances call for simplified models of chemical processing rather than the complex, multistage processing called for in silicate fractionation models. REE concentrations, on the other hand, imply multistage processing to produce the ureilites. None of the ureilite petrogenesis models extant account for the trace element data. These new data and the considerations of them with respect to the proposed ureilite petrogenesis models indicate that the direction of modelling should be toward contemplation of mixtures and how the components we observe in ureilites behave under such conditions. © 1991.
Hildebrand, A. R., & Boynton, W. V. (1990). Proximal cretaceous-tertiary boundary impact deposits in the caribbean. Science, 248(4957), 843-847.
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PMID: 17811835;Abstract: Trace element, isotopic, and mineralogic studies indicate that the proposed impact at the Cretaceous-Tertiary (K-T) boundary occurred in an ocean basin, although a minor component of continental material is required. The size and abundance of shocked minerals and the restricted geographic occurrence of the ejecta layer and impact-wave deposits suggest an impact between the Americas. Coarse boundary sediments at sites 151 and 153 in the Colombian Basin and 5- to 450-meter-thick boundary sediments in Cuba may be deposits of a giant wave produced by a nearby oceanic impact. On the southern peninsula of Haiti, a ∼50-centimeter-thick ejecta layer occurs at the K-T boundary. This ejecta layer is ∼25 times as thick as that at any known K-T site and suggests an impact site within ∼1000 kilometers. Seismic reflection profiles suggest that a buried ∼300-km-diameter candidate structure occurs in the Colombian Basin.
Brearley, A. J., Scott, E. R., Keil, K., Clayton, R. N., Mayeda, T. K., Boynton, W. V., & Hill, D. H. (1989). Chemical, isotopic and mineralogical evidence for the origin of matrix in ordinary chondrites. Geochimica et Cosmochimica Acta, 53(8), 2081-2093.
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Abstract: We report the first combined chemical, isotopic and mineralogical study of fine-grained opaque matrix material from a type 3 ordinary chondrite, Allan Hills A77299 (H3.7). Electron microprobe and instrumental neutron activation analysis of a large matrix lump show that it has a major element composition typical of matrix material in type 3 chondrites. Unlike chondrules, it shows no siderophile element depletions and is remarkably unfractionated relative to CI chondrites, suggesting that it is primitive solar system material. The matrix lump has an unique oxygen isotopic composition which lies below the terrestrial fractionation line and differs markedly from the composition of fine-grained matrix lumps and chondrule rims from Semarkona (Grossman et al., 1987). Transmission electron microscope (TEM) studies of microtomed samples of the fine-grained fraction (1 μm) of pyroxene and olivine, embedded within a groundmass of rounded, fine-grained (
Drake, M. J., & Boynton, W. V. (1988). Partioning of rare earth elements between hibonite and melt and implications for nebular condensation of the rare earth elements. Meteoritics, 23(1), 75-80.
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Abstract: The partitioning of the rare earth elements between hibonite and silicate melt has been investigated at 1470°C in the system calcium tschermak's molecule-diopside. Results suggest that unless the principal phase(s) into which a trace element is dissolving and the activity-composition relationships for that trace element in that phase(s) are known, condensation temperatures based on assumed ideal solution behavior will generally be in error. -from Authors
Wark, D., Boynton, W., Keays, R., & Palme, H. (1987). Trace element and petrologic clues to the formation of forsterite-bearing Ca-Al-rich inclusions in the Allende meteorite. Geochimica et Cosmochimica Acta, 51(3), 607-622.
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Abstract: This work presents new trace element and petrographic data for three forsterite-bearing, Ca-Alrich inclusions from the Allende meteorite: TE, 818a, and 110-A. Such inclusions form a continuum with Type B1 and B2 Ca-Al-rich inclusions (CAIs), and we refer to them as "Type B3" CAIs. Textures, mineral chemistries, crystal-chemically fractionated REE patterns, and other properties suggest that Type B3 crystallized from partly molten evaporative residues. The concentrations of refractory lithophile elements are lower than in Type B1 and Type B2, in approximately inverse proportion to the higher concentrations of Mg and Si in the Type B3's. The refractory trace element abundances of the forsterite-bearing, isotopically anomalous FUN CAIs TE and CG14 suggest that they formed at higher temperatures and under more oxidizing conditions than other Type B CAIs, thus strengthening the previously observed link between relatively oxidized CAI compositions and FUN properties. We also present evidence that 818a was strongly re-heated and modified in the nebula after its initial crystallization: it consists of a core of coarse-grained Ti-Al-pyroxene (Tpx), forsterite, spinel and metal grains and a thick, surrounding mantle of melilite that has been almost totally converted to fine-grained alteration products. In the core, the mean concentrations of refractory lithophiles and siderophiles are similar (both ~ 14 × CI), but in the mantle, the refractory siderophiles are a factor of 2 lower (~ 9 × CI) than the refractory lithophiles (~18 × CI). Because the core and mantle display similar, mineralogically-fractionated REE patterns (both sloping up from La to Lu), the pre-alteration mantle could not have formed during fractional crystallization of the primary CAI nor as a later condensate over the core. A 3-stage formation process is required for 818a: (1) crystallization of the primary CAI rich in Tpx throughout; (2) re-heating and partial volatilization of Mg and Si from the outer portion of the CAI, causing an increase in the concentration of refractory lithophiles, a loss of siderophiles, and converting Tpx to melilite; (3) metasomatic alteration of the melilite-rich mantle. © 1987.
Wilkening, L. L., Boynton, W. V., & Hill, D. H. (1984). Trace elements in rims and interiors of Chainpur chondrules. Geochimica et Cosmochimica Acta, 48(5), 1071-1080.
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Abstract: Trace elements were measured in the rims and interiors of nine chondrules separated from the Chainpur LL-3 chondrite. Whole rock samples of Chainpur and samples of separated rims were also measured. Chondrule rims are moderately enriched in siderophile and volatile elements relative to the chondrule interiors. The enriched volatile elements include the lithophilic volatile element Zn. The moderate enrichment of volatiles in chondrule rims and the lack of severe depletion in chondrules can account for the complete volatile inventory in Chainpur. These results support a three-component model of chondrite formation in which metal plus sulfide, chondrules plus rims and matrix silicates are mixed to form chondrites. © 1984.
Boynton, W. V. (1983). Cosmochemistry of the rare earth elements: meteorite studies.. Rare Earth Element Geochemistry, 63-114.
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Abstract: After a discussion on the condensation of elements from the solar nebula, the REE abundances in Ca,Al-rich inclusions in carbonaceous chondrites are described and interpreted. The normalization values for REE in chondrites are examined at some length and the values of REE in other differentiated meteorites are reported.-R.A.H.
Boynton, W. V., & Hill, D. H. (1983). Composition of bulk samples and a possible pristine clast from Allan Hills A81005.. Geophysical Research Letters, 10(9), 837-840.
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Abstract: Abundances of 35 elements were determined in two bulk samples and a white clast in the Allan Hills A81005 meteorite. High siderophile element content indicates that the sample is a regolith breccia. An Fe/Mn ratio of 77 in this meteorite eliminates parent bodies of known differentiated meteorites as the source of ALHA 81005. The incompatible elements are very similar to those found in most lunar highlands rocks, and provide very strong evidence that the sample is lunar in origin. The clast sample has the trace-element pattern of a lunar anorthosite and is very low in KREEP and siderophile elements. It may be a fragment of a pristine lunar rock. (Authors' abstract)-C.N.
Nozette, S., & Boynton, W. V. (1981). Superheavy elements: An early solar system upper limit for elements 107 to 110. Science, 214(4518), 331-333.
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Abstract: The abundance of samarium-152 in the Santa Clara iron meteorite is found to be 108 × 107 atoms per gram. This quantity, if attributed to fission of a superheavy element with atomic number 107 to 109, limits the amount of superheavy elements in the early solar system to 1.7 × 10-5 times the abundance of uranium-238. For element 110, the limit is 3.4 × 10-5 Copyright © 1981 AAAS.
Boynton, W. V. (1979). Chapter 37F Neutron activation analysis. Handbook on the Physics and Chemistry of Rare Earths, 4, 457-470.
Kerridge, J. F., Mackay, A. L., & Boynton, W. V. (1979). Magnetite in CI carbonaceous meteorites: Origin by aqueous activity on a planetesimal surface. Science, 205(4404), 395-397.
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Abstract: The composition and morphology of magnetite in CI carbonaceous meteorites appear incompatible with a nebular origin. Mineralization on the meteorite parent body is a more plausible mode of formation. The iodine-xenon age of this material therefore dates an episode of secondary mineralization on a planetesimal rather than the epoch of condensation in the primitive solar nebula. Copyright © 1979 AAAS.
Boynton, W. V. (1978). Fractionation in the solar nebula, II. Condensation of Th, U, Pu, and Cm. Earth and Planetary Science Letters, 40(1), 63-70.
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Abstract: Reasonable assumptions concerning activity coefficients allow the calculation of the relative volatility of the actinide elements under conditions expected during the early history of the solar system. Several of the light rare earths have volatilities similar to Pu and Cm and can be used as indicators of the degree of fractionation of these extinct elements. Uranium is considerably more volatile than either Pu or Cm, leading to fractionations of about a factor of 50 and 90 in the Pu/U and Cm/U ratio in the earliest condensates from the solar nebula. Ca, Al-rich inclusions from the Allende meteorite, including the coarse-grained inclusions, have a depletion of U relative to La of about a factor of three, suggesting that these inclusions may have been isolated from the nebular gas before condensation of U was complete. The inclusions, however, can be used to determine solar Pu/U and Cm/U ratios if the rare earth patterns are determined in addition to the other normal measurements. © 1978.
Kallemeyn, G. W., Boynton, W. V., Willis, J., & Wasson, J. T. (1978). Formation of the Bencubbin polymict meteoritic breccia. Geochimica et Cosmochimica Acta, 42(5), 507-515.
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Abstract: The Bencubbin meteorite is a polymict breccia consisting of a host fraction of ~60% metal and ~40% ferromagnesian silicates and a selection of carbonaceous, ordinary and 'enstatite' chondritic clasts. Concentrations of 27 elements were determined by neutron activation in replicate samples of the host silicates and the ordinary and carbonaceous chondritic clasts; 12 elements were determined in the host metal. Compositional data for the ordinary chondrite clast indicate a classification of LL4 ± 1. Refractory element data for the carbonaceous chondrite clast indicate that it belongs to the CI-CM-CO clan; its volatile element abundances are intermediate between those of CM and CO chondrites. Abundances of nonvolatile elements in the silicate host are similar to those in the carbonaceous chondrite clast and in CM chondrites; the rare earths are unfractionated. We conclude that it is not achondritic as previously designated, but chondritic and that it is probably related to the CI-CM-CO clan; its volatile abundances are lower than those in CO chondrites. Oxygen isotope data are consistent with these classifications. Host metal in Bencubbin and in the closely related Weatherford meteorite has low abundances of moderately volatile siderophiles; among iron meteorite groups its nearest relative is group IIIF. We suggest that Bencubbin and Weatherford formed as a result of an impact event on a carbonaceous chondrite regolith. The impact generated an 'instant magma' that trapped and surrounded regolithic clasts to form the polymict breccia. The parent of this 'magma' was probably the regolith itself, perhaps mainly consisting of the so-called 'enstatite' chondrite materials. Accretion of such a variety of materials to a small parent body was probably only possible in the asteroid belt. © 1978.
Boynton, W. V., & Wasson, J. T. (1977). Distribution of 28 elements in size fractions of lunar mare and highlands soils. Geochimica et Cosmochimica Acta, 41(8), 1073-1082.
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Abstract: Four volatile, six siderophile and 18 generally lithophile elements were determined in six sieve fractions of mare soil 15100 and seven sieve fractions of highlands soil 66080; 15100 is a moderately and 66080 a highly mature soil. Two size fractions of 66080 were subjected to leaching with HCI and etching with HF. Leaching removed ca. 25% of the rare earths in both the 500-177 μm and 62-20 μm fractions; the soluble phase, probably a phosphate, is enriched in light rare earths relative to the bulk soil. The leach and etch removed a larger portion of Zn and Cd than expected on the basis of surface concentrations inferred from size distribution data apparently because of selective dissolution of minor volatile-rich phases. Lithophile concentrations in 66080 are nearly independent of grain size. In 15100 decreasing grain sizes show moderately increasing amounts of KREEP and anorthosite related elements, and decreasing amounts of basalt related elements. In 66080 a maximum in siderophile concentration occurs at ca 150 μm, as previously observed in our studies of 61220, 63500 and 65500. This peaking appears to result from a gradual increase with time in the size of metal grains as a result of welding during micrometeorite impacts. The coarse fraction maximum is not observed in the siderophile data for 15100, probably because of the much smaller fluence of extralunar projectiles at the Apollo 15 site. A modest rise in siderophile concentrations in the smallest size fractions of all soils probably results from recondensation of impact-vaporized materials. The concentrations of highly volatile Zn, Cd and In in 15100 and 66080 show a marked increase with decreasing size, but the fine/coarse ratios are about a factor of two lower than those in soils 61220 and 63500. The lower ratio in 66080 results entirely from higher concentrations in the coarser fractions. It appears that this is a reflection of the higher maturity of 66080, and that the volume-correlated component in lunar soils increases with increasing near-surface residency. The high amount of volume-correlated component in 15100 may be related to the more efficient formation of agglutinates in basalt-rich soils. The observed increase in rare gas and volatile metal concentration with decreasing grain size results from an increasing bias in surface exposure of fine grain sizes, probably as a result of the adhesion of smaller to larger grains. © 1977.
Sundberg, L. L., & Boynton, W. V. (1977). Determination of ten trace elements in meteorites and lunar materials by radiochemical neutron activation analysis. Analytica Chimica Acta, 89(1), 127-140.
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Abstract: A procedure is reported for the determination of Ni, Ge, Ru, Au, Ir, Zn, Ga, Cd, In and U in meteorites and lunar materials. The precision in multiple determinations at the 95% confidence level is less than 10% except for gold (15%). Ruthenium and uranium are determined by counting 97Ru and 103Ru x-rays; the chemical yield is determined from 106Ru added before sample dissolution. The activity of 116mIn is determined with improved sensitivity from integral counts in the region 1.5-3.0 MeV on a NaI(TI) detector. © 1977.
Boynton, W. V., Chou, C. -., Bild, R. W., Baedecker, P. A., & Wasson, J. T. (1976). Element distribution in size fractions of Apollo-16 soils: Evidence for element mobility during regolith processes. Earth and Planetary Science Letters, 29(1), 21-33.
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Abstract: Three Apollo-16 soils, 61220, 63500 and 65500, having diverse properties were separated into six size fractions and analyzed for 8 volatiles and siderophiles. Relative concentrations of an additional 20 elements were determined in 61220 and 63500. The volatile elements Cd, Zn, In and Ga increase in concentration with decreasing grain size; in the finest fractions the increase is roughly parallel to the increase in specific surface area, and a surface correlation is inferred. The total increase from coarsest (177-500 μm) to finest (
Boynton, W., Starzyk, P., & Schmitt, R. (1976). Chemical evidence for the genesis of the ureilites, the achondrite Chassigny and the nakhlites. Geochimica et Cosmochimica Acta, 40(12), 1439-1447.
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Abstract: Major element and REE, Cr, Sc, V, Ni, Co, Ir, Au, Sr, Ba abundances were determined in three ureilites and the unique achondrite, Chassigny. Chondritic-normalized REE abundance patterns for the ureilites are v-shaped, similar to pallasites, indicating a possible deep-seated origin. The lithophile trace element abundances and v-shaped REE patterns of the ureilites are consistent with a two-stage formation process, the first of which is an extensive partial melting of chondrite-like matter to yield ureilite precursors in the residual solid, which is enriched in Lu relative to La. The second step consists of an admixture of small and variable amounts of material enriched in the light REE. Such contaminating material may be magmas derived from the first formed melt of partial melting of chondrite-like matter. In contrast to the ureilites, Chassigny has a chondritic-normalized REE pattern which decreases smoothly from La(1.8 × ) to Lu(0.4 × ) and is parallel to and ~0.25 × the REE pattern in the nakhlitic achondrites. The composition of the magma from which Chassigny crystallized was highly enriched in the light REE; e.g. chondritic normalized La/Lu ~ 7. The similarity in the fractionated REE patterns (no Eu anomalies) for the olivine-pyroxene Chassigny and for the nakhlites suggests a genetic relationship. Siderophile trace element relationships in ureilites can be interpreted by three components: (1) ultramafic silicates enriched in Co relative to Ni, (2) an indigenous metal phase remaining after the partial melting event, and (3) a component of the carbon-rich vein material added after the partial melting. © 1976.
Henderson, P., Fishlock, S. J., Laul, J. C., Cooper, T. D., Conard, R. L., Boynton, W. V., & Schmitt, R. A. (1976). Rare earth element abundances in rocks and minerals from the Fiskenaesset Complex, West Greenland. Earth and Planetary Science Letters, 30(1), 37-49.
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Abstract: Rare earth element (REE) abundances determined by activation analysis in rocks, plagioclase and mafic separates from the Fiskenaesset Complex are presented together with data on major and trace elements in the minerals. The REE data for the rocks and plagioclases are distinct from those of many other anorthositic complexes and the abundances are some of the lowest recorded for plagioclase from terrestrial anorthosites. The bulk and trace element compositions of the Fiskenaesset plagioclases show a number of similarities to those of lunar plagioclases. The plagioclases show a positive Eu anomaly of about 10 and a depletion in the heavy REE relative to the light ones. The mafic separates are enriched in the heavy REE relative to the light ones, and show no Eu anomaly except in one sample with a positive anomaly not attributable to plagioclase contamination. It is estimated, from experimental partition coefficient data, that the REE pattern in the magma at an early stage of fractionation was La (17×) to Lu (0.7× chondrites) with a possible positive Eu anomaly. This highly fractionated REE pattern may be attributed to partial melting of a garnet-bearing source. © 1976.
Boynton, W. V. (1975). Fractionation in the solar nebula: condensation of yttrium and the rare earth elements. Geochimica et Cosmochimica Acta, 39(5), 569-584.
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Abstract: The condensation of Y and the rare earth elements (REE) from the solar nebula may be controlled by thermodynamic equilibrium between gas and condensed solids. Highly fractionated REE patterns may result if condensates are removed from the gas before condensation is complete. It is found that the fractionation is not a smooth function of REE ionic radius but varies in an extremely irregular pattern. Both Yb and Eu are predicted to be extremely depleted in the early condensate without the requirement of condensation in the divalent state. The model is discussed with respect to a highly fractionated pattern observed by Tanaka and Masuda (Icarus 19, 523-530 1973), in a pink Ca-Al-rich inclusion from the Allende meteorite and can account for the abundances of each REE determined. According to the model this inclusion represents a condensate from a previously fractionated gas rather than from a gas of solar composition. Before the condensation of this inclusion, an earlier condensate was formed and was removed from equilibrium with the gas. © 1975.
Wasson, J. T., Boynton, W. V., Chou, C., & Baedecker, P. A. (1975). Compositional evidence regarding the influx of interplanetary materials onto the lunar surface. The Moon, 13(1-3), 121-141.
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Abstract: Siderophilic element/Ir ratios are higher in mature lunar soils from highlands sites than in those from mare sites. We infer that the population of materials responsible for the early intense bombardment of the Moon had high ratios, and that the population responsible for the essentially constant flux has low ratios. No group of chondrites has siderophile/Ir ratios identical to those in the mare or highlands soils; CM chondrites are the most similar, and CM-like materials may account for a major fraction of Earth-crossing materials during the past 3.7 b.y. Siderophile/Ir ratios may be used to determine the amount of highlands regolith in soils or breccias from the mare-highlands interface areas (Apollo 15 and 17), and to infer the time of formation of highlands breccias whose sideropbiles originated in mature soils. Arguments are summarized against the viewpoint that the siderophiles in most highlands breccias originated in basin-forming projectiles. Differences in mature soil siderophile concentrations at Apollo 14 and 16 indicate a substantially greater concentration at the latter site immediately following the Imbrium event. Siderophile concentrations are used to estimate mean regolith depths at the landing sites; as relative values these are more precise than estimates based on seismic or crater observations. The longlived flux is calculated to be 2.9 g cm-2 b.y.-1 averaged over the past 3.7 b.y. A consideration of the relationship between mass fluence and time indicates that the mass flux decreased with a half-life of about 40 m.y. immediately following the Imbrium event. © 1975 D. Reidel Publishing Company.

Proceedings Publications

Barnouin}, O., Palmer, E., Gaskell, B., Weirich, J., Daly, M., Seabrook, J., Johnson, C., Al Asad, M., Susorney, H., Perry, M., Daly, R., Bierhaus, E., Boynton, W., Dellagiustina, D., Ernst, C., Espiritu, R., Nair, H., Mazarico, E., Nguyen, L., , Neumann, G., et al. (2019, Mar). Investigating the Shape of Bennu. In Lunar and Planetary Science Conference.
Chesley, S. R., Adam, C., Antreasian, P., Bos, B. J., Boynton, W. V., Brozovi{\'c}, M., Carcich, B. T., Davis, A. B., Emery, J. P., Farnocchia, D., French, A. S., Hergenrother, C., Jacobson, R. A., Lauretta, D. S., Leonard, J., Lessac-Chenen, E., Liounis, A. J., McMahon, J., Moreau, M. C., , Nolan, M. C., et al. (2019, Jun). Trajectory estimation for Bennu's particles. In AAS/Division of Dynamical Astronomy Meeting, 51.
Daly}, M., Barnouin, O., Seabrook, J., Johnson, C., Al Asad, M., Nolan, M., Boynton, W., Lauretta, D., & Team, {. (2019, Mar). The OSIRIS-REx Laser Altimeter at \>7km from Asteroid 101955 Bennu. In Lunar and Planetary Science Conference.
Garcia, A., Sutter, B., Archer, P., Niles, P., Stein, T., Boynton, W., & Hamara, D. (2019, Mar). The 2008 Mars Phoenix Lander Thermal and Evolved Gas Analyzer (TEGA) Dataset: Placing Easily Interpretable Evolved Gas Data on the Planetary Data System (PDS). In Lunar and Planetary Science Conference.
Hergenrother, C., Adam, C., Antreasian, P., Al, A. M., Balram-Knutson, S., Ballouz, R., Bartels, A., Barucci, M. A., Becker, K., Bland, P., Bos, B., Boynton, W., Brozovi{\'c}, M., Burke, K., Carpenter, R., Carcich, B., Chesley, S., DellaGiustina, D., Drouet, d. C., & Lauretta, D. (2019, Sep). (101955) Bennu is an Active Asteroid. In EPSC-DPS Joint Meeting 2019, 2019.
Lauretta, D., Al, A. M., Ballouz, R., Barnouin, O., Bierhaus, E., Boynton, W., Breitenfeld, L., Calaway, M., Chojnacki, M., Christensen, P., Clark, B., Connolly, H., d'Aubigny, C., Daly, M., Daly, R., Delbo, M., DellaGiustina, D., Dworkin, J., Emery, J., , Enos, H., et al. (2019, Mar). OSIRIS-REx Arrives at Asteroid (101955) Bennu: Exploration of a Hydrated Primitive Near-Earth Asteroid. In Lunar and Planetary Science Conference.
Litvak, M., Mitrofanov, I., Malakhov, A., Sanin, A., & Boynton, W. (2019, Mar). Joint Observations of Martian Seasonal Cycle from HEND/Odyssey and FREND/TGO. In Lunar and Planetary Science Conference.
Tate, C., Moersch, J., Mitrofanov, I., Litvak, M., Bellutta, P., Boynton, W., Cagle, N., Ehresmann, B., Fedosov, F., Golovin, D., Hardgrove, C., Harshman, K., Hassler, D., Jun, I., Kozyrev, A., Lisov, D., Malakhov, A., Mischna, M., Nikiforov, S., , Sanin, A., et al. (2019, Mar). Mars Science Laboratory Dynamic Albedo of Neutrons Passive Mode Data and Results from Sols 753 to 1292: Pahrump Hills to Naukluft Plateau. In Lunar and Planetary Science Conference.
Barnouin, O., Daly, M., Palmer, E., Johnson, C., Perry, M., Gaskell, R., Bierhaus, E., Boynton, W., Craft, K., Ernst, C., Espiritu, R., Nair, H., Mazarico, E., Nguyen, L., Neumann, G., Philpott, L., Roberts, J., Seabrook, J., Susorney, H., , Nolan, M., et al. (2018, mar). Altimetry Efforts at Bennu. In Lunar and Planetary Science Conference, 49.
Livengood, T., Chin, G., Mitrofanov, I., Boynton, W., Hamara, D., Harshman, K., Litvak, M., McClanahan, T., Sagdeev, R., Sanin, A., Starr, R., & Su, J. (2018, mar). Lunar Thermal Neutron Emission Mapped by the LRO/LEND Doppler Detectors. In Lunar and Planetary Science Conference, 49.
McClanahan, T., Mitrofanov, I., Boynton, W., Chin, G., Starr, R., Parsons, A., Livengood, T., Litvak, M., Harshman, K., Hamara, D., & Su, J. (2018, mar). Recalibrated South Polar Observations from the Lunar Exploration Neutron Detector Onboard the Lunar Reconnaissance Orbiter. In Lunar and Planetary Science Conference, 49.
Parsons, A., McClanahan, T., Mitrofanov, I., Boynton, W., Chin, G., Litvak, M., Livengood, T., Sanin, A., Starr, R., Su, J., Hamara, D., & Harshman, K. (2018, mar). Studies of Recalibrated Observations from the Lunar Reconnaissance Orbiter's Lunar Exploration Neutron Detector. In Lunar and Planetary Science Conference, 49.
Su, J., Sagdeev, R., Boynton, W., Chin, G., Livengood, T., McClanahan, T., Parsons, A., Starr, R., Hamara, D., & Harshman, K. (2018, mar). On-Orbit Calibration of Lunar Exploration Neutron Detectors On Board Lunar Reconnaissance Orbiter and Characterization of GCR Particle, Secondary Particle, and Lunar Neutron Components. In Lunar and Planetary Science Conference, 49.
Sutter, B., Archer, P., McAdam, A., Niles, P., Navarro-Gonz{\'alez}, R., Fairen, A., Boynton, W., Hamara, D., Ming, D., Eignebrode, J., & Mahaffy, P. (2018, mar). Comparing the Detection of Carbon at the Phoenix Lander and Mars Science Laboratory Rover Landing Sites. In Lunar and Planetary Science Conference, 49.
Lauretta, D. S., Nolan, M. C., Boynton, W. V., Bierhaus, E., Taylor, A., Aslam, I., Brunet, C., Gaudreau, D., Haltigin, T., Cunningham, G., Johnson, C. L., Seabrook, J., Dickinson, C., Barnouin, O. D., & Daly, M. G. (2017, mar). The OSIRIS-REx Laser Altimeter. In Lunar and Planetary Science Conference, 48.
{Litvak}, M., {Sanin}, A., {Mitrofanov}, I., {Boynton}, W., {Bakhtin}, B., {Bodnarik}, J., {Chin}, G., {Evans}, L., {Livengood}, T., {Malakhov}, A., {McClanahan}, T., {Mokrousov}, M., {Starr}, R., , R. (2016, mar). Water in Lunar Craters from LRO Observations. In Lunar and Planetary Science Conference, 47.
{Livengood}, T., {Chin}, G., {Mitrofanov}, I., {Boynton}, W., {Bodnarik}, J., {Evans}, L., {Harshman}, K., {Litvak}, M., {McClanahan}, T., {Murray}, J., {Sagdeev}, R., {Sanin}, A., {Starr}, R., , J. (2016, mar). Constructing Lunar Neutron Flux Maps with LRO/LEND Natural Resolution. In Lunar and Planetary Science Conference, 47.
{McClanahan}, T., {Mirofanov}, I., {Boynton}, W., {Chin}, G., {Livengood}, T., {Su}, J., {Sagdeev}, R., {Parsons}, A., {Evans}, L., {Starr}, R., {Hamara}, D., {Bodnarik}, J., {Williams}, J., {Mazarico}, E., {Litvak}, M., {Sanin}, A., , J. (2016, apr). Diurnally modulating neutron flux in the Moon's high-latitudes: Evidence for transported hydrogen volatiles and/ or complex regolith compositions in topographic slopes. In EGU General Assembly Conference Abstracts, 18.
{McClanahan}, T., {Mitrofanov}, I., {Boynton}, W., {Chin}, G., {Parsons}, A., {Starr}, R., {Evans}, L., {Sanin}, A., {Litvak}, M., {Livengood}, T., {Sagdeev}, R., {Su}, J., {Murray}, J., {Bodnarik}, J., {Hamara}, D., , J. (2016, mar). Diurnally Modulating Neutron Flux in the Moon's High-Latitudes: Evidence for Transported Hydrogen Volatiles and/or Complex Regolith Compositions in Topographic Slope. In Lunar and Planetary Science Conference, 47.
{Sanin}, A., {Mitrofanov}, I., {Litvak}, M., {Boynton}, W., {Bodnarik}, J., {Hamara}, D., {Harshman}, K., {Chin}, G., {Evans}, L., {Livengood}, T., {McClanahan}, T., {Sagdeev}, R., , R. (2016, apr). How LEND sees the water on the Moon. In EGU General Assembly Conference Abstracts, 18.
{Tate}, C., {Moersch}, J., {Ehresmann}, B., {Jun}, I., {Hardgrove}, C., {Mischna}, M., {Litvak}, M., {Mitrofanov}, I., {Boynton}, W., {Fedosov}, F., {Golovin}, D., {Hassler}, D., {Harshman}, K., {Kozyrev}, A., {Malakhov}, A., {Milliken}, R., {Mokrousov}, M., {Nikiforov}, S., {Sanin}, A., , A. (2016, mar). Water Equivalent Hydrogen Abundances from Bradbury Landing to Amargosa Valley Using Passive Mode Data from the MSL Dynamic ALbedo of Neutrons Experiment. In Lunar and Planetary Science Conference, 47.
{Dworkin}, J., {Adelman}, L., {Ajluni}, T., {Andronikov}, A., {Bartels}, A., {Boynton}, W., {Brucato}, J., {Burton}, A., {Callahan}, M., {Clark}, B., {Connolly}, H., {Elsila}, J., {Enos}, H., {Everett}, D., {Franchi}, I., {Fust}, J., {Hendershot}, J., {Glavin}, D., {Harris}, J., , {Hildebrand}, A., et al. (2015, mar). "{OSIRIS-REx is a Pathfinder for Contamination Control for Cost Controlled Missions in the 21st Century}". In Lunar and Planetary Science Conference, 46.
{Karunatillake}, S., {Wray}, J., {Gasnault}, O., {McLennan}, S., {Rogers}, A., {Squyres}, S., {Boynton}, W., {Skok}, J., {Button}, N., , L. (2015, mar). "{Latitudinal Variation in the Association of H2O with Sulfur in Martian Soil}". In Lunar and Planetary Science Conference, 46.
{Lim}, L., {Starr}, R., {Evans}, L., {Parsons}, A., {Zolensky}, M., , W. (2015, mar). "{Measuring Bulk Carbon, Hydrogen, and Sulfur from Orbit: Modeling Gamma-Ray Spectroscopy of Carbonaceous Asteroids}". In Lunar and Planetary Science Conference, 46.
{Litvak}, M., {Mitrofanov}, I., {Boynton}, W., {Fedosov}, F., {Golovin}, D., {Harshman}, K., {Hardgrove}, C., {Jun}, I., {Kozyrev}, A., {Kuzmin}, R., {Lisov}, D., {Malakhov}, A., {Milliken}, R., {Mischna}, M., {Moersch}, J., {Mokrousov}, M., {Nikiforov}, S., {Sanin}, A., {Starr}, R., , {Tate}, C., et al. (2015, mar). "{DAN Observations of Subsurface Water at Pahrump Hills, Lower Mt. Sharp/Gale Crater}". In Lunar and Planetary Science Conference, 46.
{McClanahan}, T., {Mitrofanov}, I., {Boynton}, W., {Chin}, G., {Parsons}, A., {Starr}, R., {Evans}, L., {Sanin}, A., {Litvak}, M., {Livengood}, T., {Sagdeev}, R., {Su}, J., {Murray}, J., {Bodnarik}, J., {Hamara}, D., , K. (2015, mar). "{Epithermal Neutron Evidence for a Diurnal Surface Hydration Process in the Moon's High Latitudes}". In Lunar and Planetary Science Conference, 46.
{Newsom}, H., {Gordon}, S., {Jackson}, R., {Wiens}, R., {Lanza}, N., {Cousin}, A., {Clegg}, S., {Sautter}, V., {Bridges}, J., {Mangold}, N., {Gasnault}, O., {Maurice}, S., {D'Uston}, C., {Berger}, G., {Forni}, O., {Lasue}, J., {Meslin}, P., {Clark}, B., {Anderson}, R., , {Gellert}, R., et al. (2015, mar). "{Regional Context of Soil and Rock Chemistry at Gale and Gusev Craters, Mars}". In Lunar and Planetary Science Conference, 46.
{Noll}, K., {McFadden}, L., {Rhoden}, A., {Lim}, L., {Boynton}, W., {Carter}, L., {Collins}, G., {Englander}, J., {Goossens}, S., {Grundy}, W., {Li}, J., {Mottola}, S., {Oberst}, J., {Orosei}, R., {Parsons}, A., {Preusker}, F., {Reuter}, D., {Simon}, A., {Thomas}, C., , {Walsh}, K., et al. (2015, mar). "{DARe: Dark Asteroid Rendezvous}". In Lunar and Planetary Science Conference, 46.
{Parsons}, A., {Boynton}, W., {Evans}, L., {Hamara}, D., {Harshman}, K., {Lim}, L., , R. (2015, mar). "{Use of the Mars Odyssey High Purity Germanium (HPGe) Gamma Ray Detector Design for Orbital Asteroid Measurements}". In Lunar and Planetary Science Conference, 46.
{Sanin}, A., {Mitrofanov}, I., {Litvak}, M., {Bodnarik}, J., {Boynton}, W., {Chin}, G., {Evans}, L., {Golovin}, D., {Harshman}, K., {Livengood}, T., {Malakhov}, A., {Mokrousov}, M., {McClanahan}, T., {Sagdeev}, R., {Starr}, R., , A. (2015, apr). "{Observation of lunar neutron albedo along the 24th Solar cycle}". In EGU General Assembly Conference Abstracts, 17.
{Sanin}, A., {Mitrofanov}, I., {Litvak}, M., {Bodnarik}, J., {Boynton}, W., {Chin}, G., {Evans}, L., {Golovin}, D., {Harshman}, K., {Livengood}, T., {Malakhov}, A., {Mokrousov}, M., {McClanahan}, T., {Sagdeev}, R., {Starr}, R., , A. (2015, mar). "{Observation of Lunar Neutron Albedo During Solar Cycle 24 Using LEND Data}". In Lunar and Planetary Science Conference, 46.
{Tate}, C., {Moersch}, J., {Jun}, I., {Hardgrove}, C., {Mischna}, M., {Litvak}, M., {Varenikov}, V., {Mitrofanov}, I., {Boynton}, W., {DeFlores}, L., {Drake}, D., {Fedosov}, F., {Golovin}, D., {Harshman}, K., {Kozyrev}, A., {Lisov}, D., {Malakhov}, A., {Milliken}, R., {Mokrousov}, M., , {Nikiforov}, S., et al. (2015, mar). "{Thermal Conductivity of the Near-Surface Martian Regolith Derived from Variations in MSL Passive Neutron Counts and Ground Temperature}". In Lunar and Planetary Science Conference, 46.
{Chin}, G., {Sagdeev}, R., {Millikh}, G., {Usikov}, D., {Su}, J., {Boynton}, W., {Golovin}, D., {Harshman}, K., {Litvak}, M., {Mitrofanov}, I., {McClanahan}, T., {Livengood}, T., {Evans}, L., , R. (2014, oct). Determining the Magnitude of Neutron and Galactic Cosmic Ray (GCR) Fluxes at the Moon Using the Lunar Exploration Neutron Detector (LEND) During the Historic Space-Age Era of High GCR Flux. In Annual Meeting of the Lunar Exploration Analysis Group, 1820.
{Daly}, M., {Barnouin}, O., {Johnson}, C., {Bierhaus}, E., {Seabrook}, J., {Dickinson}, C., {Haltigin}, T., {Gaudreau}, D., {Brunet}, C., {Cunningham}, G., {Lauretta}, D., {Boynton}, W., , E. (2014, jul). The OSIRIS-REx laser altimeter (OLA): Development progress. In Asteroids, Comets, Meteors 2014.
{Lim}, L., {Starr}, R., {Evans}, L., {Parsons}, A., {Zolensky}, M., {Boynton}, W., , C. (2014, nov). Orbital Measurement of Bulk Carbon, Hydrogen, Oxygen, and Sulfur of Carbonaceous Asteroids via High Energy Resolution Gamma-Ray Spectroscopy. In AAS/Division for Planetary Sciences Meeting Abstracts, 46.
{Litvak}, M., {Mitrofanov}, I., {Sanin}, A., {Lisov}, D., {Behar}, A., {Boynton}, W., {Deflores}, L., {Fedosov}, F., {Golovin}, D., {Hardgrove}, C., {Harshman}, K., {Jun}, I., {Kozyrev}, A., {Kuzmin}, R., {Malakhov}, A., {Mischna}, M., {Moersch}, J., {Mokrousov}, M., {Nikiforov}, S., , {Shvetsov}, V., et al. (2014, jul). Measurements of Subsurface Water Distribution in Current and Future Orbital and Landing Missions: Comparison Between Mars Odyssey, MSL Curiosity and ExoMars Missions. In Eighth International Conference on Mars, 1791.
{Livengood}, T., {Chin}, G., {Sagdeev}, R., {Mitrofanov}, I., {Boynton}, W., {Evans}, L., {Litvak}, M., {McClanahan}, T., {Sanin}, A., {Starr}, R., , J. (2014, oct). Diurnally Variable Hydrogen-Bearing Volatiles at the Moon's Equator: Evidence, Concentration, Transport, Implications. In Annual Meeting of the Lunar Exploration Analysis Group, 1820.
{McClanahan}, T., {Mitrofanov}, I., {Boynton}, W., {Chin}, G., {Evans}, L., {Starr}, R., {Livengood}, T., {Sagdeev}, R., {Parsons}, A., {Su}, J., {Murray}, J., {Sanin}, A., {Litvak}, M., {Harshman}, K., {Hamara}, D., , J. (2014, oct). Epithermal Neutrons, Illumination, Spatial Scale and Topography: A Correlative Analysis of Factors Influencing the Detection of Slope Hydration Using LRO's Lunar Exploration Neutron Detector. In Annual Meeting of the Lunar Exploration Analysis Group, 1820.
{Mitrofanov}, I., {Litvak}, M., {Sanin}, A., {Lisov}, D., {Behar}, A., {Boynton}, W., {Deflores}, L., {Fedosov}, F., {Golovin}, D., {Hardgrove}, C., {Harshman}, K., {Jun}, I., {Kozyrev}, A., {Kuzmin}, R., {Malakhov}, A., {Mischna}, M., {Moersch}, J., {Mokrousov}, M., {Nikiforov}, S., , {Shvetsov}, V., et al. (2014, jul). Content of Hydrogen and Neutron Absorbing Elements at Gale Crater Measured by DAN Instrument onboard the Curiosity Mars Rover. In Eighth International Conference on Mars, 1791.
{Mitrofanov}, I., {Litvak}, M., {Sanin}, A., {Starr}, R., {Lisov}, D., {Kuzmin}, R., {Behar}, A., {Boynton}, W., {Hardgrove}, C., {Harshman}, K., {Jun}, I., {Miliken}, R., {Mischna}, M., {Moersch}, J., , C. (2014, may). DAN measures water in the soil of the Gale crater: new results from Curiosity. In EGU General Assembly Conference Abstracts, 16.
{Sanin}, A., {Mitrofanov}, I., {Litvak}, M., {Boynton}, W., {Chin}, G., {Evans}, L., {Golovin}, D., {Harshman}, K., {Livengood}, T., {McClanahan}, T., {Malakhov}, A., {Mokrousov}, M., {Sagdeev}, R., , R. (2014, may). Hydrogen concentration in Lunar South Circumpolar Region according to LEND data. In EGU General Assembly Conference Abstracts, 16.
{Tanquary}, H., {Sahr}, E., {Habib}, N., {Hawley}, C., {Weber}, N., {Boynton}, W., {Kinney-Spano}, E., , D. (2014, nov). Optimization of Sample Site Selection Imaging for OSIRIS-REx Using Asteroid Surface Analog Images. In AAS/Division for Planetary Sciences Meeting Abstracts, 46.
{Tate}, C., {Moersch}, J., {Jun}, I., {Hardgrove}, C., {Mischna}, M., {Litvak}, M., {Mitrofanov}, I., {Varenikov}, A., {Behar}, A., {Boynton}, W., {Deflores}, L., {Fedosov}, F., {Golovin}, D., {Harshman}, K., {Kozyrev}, A., {Malakhov}, A., {Milliken}, R., {Mokrousov}, M., {Nikiforov}, S., , {Sanin}, A., et al. (2014, jul). Water Equivalent Hydrogen Abundances Along the First 402 Sols of Curiosty's Traverse Using Passive Data from the Dynamic Albedo of Neutrons Experiment. In Eighth International Conference on Mars, 1791.
Hurley, K., Mitrofanov, I., Golovin, D., Litvak, M., Sanin, A., Boynton, W., Fellows, C., Harshman, K., Starr, R., Golenetskii, S., Aptekar, R., Mazets, E., Pal'shin, V., Frederiks, D., Svinkin, D., Smith, D., Hajdas, W., von, K. A., Zhang, X., , Rau, A., et al. (2012, May). The Interplanetary Network Database. In Proceedings of the Gamma-Ray Bursts 2012 Conference (GRB 2012).
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Pal'shin, V., Hurley, K., Goldsten, J., Mitrofanov, I., Boynton, W., von, K. A., Cummings, J., Feroci, M., Aptekar, R., Frederiks, D., Golenetskii, S., Mazets, E., Svinkin, D., Golovin, D., Litvak, M., Sanin, A., Fellows, C., Harshman, K., Starr, R., , Rau, A., et al. (2012, May). GRB 080407: an ultra-long burst discovered by the IPN. In Proceedings of the Gamma-Ray Bursts 2012 Conference (GRB 2012).
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Poster Presentations

Bodnarik, J., Mitrofanov, I., Boynton, W., Hamara, D., Harshman, K., Gardner, A., Chin, G., McClanahan, T., Starr, R., Evans, L., Sanin, A., Litvak, M., & Livengood, T. (2014, March). LEND CSETN Circular and Elliptical Orbital Data Processing. 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 2925; LPI Contribution No. 1777
Chin, G., Sagdeev, R., Milikh, G., Usikov, D., Su, J., Boynton, W., Golovin, D., Harshman, K., Litvak, M., Mitrofanov, I., McClanahan, T., Livengood, T., Evans, L., Sanin, A., & Starr, R. (2014, March). Determining the Magnitude of Neutron and Galactic Cosmic Ray (GCR) Fluxes at the Moon Using the Lunar Exploration Neutron Detector (LEND) During the Historic Space-Age Era of High GCR Flux. 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 1704; LPI Contribution No. 1777
Hardgrove, C., Moersch, J., Mitrofanov, I., Litvak, M., Behar, A., Boynton, W., Deflores, L., Drake, D., Fedosov, F., Golovin, D., Jun, I., Harshman, K., Kozyrev, A., Malakhov, A., Milliken, R., Kuzmin, R., Mischna, M., Mokrousov, M., Nikiforov, S., , Sanin, A., et al. (2014, March). Modeling of Mars Science Laboratory Curiosity's Dynamic Albedo of Neutrons Instrument Data Using Elemental Geochemistry. 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 1664; LPI Contribution No. 1777
Hong, J., Grindlay, J., Romaine, S., Ramsey, B., Binzel, R., Boynton, W., Georenstein, P., Kraft, R., Kenter, A., Elvis, M., Wolk, S., Smith, R., Lim, L., Lisse, C., Branduardi-Raymont, G., Allen, B., & Lee, J. (2014, March). Miniature Lightweight X-Ray Optics (MiXO) for Solar System Exploration. 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 2203; LPI Contribution No. 1777
Kuzmin, R., Mitrofanov, I., Litvak, M., Sanin, A., Hardgrove, C., Tate, C., Behar, A., Boynton, W., DeFlores, L., Fedosov, F., Golovin, D., Harshman, K., Jun, I., Kozyrev, A., Malakhov, A., Michna, M., Moersch, J., Mokrousov, M., Nikiforov, S., , Shvetsov, V., et al. (2014, March). Mars: Looking for Link Between Local Micro-Morphology Diversity Along the Rover Curiosity Traverse in the Gale Crater and Variability of the DAN Active Mode Measurements. 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 1240; LPI Contribution No:. 1777
Litvak, M., Mitrofanov, I., Boynton, W., Fedosov, F., Golovin, D., Harshman, K., Jun, I., Kozyrev, A., Kuzmin, R., Lisov, D., Malakhov, A., Mokrousov, M., Nikiforov, S., Sanin, A., Shvecov, V., & Starr, R. (2014, March). Following Subsurface Water Distribution in Past, Current and Future Mars Orbital and Surface Missions Based on the Neutron Spectroscopy Observations. 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 1842; LPI Contribution No. 1777
Livengood, T., Boynton, W., Chin, G., Evans, L., Litvak, M., McClanahan, T., Mitrofanov, I., Sagdeev, R., Sanin, A., Starr, R., & Su, J. (2014, March). Neutron Remote-Sensing at the Moon: Modeling the Empirical Variation with Altitude of Neutron Flux for the Lunar Exploration Neutron Detector (LEND). 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 2592; LPI Contribution No. 1777
Livengood, T., Chin, G., Sagdeev, R., Mitrofanov, I., Boynton, W., Evans, L., Litvak, M., McClanahan, T., Sanin, A., & Starr, R. (2014, March). Evidence for Diurnally Varying Hydration at the Moon's Equator from the Lunar Exploration Neutron Detector (LEND). 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 1507; LPI Contribution No. 1777
McClanahan, T., Mitrofanov, I., Boynton, W., Chin, G., Evans, L., Starr, R., Sanin, A., Livengood, T., Sagdeev, R., Bodnarik, J., Hamara, D., Nandikotkur, G., & Su, J. (2014, March). Upper-Latitude Hydration of the Moon's Southern Poleward-Facing Slopes. 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 2931; LPI Contribution No. 1777
Mitrofanov, I., Litvak, M., Sanin, A., Starr, R., Lisov, D., Kuzmin, R., Behar, A., Boynton, W., Hardgrove, C., Harshman, K., Jun, I., Miliken, R., Mishna, M., Moersch, J., & Tate, C. (2014, March). Content of Water and Chlorine in the Martian Soil Along the Traverse of "Curiosity", as Measured by the Active Neutron Instrument DAN Onboard the Rover. 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 1436; LPI Contribution No. 1777
Sanin, A., Mitrofanov, I., Litvak, M., Boynton, W., Chin, G., Evans, L., Golovin, D., Harshman, K., Livengood, T., McClanahan, T., Malakhov, A., Mokrousov, M., Sagdeev, R., & Starr, R. (2014, March). Estimation of Hydrogen Concentration in Lunar South Polar Regions. 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 1358; LPI Contribution No. 1777
Su, J., Sagdeev, R., Boynton, W., Chin, G., Evans, L., Litvak, M., Livengood, T., McClanahan, T., Mitrofanov, I., Murray, J., Sanin, A., Starr, R., & Usikov, D. (2014, March). Fine Structure Neutron Supression Structure in Lunar Polar Region. 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 2329; LPI Contribution No. 1777
Tate, C., Moersch, J., Jun, I., Hardgrove, C., Mischna, M., Litvak, M., Varenikov, A., Mitrofanov, I., Behar, A., Boynton, W., Deflores, L., Fedosov, F., Golovin, D., Harshman, K., Kozyrev, A., Malakhov, A., Milliken, R., Mokrousov, M., Nikiforov, S., , Sanin, A., et al. (2014, March). Water Equivalent Hydrogen Abundances Along the First 200 Sols of Curiosity's Traverse Using Passive Data from the Dynamic Albedo of Neutrons Experiment. 45th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/17-21/14; Page: 1173; LPI Contribution No. 1777
Boynton, W. V., Newsom, H., & et, a. l. (2013, March). Regional and Global Context of Soil and Rock Chemistry from Chemcam and Apxs at Gale Crater. 44th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/18-22/13; Page: 1832; LPI Contribution No. 1719
Chin, G., Sagdeev, R., Boynton, W., Mitrofanov, I., Milikh, G., Su, J., Livengood, T., McClanahan, T., Evans, L., Starr, R., litvak, M., & Sanin, A. (2013, Fall). Determining the Magnitude of Neutron and Galactic Cosmic Ray (GCR) Fluxes at the Moon using the Lunar Exploration Neutron Detector during the Historic Space-Age Era of High GCR Flux. American Geophysical Union, Fall Meeting 2013.
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Abstract #P54B-08
Hardgrove, C., Moersch, J., Drake, D., Mitrofanov, I., Litvak, M., Behar, A., Boynton, W., Deflores, L., Fedosov, F., Golovin, D., Jun, I., Harshman, K., Kozyrev, A., Malakhov, A., Milliken, R., Kuzmin, R., Mischna, M., Mokrousov, M., Nikiforov, S., , Sanin, A., et al. (2013, March). Chlorine and Hydrogen Contents from the First 90 Sols of MSL DAN Active Measurements. 44th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/18-22/13; Page: 1752; LPI Contribution No. 1719
Hardgrove, C., Rice, M., Moersch, J., Mitrofanov, I., Litvak, M., Wellington, D., Behar, A., Bell, J., Boynton, W., DeFlores, L., Drake, D., Fedosov, F., Golovin, D., Jun, I., Harshman, K., Kozyrev, A., Malakhov, A., Milliken, R., Kuzmin, R., , Mischna, M., et al. (2013, Fall). DAN Active Parameters and Mastcam Hydration Survey Imaging: Comparisons Across Yellowknife Bay, Gale Crater, Mars. American Geophysical Union, Fall Meeting 2013.
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Abstract #P21D-07
Jun, I., Mischna, M., Tate, C., Behar, A., Boynton, W., DeFlores, L., Fedosov, F., Golovin, D., Gómez-Elvira, J., Hardgrove, C., Harshman, K., Kahanpää, H., Kozyrev, A., Kuzmin, R., Litvak, M., Malakhov, A., Moersch, J., Mokrousov, M., Nikiforov, S., , Sanin, A., et al. (2013, March). Neutron Background Environment Measured by the Mars Science Laboratory's (MSL) Dynamic Albedo of Neutrons (DAN) Instrument During the First 100 Sols. 44th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/18-22/13; Page: 1608; LPI Contribution No. 1719
Jun, I., Mitrofanov, I., litvak, M., Sanin, A., Behar, A., Boynton, W., DeFlores, L., Golovin, D., Hardgrove, C., Harshman, K., Kozyrev, A., Kuzmin, R., Malakhov, A., Mischna, M., Moersch, J., Mokrousov, M., Nikiforov, S., Shvetsov, V., Tate, C., , Vostrukhin, A., et al. (2013, Fall). Neutron Background Measurements by the the MSL Dynamic Albedo of Neutrons (DAN) Instrument during the First 360 sols of the Surface Operation at Mars. American Geophysical Union, Fall Meeting 2013.
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Abstract #P23C-1809
Kuzmin, R., Mitrofanov, I., Litvak, M., Sanin, A., Varenikov, A., Hardgrove, C., Tate, C., Behar, A., Boynton, W., DeFlores, L., Fedosov, F., Golovin, D., Jun, I., Harshman, K., Kozyrev, A., Malakhov, A., Mischna, M., Moersch, J., Mokrousov, M., , Nikidorov, S., et al. (2013, March). Searching for Correlation of the MSL DAN Active Measurement Results with Local Diversity of the Surface Micro-Morphology and Regolith Texture Along the Rover Curiosity Traverse. 44th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/18-22/13; Page: 1484; LPI Contribution No. 1719
Litvak, M., Mitrofanov, I., Behar, A., Boynton, W., DeFlores, L., Fedosov, F., Golovin, D., Hardgrove, C., Harshman, K., Jun, I., Kozyrev, A., Kuzmin, R., Lisov, D., Malakhov, A., Milliken, R., Mischna, M., Moersch, J., Mokrousov, M., Nikiforov, S., , Sanin, A., et al. (2013, March). Estimation of Natural Neutron Emission from the Surface of the Gale Crater from the Ground Data from DAN and the Orbital Data from HEND. 44th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/18-22/13; Page: 1864; LPI Contribution No. 1719
Litvak, M., Mitrofanov, I., Behar, A., Boynton, W., Deflores, L., Fedosov, F., Golovin, D., Hardgrove, C., Harshman, K., Jun, I., Kozyrev, A., Kuzmin, R., Lisov, D., Malakhov, A., Milliken, R., Mischna, M., Moersch, J., Mokrousov, M., Nikiforov, S., , Sanin, A., et al. (2013, September). The water bulk distribution along MSL Curiosity traverse measured by DAN instrument. European Planetary Science Congress 2013. London, UK.
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Dates: 09/08-13/13; id.EPSC2013-283
Litvak, M., Mitrofanov, I., Behar, A., Boynton, W., Fedosov, F., Golovin, D., Jun, I., Lisov, D., Malakhov, A., Milliken, R., Mischna, M., Moersch, J., Mokrousov, M., Nikiforov, S., Sanin, A., Tate, C., Varenikov, A., Vostrukhin, A., & Harshman, K. (2013, April). Estimation of water distribution at Gale crater based on the joint analysis of DAN/MSL and HEND/Odyssey data. EGU General Assembly 2013. Vienna, Austria.
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Dates: 04/07-12/13; id. EGU2013-7999
Livengood, T., Boynton, W., Sanin, A., Chin, G., Litvak, M., McClanahan, T., Mitrofanov, I., & Sagdeev, R. (2013, Fall). Exploration of Volatile Resources on the Moon with the Lunar Reconnaissance Orbiter (LRO) Lunar Exploration Neutron Detector (LEND). American Geophysical Union, Fall Meeting 2013.
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Abstract #P51B-1733
Livengood, T., Chin, G., Mitrofanov, I., Boynton, W., Sagdeev, R., Litvak, M., McClanahan, T., & Sanin, A. (2013, March). Hydrogen-Bearing Volatiles at the Lunar Terminator. 44th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/18-22/13; Page: 2946; LPI Contribution No. 1719
McClanahan, T., MItrofanov, I., Boynton, W., Chin, G., Starr, R., Evans, L., Sanin, A., Livengood, T., Sagdeev, R., & Milikh, G. (2013, March). Bulk Insolation Models as Predictors for Locations of High Lunar Hydrogen Concentration. 44th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/18-22/13; Page: 2374; LPI Contribution No. 1719
McClanahan, T., Mitrofanov, I., Boynton, W., Litvak, M., Chin, G., Sagdeev, R., Starr, R., Evans, L., Sanin, A., Livengood, T., & SU, J. (2013, Fall). Diurnal Effects on Lunar Slope Hydration derived from the Lunar Orbiting Neutron Spectrometers and Lunar Orbiting Laster Altimeter Topography. American Geophysical Union, Fall Meeting 2013.
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Abstract #P51B-1734
Mitrofanov, I., Boynton, W., Harshman, K., Kuzmin, R., Lisov, D., litvak, M., Sanin, A., & Starr, R. (2013, Fall). Water in the soil of the Gale crater on Mars: joint analysis of DAN/MSL and HEND/Mars Odyssey data. American Geophysical Union, Fall Meeting 2013.
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Abstract #P43D-03
Mitrofanov, I., Litvak, M., Lisov, D., Behar, A., Boynton, W., Deflores, L., Fedosov, F., Golovin, D., Hardgrove, C., Harshman, K., Jun, I., Kozyrev, A., Kuzmin, R., Malakhov, A., Mischna, M., Moersch, J., Mokrousov, M., Nikiforov, S., Sanin, A., , Shvetsov, V., et al. (2013, March). Content of Hydrogen at Testing Spots of the Gale Crater: The First Data from DAN Onboard the Curiosity Mars Rover. 44th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/18-22/13; Page: 1487; LPI Contribution No. 1719
Moersch, J., Hardgrove, C., Kah, L., Gupta, S., Tate, C., Litvak, M., Mitrofanov, I., Behar, A., Boynton, W., Deflores, L., Drake, D., Fedosov, F., Golovin, D., Jun, I., Harshman, K., Kozyrev, A., Malakhov, A., Milliken, R., Mischna, M., , Mokrousov, M., et al. (2013, March). Detection of Subsurface Vertical Geochemical Inhomogeneity with the MSL DAN Experiment: Modeling and Results from Bradbury Landing to Rocknest. 44th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/18-22/13; Page: 1852; LPI Contribution No. 1719
Moersch, J., Hardgrove, C., Tate, C., Litvak, M., Mitrofanov, I., Behar, A., Boynton, W., DeFlores, L., Fedosov, F., Harshman, K., Golovin, D., Jun, I., Kozyrev, A., Kuzmin, R., Lisov, D., Malakhov, A., Milliken, R., Mischna, M., Mokrousov, M., , Nikiforov, S., et al. (2013, Fall). Iterative modeling of hydrogen in multiple subsurface layers with MSL/DAN exit traverse data from Yellowknife Bay, Gale crater, Mars. American Geophysical Union, Fall Meeting 2013.
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Abstract #P14B-08
Sanin, A., Mitrofanov, I., Litvak, M., Boynton, W., Chin, G., Evans, L., Garvin, J., Golovin, D., Harshman, K., McClanahan, T., Malakhov, A., Mokrousov, M., Milikh, G., Sagdeev, R., & Starr, R. (2013, March). Estimation of the Hydrogen Concentration in Lunar South Polar Regions of Permafrost in Vicinity of Cabeus and Shoemaker Craters. 44th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/18-22/13; Page: 2741; LPI Contribution No. 1719
Sanin, A., Mitrofanov, I., Litvak, M., Boynton, W., Chin, G., Evans, L., Garvin, J., Golovin, D., Harshman, K., Mcclanahan, T., Malakhov, A., Milikh, G., Mokrousov, M., Sagdeev, R., & Starr, R. (2013, April). Estimation of the Hydrogen Abundance in the Cabeus and Shoemaker Craters. EGU General Assembly 2013. Vienna, Austria.
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Dates: 04/07-12/13; id. EGU2013-8381
Sanin, A., Mitrofanov, I., Litvak, M., Golovin, D., Boynton, W., Chin, G., Evans, L., Garvin, J., Harshman, K., Livengood, T., McClanahan, T., Milikh, G., Sagdeev, R., Starr, R., & Tretyakov, V. (2013, Fall). Four Years of the Lunar Hydrogen Exploration by the LEND experiment on-board the LRO mission. American Geophysical Union, Fall Meeting 2013.
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Abstract #P43D-04
Tate, C., Moersch, J., Jun, I., Hardgrove, C., Michna, M., Litvak, M., Varenikov, A., Mitrofanov, I., Behar, A., Boynton, W., Deflores, L., Fedosov, F., Golovin, D., Harshman, K., Kozyrev, A., Malakhov, A., Milliken, R., Mokrousov, M., Nikiforov, S., , Sanin, A., et al. (2013, March). Diurnal Variations in MSL DAN Passive Measurements with Atmospheric Pressure and Soil Temperature. 44th Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/18-22/13; Page: 1601; LPI Contribution No. 1719
litvak, M., Mitrofanov, I., Behar, A., Boynton, W., DeFlores, L., Fedosov, F., Golovin, D., Hardgrove, C., Harshman, K., Kozyrev, A., Jun, I., Kuzmin, R., Lisov, D., Malakhov, A., Milliken, R., Mischna, M., Moersch, J., Mokrousov, M., Nikiforov, S., , Sanin, A., et al. (2013, Fall). Local variations of bulk hydrogen and chlorine content measured at the contact between the Sheepbed and Gillespie Lake units in Yellowknife Bay, Gale Crater, using the DAN instrument onboard Curiosity. American Geophysical Union, Fall Meeting 2013.
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Abstract #P14B-07
Archer, P., Lauer, H., Sutter, B., Ming, D., Niles, P., & Boynton, W. (2012, March). A Possible Organic Contribution to the Low Temperature CO_2 Release seen in Mars Phoenix Thermal and Evolved Gas Analyzer Data. 43rd Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/19-23/12; LPI Contribution No. 1659; id.2276
Boynton, W., Droege, G., Harshman, K., Schaffner, M., Mitrofanov, I., & McClanahan, T. (2012, September). Constraints on Hydrogen Mobility provided by High Spatial Resolution Studies of Epithermal Neutron Emission from the Lunar Poles. European Planetary Science Congress 2012. Madrid, Spain.
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Dates: 09/23-28/12; id. EPSC2012-872
Boynton, W., Droege, G., Harshman, K., Schaffner, M., Mitrofanov, I., McClanahan, T., & Team, L. (2012, March). Constraints on Lunar Hydrogen Mobility Provided by High Spatial Resolution Studies of Epithermal Neutron Emission. 43rd Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/19-23/12; LPI Contribution No. 1659; id.2244
Boynton, W., Droege, G., Harshman, K., Schaffner, M., Mitrofanov, I., McClanahan, T., & Team, L. (2012, October). Latitudinal Enrichment of Hydrogen in the Lunar Polar Regions: Constraints on Hydrogen Mobility. Annual Meeting of the Lunar Exploration Analysis Group. Greenbelt, MD.
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Dates: 10/22-24/12; LPI Contribution No. 1685; id.3029
Boynton, W., Lauretta, D., Beshore, E., Barnouin, O., Bierhaus, E., Binzel, R., Christensen, P., Daly, M., Grindlay, J., Hamilton, V., Hildebrand, A., Mehall, G., Reuter, D., Rizk, B., Simon-Miller, A., & Smith, P. (2012, September). The OSIRIS-REx mission to RQ36: nature of the remote sensing observations. European Planetary Science Congress 2012. Madrid, Spain.
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Dates: 09/23-28/12; id. EPSC2012-875
Cannon, K., Sutter, B., Ming, D., Boynton, W., & Quinn, R. (2012, March). Possible Calcite and Magnesium Perchlorate Interaction in the Mars Phoenix Thermal and Evolved Gas Analyzer (TEGA). 43rd Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/19-23/12; LPI Contribution No. 1659; id.2008
Karunatillake, S., Gasnault, O., McLennan, S., Rogers, A., Wray, J., Squyres, S., & Boynton, W. (2012, March). The Hydration State of Sulfates on Mars. 43rd Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/19-23/12; LPI Contribution No. 1659; id.2940
Kim, K., Amano, Y., Boynton, W., Klingelhöfer, G., Brückner, J., Hamara, D., Starr, R., Lim, L., Hasebe, N., Ju, G., Fagan, T., Ohta, T., & Shibamura, E. (2012, March). Introduction to the Scientific Investigation of an Active X-Ray Spectrometer for the SELENE-2 Rover. 43rd Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/19-23/12; LPI Contribution No. 1659; id.1282
Kim, K., Amano, Y., Boynton, W., Klingelhöfer, G., Brückner, J., Hasebe, N., Hamara, D., Starr, R., Lim, L., Ju, G., Fagan, T., Ohta, T., & Shibamura, E. (2012, October). An Active X-Ray Spectrometer Proposed for the SELENE-2 Rover. International Workshop on Instrumentation for Planetary Missions. Greenbelt, MD.
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Dates: 10/10-12/12; LPI Contribution No. 1683; id.1078
Litvak, M., Mitrofanov, I., Sanin, A., Boynton, W., Chin, G., Evans, L., Harshman, K., Droege, G., Malakhov, A., Milikh, G., McClanahan, T., Sagdeev, R., & Starr, R. (2012, March). Global Maps of the Moon Neutron Flux from LEND Instrument Onboard LRO. 43rd Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/19-23/12; LPI Contribution No. 1659; id.2101
Litvak, M., Mitrofanov, I., Sanin, A., Boynton, W., Harshman, K., Droege, J., Malakhov, A., Golovin, D., Starr, R., & Evans, L. (2012, April). Global mapping of lunar neutron flux by LEND/LRO. EGU General Assembly 2012. Vienna, Austria.
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Dates: 04/22-27/12; Page: 7113
Livengood, T., Chin, G., Mitrofanov, I., Boynton, W., Sagdeev, R., Litvak, M., McClanahan, T., & Sanin, A. (2012, Fall). Hydrogen-Bearing Volatiles at the Lunar Equatorial Terminator. American Geophysical Union, Fall Meeting 2012.
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Abstract #P51C-03
Livengood, T., Chin, G., Mitrofanov, I., Boynton, W., Sagdeev, R., Litvak, M., McClanahan, T., & Sanin, A. (2012, October). Hydrogen-Bearing Volatiles at the Lunar Equatorial Terminator. Annual Meeting of the Lunar Exploration Analysis Group. Greenbelt, MD.
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Dates: 10/22-24/12; LPI Contribution No. 1685; id.3040
Livengood, T., Mitrofanov, I., Boynton, W., Chin, G., McClanahan, T., Starr, R., Evans, L., & Team, L. (2012, March). A Search for Hydrogen near the Lunar Terminator at Low Latitude. 43rd Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/19-23/12; LPI Contribution No. 1659; id.2643
McClanahan, T., Mitrofanov, I., Boynton, W., Chin, G., Droege, G., Evans, L., Garvin, J., Harshman, K., Litvak, M., Malakhov, A., Livengood, T., Milikh, G., Nandikotkur, G., Neumann, G., Smith, D., Sagdeev, R., Sanin, A., Starr, R., Trombka, J., & Zuber, M. (2012, March). Correlated Observations of Epithermal Neutrons and Polar Illumination Models from Orbital Neutron Detectors. 43rd Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/19-23/12; LPI Contribution No. 1659; id.2341
McClanahan, T., Mitrofanov, I., Boynton, W., Chin, G., Livengood, T., Starr, R., Evans, L., Neumann, G., Mazarico, E., Smith, D., Team, L., & Team, L. (2012, March). Estimation of Orbital Neutron Detector Spatial Resolution by Systematic Shifting of Differential Topographic Masks. 43rd Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/19-23/12; LPI Contribution No. 1659; id.2302
McClanahan, T., Mitrofanov, I., Boynton, W., Litvak, M., Milikh, G., Evans, L., Starr, R., Livengood, T., Chin, G., Harshman, K., & Droege, G. (2012, Fall). Insolation Effects on the Lunar Hydrogen Budget: Correlated Observations of the Lunar Reconnaissance Orbiter's LEND, LOLA and Diviner Instruments. American Geophysical Union, Fall Meeting 2012.
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Abstract #P43B-1921
Meslin, P., Hamara, D., Boynton, W., Sabroux, J., & Gasnault, O. (2012, March). Analysis of Uranium and Thorium Lines in Mars Odyssey Gamma Spectra and Refined Mapping of Atmospheric Radon. 43rd Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/19-23/12; LPI Contribution No. 1659; id.2852
Mitrofanov, I., Sanin, A., Litvak, M., Boynton, W., Chin, G., Evans, L., Garvin, J., Harshman, K., McClanahan, T., Milikh, G., Sagdeev, R., & Starr, R. (2012, Fall). Water Ice Permafrost at Lunar Poles: Observational Evidence from Lend Instrument Onboard Lro. American Geophysical Union, Fall Meeting 2012.
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Abstract #P43B-1920
Sanin, A., Mitrofanov, I., Litvak, M., Boynton, W., Chin, G., Droege, G., Evans, L., Garvin, J., Golovin, D., Harshman, K., McClanahan, T., Malakhov, A., Mokrousov, M., Milikh, G., Sagdeev, R., & Starr, R. (2012, March). Testing of Lunar Permanently Shadowed Regions for Water Ice. 43rd Lunar and Planetary Science Conference. The Woodlands, TX.
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Dates: 03/19-23/12; LPI Contribution No. 1659; id.2134
Sanin, A., Mitrofanov, I., Litvak, M., Boynton, W., Chin, G., Evans, L., Garvin, J., Golovin, D., Harshman, K., McClanahan, T., Malakhov, A., Milikh, G., Sagdeev, R., & Starr, R. (2012, Fall). Testing of Lunar Permanently Shadowed Regions for Water Ice: LEND Results for about Three Years of Observations. American Geophysical Union, Fall Meeting 2012.
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Abstract #P43B-1918
Sanin, A., Mitrofanov, I., Litvak, M., Boynton, W., Evans, L., Harshman, K., Malakhov, A., & Starr, R. (2012, April). Testing Lunar Permanently Shadowed Regions for Water Ice: LEND Results from LRO. EGU General Assembly 2012. Vienna, Austria.
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Dates: 04/22-27/12; Page: 8062
Sanin, A., Mitrofanov, I., Litvak, M., Malakhov, A., Boynton, W., Chin, G., Droege, G., Evans, L., Garvin, J., Golovin, D., Harshman, K., McClanahan, T., Milikh, G., Mokrousov, M., Sagdeev, R., & Starr, R. (2012, October). Searching for Water Ice Permafrost: LEND Results for About Three Years of Observations. Annual Meeting of the Lunar Exploration Analysis Group. Greenbelt, MD.
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Dates: 10/22-24/12; LPI Contribution No. 1685; id.3020

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Boynton, W. V., Pal'Shin, V., & et, a. l. (2013, Fall). IPN localizations of Konus short GRBs (Pal'shin+, 2013). VizieR On-line Data Catalog: J/ApJS/207/38.
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Originally published in: 2013ApJS..207...38P
Hurley, K., Pal'Shin, V., Aptekar, R., Golenetskii, S., Frederiks, D., Mazets, E., Svinkin, D., Briggs, M., Connaughton, V., Meegan, C., Goldsten, J., Boynton, W., Fellows, C., Harshman, K., Mitrofanov, I., Golovin, D. V., Kozyrev, A., Litvak, M., Sanin, A., , Rau, A., et al. (2013, Fall). IPN supplement to the Fermi GBM (Hurley+, 2013). VizieR On-line Data Catalog: J/ApJS/207/39.
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Originally published in: 2013ApJS..207...39H
Hurley, K., Atteia, J., Barraud, C., Pelangeon, A., Boer, M., Vanderspek, R., Ricker, G., Mazets, E., Golenetskii, S., Frederiks, D., Pal'Shin, V., Aptekar, R., Smith, D., Wigger, C., Hajdas, W., Rau, A., von, K. A., Mitrofanov, I., Golovin, D., , Kozyrev, A., et al. (2012, Fall). The IPN supplement to the HETE-2 GRB catalog (Hurley+, 2011). VizieR On-line Data Catalog: J/ApJS/197/34.
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Originally published in: 2011ApJS..197...34H

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William V Boynton

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William V Boynton

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