Eric C Pearce

Interests

Research

Space Situational Awareness in Cislunar SpacePhotometric characterization of man made satellitesSpace surveillance systemsHigh speed photometryRapid time domain observational astronomy

Courses

Scholarly Contributions

Journals/Publications

• Krantz, H., Pearce, E. C., & Block, A. (2021). Characterizing the All-Sky Brightness of Satellite Mega-Constellations and the Impact on Astronomy Research. Proceedings of the AMOS Conference.
• Pearce, E. C., Weiner, B., & Krantz, H. (2020). Examining the effects of on-orbit aging of SL-12 rocket bodies using visible band spectra with the MMT telescope. Journal of space safety engineering, 7(3), 376-380.

Proceedings Publications

• Pearce, E. C., Krantz, H. R., Kirshner, M., & Sease, B. (2021, September). apid Discrimination of Resident Space Objects Using Near-Infrared Photometry. In Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference.
  More info

  The characterization of deep space debris poses a significant challenge in Space Situational Awareness (SSA). To be most useful, characterization should provide actionable information quickly, even under non-ideal observing conditions. Multi-color photometry and the resultant color indices offer the potential to rapidly discriminate between debris and intact space objects such as rocket bodies and satellites. These multi-color techniques can also identify anomalous members of object groups and cue higher fidelity data collections and studies. In this paper, we present the results from our 2020–2021 measurements campaign supplemented by further analysis from our previous 2016–2017 campaign. In 2017-2018, our team began developing and demonstrating rapid multi-color photometry techniques using the Russian SL-12 fourth stage rocket bodies (RB). We demonstrated that anomalous members of our rocket body cohort can be readily identified using only near-infrared (IR) color indices. During late 2020 and early 2021, our team expanded our previous characterization by using both the United Kingdom Infrared Telescope (UKIRT) Wide Field Camera (WFCAM) and the 1–5 m Imager-Spectrometer (UIST). Specifically, we have expanded our data set to include:(a) more SL-12 fourth stage RBs increasing years-on-orbit sampling from our 2016-2017 campaign, (b) Centaur RBs of the same type as the returning RB cataloged as Near-Earth Object 2020 SO, (c) a selection of Molniya communication satellites including the -1K, 1T, -2, and -3 variants, (d) Russian FREGAT and SL-6 upper stage RBs in Molniya orbits, (e) intact payloads selected from satellites using the Boeing HS-376 busses. Our new data set provides us with overlapping broadband IR colors and high-resolution spectra in those same color bands. We carefully chose our targets to include a mix of objects with known compositions to allow the development and evaluation of novel techniques to interpret our broadband near-IR photometry. The addition of Molniya payloads and RBs is a unique addition to existing literature since all previously published studies have focused on objects in geosynchronous orbits. For the first time, we can analyze near-IR photometry with the context of the full resolution near-IR spectra of same-type. We offer insight into refining the spectral bands of interest for characterization and provide an approach to improve rapid discrimination capabilities using substantially more efficient near-IR photometric techniques.
• Pearce, E. C., Sease, B., & Hennessy, G. (2019, September). Multi-band characterization of aging effects of space debris in the visible and near IR with UKIRT and the MMT. In Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference.
  More info

  The utility of photometric and spectroscopic measurements in the near-IR has been demonstrated by several researchers to have utility for the characterization and identification of spacecraft materials. To be most effective, characterization must be performed quickly and under non-ideal operational conditions, generally using non-resolved techniques. This researcher has used near-IR photometry to develop techniques to rapidly discriminate between different classes of space objects, and to identify anomalous members of specific groups of objects. Prior measurements have identified an anomalous SL-12 rocket body which was identified from a larger class of similar objects based on it near IR colors. In this study we combine the previous UKIRT near-IR five-color photometric measurements with newly acquired measurements with the UKIRT WFCAM over a wider range of phase angles and geometries. The additional measurements and analysis allow correction of the color indices for solar phase angle and allow determination of the inherent color variations characteristic of physical differences between the objects. In addition to the UKIRT measurements, we supplement the analysis data with Sloan r’, i’, and z’ high speed photometric data with the Chimera High-Speed photometer on the Kuiper 61” telescope at Mt. Lemmon, and high resolution spectroscopy taken with the 6.5 m MMT telescope with the Blue Channel Spectrograph on a subset of the objects.
• Pearce, E. C., Weiner, B. J., Krantz, H. R., Block, A., Rockowitz, K., Wilson, M., Sease, B., & Hennessy, G. (2019, september). Examining the Effects of On-Orbit Aging of SL-12 Rocket Bodies using Visible Band Spectra with the MMT Telescope. In Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference.
  More info

  The characterization of deep space debris has posed a significant challenge in SSA. To be most operationally effective, characterization must be performed quickly and under non-ideal operational conditions, generally using non-resolved techniques. The use of multi-color photometry and the resultant color indices offer the potential to rapidly discriminate between debris and intact space objects such as rocket bodies and satellites. However, these studies are not well informed by high resolution spectra of these same objects due to the lack of prior measurements with large astronomical telescopes. High resolution spectroscopy is not routinely collected by our SSA network. Nonetheless, several researchers have collected satellite spectra for research purposes. Several researchers have also noted the progressive reddening of spacecraft surfaces. Jorgensen measured reflectance spectra over a range of years on orbit (YOO) of 10-13 years of foreign discarded rocket bodies and noted significant increase in relative reflectance above 750 nm. Similarly, aging has been noted on GPS payloads using BVRI photometry by Fliegel.In this study, we have collected high resolution spectra of a group of five Russian SL-12 rocket bodies in geosynchronous orbit. The spectra were collected with the Blue Channel Spectrograph on the 6.5 m MMT telescope at Mt. Hopkins. The measurements were taken using the 300-line grating, which is blazed for the red, and can cover a 5200 Å range at dispersion 1.96 Å/pixel. The large collecting aperture of the MMT allowed the rapid collection of multiple high signal-to-noise spectra with only 2 minutes per exposure. This short exposure allowed us to have confidence the solar phase angle was near constant during each collection, but that the spectra were averaged over the rotation of the rocket body. These spectra allow analysis of both the variation in albedo over a large wavelength range, and searches for discrete absorption features. The SL-12 (also called the “Proton K”) was a mainstay Russian four-stage to GEO launch vehicle that was used from 1974 to 2012 (Gunter 2017). The SL-12 fourth stage rocket bodies (henceforth referred to as “SL-12 RB”) offer a convenient ensemble of objects for which photometric techniques can be developed and tested. For this study, five SL-12s with a range of years-on-orbit (YOO) ranging from 23-35 years were collected, allowing a comparative study of the evolution of the spectra over a 12-year difference in age. Additionally, all these objects have been previously observed with the UKIRT WFCAM. The spectra are analyzed for evidence of the effects of on-orbit reddening and other changes over time.
• Pearce, E., Weiner, B. J., & Krantz, H. (2019). Examining the effects of on-orbit aging of SL-12 rocket bodies using visible band Spectra with the MMT Telescope.
• Block, A., Schildknecht, T., Reddy Kanupuru, V. V., Ford, H. A., & Pearce, E. C. (2017, September). Rapid Characterization of Geosynchronous Space Debris with 5-color Near-IR Photometry. In Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference 2017.
  More info

  The characterization of deep space debris has posed a significant challenge in SSA. To be most operationally effective, characterization must be performed quickly and under non-ideal operational conditions, generally using non-imaging techniques. The use of multi-color photometry and the resultant color indices in the near and short wave IR offer the potential to rapidly discriminate between debris and intact space objects such as rocket bodies and satellites. Specifically, the color indices surrounding the near IR Z band (0.83-0.925 µm) show promise to differentiate materials while providing a more efficient data collection when compared to spectroscopic techniques. Similar techniques have been demonstrated in the astronomical community to discriminate between different classes of near Earth asteroids. The diagnostic attributes of the Z band are particularly compelling as similar diagnostic color indices can be measured using visible telescopes and the corresponding Sloan z’ band. Initial results of an extensive survey of cataloged debris, high area-to-mass ratio (HAMR) debris, rocket bodies, and intact satellites with the UKIRT WFCAM are presented to assess the efficacy of these techniques.
• Pearce, E. C., Avner, L., Block, A., Krantz, H., & Rockowitz, K. (2018, September). Pomenis: A Small Portable Astrograph for SSA. In Advanced Maui Optical and Space Surveillance Technologies Conference (AMOS).
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  The Steward Observatory SSA team developed the Pomenis Astrograph System to be a dedicated telescope, which will produce a steady stream of SSA data. The astrograph is innovative with its fast optical design versus a traditional longer focal length found on commercial Cassegrain telescope that most “Raven class” systems are based on. Compared with other systems used for SSA, the Pomenis astrograph has an exceptionally wide 5-degree field of view and a fast readout CCD camera, thus enabling synoptic survey of the deep space satellite population several times per night. The aperture and focal length were carefully selected to achieve sensitivity relevant to synoptic GEO SSA with an integration time short enough to allow high precision astrometric reference using the streaked background stars. With its 7-color filter wheel, Pomenis also performs multi-color photometric screening of deep space satellites looking for anomalous behavior and can identify objects for higher fidelity measurements and study. Pomenis is housed in a unique trailer mounted enclosure, which enables the system to be deployed with minimal infrastructure, operated remotely and autonomously, and easily relocated as required. In addition to the SSA measurements described above, the astrograph will be taking full-hemisphere night sky brightness (NSB) measurements in multiple color bands. These measurements will be compared to previously conducted each decade on Mt. Hopkins and Kitt Peak to study the increase in light pollution in southern Arizona. Pomenis will allow these measurements to be made on a more routine basis, and over a tighter spatial grid. This will facilitate our monitoring of the light pollution environment at the University’s observatory sites and assess the impact of future development on the quality of the night sky. Additionally, Pomenis will be used for serendipitous astronomical surveys and to develop new techniques for precise photometric reduction over a wide field of view and high air mass.
• Pearce, E. C., Avner, L., Krantz, H., & Rockowitz, K. (2018, September). Chimera: First SSA results of a new high-speed, three-color photometer for space surveillance and astronomy. In Advanced Maui Optical and Space Surveillance Technologies Conference.
  More info

  Chimera is a high-speed photometer with capabilities of three-color photometry simultaneously in the Sloan r’ (562-695 nm), i’ (695-844 nm), and z’ (826-920 nm) bands. The optical design includes three reimagers and two diachroic beam splitters which provide field of views of 9.7 arcmininutes in the z’ band and 6.0 arcminutes in the r’ and I’ bands. The large field of view allows for many photometric calibration methods. Chimera utilizes three Princeton Instruments Pro-EM CCD cameras. These electron multipliers have data rates up to 228 Hz in full-frame mode and data rates over 1000 Hz are possible by using regions of interest and binning the frame. Chimera is currently designed for the Steward Observatory Kuiper 1.54 m Telescope with discussion of expanding to other telescopes. Characterization of rapidly-rotating satellites and space debris require high-speed multicolor photometers. For man-made satellites and space debris, photometric measurements are made from the reflections off of flat surfaces of the target. These reflections are on the time scale as short as a few milliseconds. The high frame rate of Chimera allows detailed study of these reflections and the large field of view allows calibrated photometric measurements in all color bands. Having data at the same time in three color bands provides information on the composition, the fluctuation in brightness, and rotational properties of the satellite. Although designed to observe man-made satellites and space debris, Chimera’s high-speed multicolor capabilities can be used for astroseismology, transiting exoplanets, high-energy phenomena, and near-Earth asteroids. An image analysis GUI allows users to process the data near real-time with basic astronomical reduction, provide instrumental and relative lightcurves of the selected moving or stationary target, and perform various period analysis techniques. Calibrated results and astrometry are measured from a separate, offsite software package, a highly-modified PHOTOMETRY PIPELINE (PP), originally developed by Michael Mommert for near-Earth asteroid calibrated photometry. PP can use multiple astrometric and photometric catalogs and can be used for most data with similar field of views as Chimera. Here we present the optical and opto-mechanical design of Chimera, instrument characterization, the first science results from Chimera, a near real-time analysis software package, the modified PP, and the future applications of Chimera.
• Block, A., Block, A., Block, A., Schildknecht, T., Schildknecht, T., Schildknecht, T., Reddy Kanupuru, V. V., Reddy Kanupuru, V. V., Reddy Kanupuru, V. V., Ford, H. A., Ford, H. A., Ford, H. A., Pearce, E. C., Pearce, E. C., & Pearce, E. C. (2017, September). Rapid Characterization of Geosynchronous Space Debris with 5-color Near-IR Photometry. In Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference 2017.
  More info

  The characterization of deep space debris has posed a significant challenge in SSA. To be most operationally effective, characterization must be performed quickly and under non-ideal operational conditions, generally using non-imaging techniques. The use of multi-color photometry and the resultant color indices in the near and short wave IR offer the potential to rapidly discriminate between debris and intact space objects such as rocket bodies and satellites. Specifically, the color indices surrounding the near IR Z band (0.83-0.925 µm) show promise to differentiate materials while providing a more efficient data collection when compared to spectroscopic techniques. Similar techniques have been demonstrated in the astronomical community to discriminate between different classes of near Earth asteroids. The diagnostic attributes of the Z band are particularly compelling as similar diagnostic color indices can be measured using visible telescopes and the corresponding Sloan z’ band. Initial results of an extensive survey of cataloged debris, high area-to-mass ratio (HAMR) debris, rocket bodies, and intact satellites with the UKIRT WFCAM are presented to assess the efficacy of these techniques.
• Pearce, E., Ford, H., Schildknecht, T., Reddy, V., Block, A., & Rockowitz, K. (2017). "Rapid Characterization of Geosynchronous Space Debris with 5-color Near-IR Photometry". In Advanced Maui Optical and Space Surveillance (AMOS) Technologies Conference.

Presentations

• Pearce, E. C. (2020, March). Reinventing Space Situational Awareness in Cislunar Space. AME Seminar/AZ Space Business Roundtable. University of Arizona AME: AME.
  More info

  Our current space situational awareness (SSA) capabilities have evolved and matured since originally being developed in the mid-1950s in response to the imminent launch of the first Rus-sian satellite Sputnik. The development of our ground-based space surveillance systems and techniques were led by a coalition of academic and Government organizations to meet the emerg-ing needs to detect, track, and catalog objects in Earth orbit. Very early in the development of our space surveillance network, the complementary capabilities of optical and radar systems were embraced as a foundational element of our space surveillance network (SSN).Today science, civil, commercial, and military interests are motivating a return to Moon and the unique orbital regime surrounding the Moon and the Earth/Moon Lagrange points. China al-ready has an extensive lunar exploration program, with a lander and rover on the far side of the Moon and a communication relay satellite stationed in an L2 halo orbit. NASA plans to exploit the unique astrodynamics at L1 as a lunar and interplanetary gateway and return man to the Moon by 2024. Commercial interests see a future of providing services and mining product from the lunar polar regions. In time, robust Earth/Moon communication relay and lunar-GPS constel-lations will be deployed. Inevitably cislunar space will become congested, contested, and con-tested. To ensure safety and freedom to operate in this new domain, space-faring nations must es-tablish foundational surveillance, cataloging, characterization, and space traffic control capabili-ties. While our nation’s capabilities to maintain awareness in the confines of the traditional orbits out to the geosynchronous belt is mature, we have essentially no capabilities even to detect ob-jects in the cislunar environment. Many of the same characteristics of cislunar space that enable these missions are the same characteristics that make cislunar space a challenge for SSA. The large distance to cislunar satellites compared to circumterrestrial satellites, and difficult viewing geometries make surveillance and detection of cislunar satellites much more difficult. Equally important, the astrodynamic attributes that allow low-energy transfers in cislunar space and are enabling to the diverse missions proposed are the same attributes that make establishing and maintaining a catalog in cislunar space difficult. These problems are multi-disciplinary problems and offer a new opportunity for the combined talents of academia, our different Colleges, and Government organizations to reinvent SSA in this challenging new domain.
• Pearce, E. C., Krantz, H. R., Kirshner, M., & Lock, A. (2020, February). Night Sky Brightness and Ground-Based Cislunar SSA. AFRL First Annual Cislunar Working Group. Albuquerque NM: AFRL.
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  Presentation over viewing the teams work on night sky modeling and measurements at low lunar elongations in the context of cislunar SSA. Measurement and modeling techniques, and observational difficulties of these measurements were reviewed.
• Pearce, E. C., Krantz, H. R., Kirshner, M., Block, A., & Sease, B. (2020, September). Multicolor and Spectral Characterization of Space Objects in the Near-IR. Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference. Maui HI: AFRL (Maui Economic Development Board).
  More info

  The characterization of deep space debris has posed a significant challenge in SSA. In order to be most useful, characterization should be performed quickly and under non-ideal observational conditions, generally using non-resolved techniques. The use of multi-color photometry and the resultant color indices offer the potential to rapidly discriminate between debris and intact space objects such as rocket bodies and satellites. However, these studies are not well informed by high resolution spectra of these same objects due to the lack of prior measurements with large astronomical telescopes. During early 2020, our team measured an ensemble of rocket-bodies, intact spacecraft, and cataloged debris with both the UKIRT WFCAM (5-color near-IR photometry), and with the UKIRT 1-5 m Imager-Spectrometer (UIST). This data set provides us with overlapping broadband IR colors, and high resolution spectra in the same color bands. Combined with previous measurements with WFCAM in 2016-2017, and high resolution visible band spectra with the MMT telescope, this is a unique data set. Our targets were carefully chosen to include a mix of objects with known compositions that would allow the development and evaluation of techniques to interpret our broadband near-IR photometry while being informed with the higher resolution spectra from UIST. The rocket bodies selected for study included the SL-12 fourth stage rocket bodies (SL-12 RB) measured in our previous 5-color survey. The intact payloads selected were chosen from satellites using the Boeing HS-376 busses. These objects are dominated the solar panels which completely cover the spacecraft. Four different generations of solar panel were used over the twenty years of satellite development, with the earliest HS-376 busses using shallow function n/p silicon cells, and later models using GaAs/Ge single junction and GaInP2/GaAs/Ge dual junction panels. Both the SL-12 RB and Boeing HS-376 serve as ideal test objects of known composition for controlled studies.In this paper, our team presents an analysis of our 2020 observing campaign, supplemented by our previous measurements with WFCAM and the MMT telescope. We evaluate the efficacy of using near-IR color-indices to discriminate space debris and other objects from small solar-panel covered satellites. We also refine previous techniques to measure near-IR colors with WFCAM with a more efficient observing protocol. Finally, this data set has allowed us to more densely sample photometric and spectral observations over the entire range of available phase angle during a single collect and to adjust our interpretation of near-IR color indices in that context.
• Block, A., Schildknecht, T., Reddy Kanupuru, V. V., Ford, H. A., Pearce, E. C., Block, A., Schildknecht, T., Reddy Kanupuru, V. V., Ford, H. A., Pearce, E. C., Block, A., Schildknecht, T., Reddy Kanupuru, V. V., Ford, H. A., & Pearce, E. C. (2017, September). Rapid Characterization of Geosynchronous Space Debris with 5-color Near-IR Photometry. Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference 2017.
  More info

  The characterization of deep space debris has posed a significant challenge in SSA. To be most operationally effective, characterization must be performed quickly and under non-ideal operational conditions, generally using non-imaging techniques. The use of multi-color photometry and the resultant color indices in the near and short wave IR offer the potential to rapidly discriminate between debris and intact space objects such as rocket bodies and satellites. Specifically, the color indices surrounding the near IR Z band (0.83-0.925 µm) show promise to differentiate materials while providing a more efficient data collection when compared to spectroscopic techniques. Similar techniques have been demonstrated in the astronomical community to discriminate between different classes of near Earth asteroids. The diagnostic attributes of the Z band are particularly compelling as similar diagnostic color indices can be measured using visible telescopes and the corresponding Sloan z’ band. Initial results of an extensive survey of cataloged debris, high area-to-mass ratio (HAMR) debris, rocket bodies, and intact satellites with the UKIRT WFCAM are presented to assess the efficacy of these techniques.
• Pearce, E. C. (2017, 2017-03-17). Astronomy Tracks Sputnik and Beyond: How Applied Astronomy has Met the Challenges of the Space Age. Steward Observatory Public Lecture Series. Steward Observatory: Steward Observatory.
• Pearce, E. C. (2017, August). Rapid Characterization of Geosynchronous Space Debris with 5-color Near-IR Photometry. MIT Lincoln Laboratory Division Seminar. Lexington MA: MIT Lincoln Laboratory.
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  Invited Division Seminar in the Aerospace Division of the MIT Lincoln Laboratory.The characterization of deep space debris has posed a significant challenge in SSA. To be most operationally effective, characterization must be performed quickly and under non-ideal operational conditions, generally using non-imaging techniques. The use of multi-color photometry and the resultant color indices in the near and short-wave IR offer the potential to rapidly discriminate between debris and intact space objects such as rocket bodies and satellites. Specifically, the color indices surrounding the near IR Z band (0.83-0.925 µm) show promise to differentiate materials while providing a more efficient data collection when compared to spectroscopic techniques. Similar techniques have been demonstrated in the astronomical community to discriminate between different classes of near Earth asteroids. The diagnostic attributes of the Z band are particularly compelling as similar diagnostic color indices can be measured using visible telescopes and the corresponding Sloan z’ band. Initial results of an extensive survey of cataloged debris, high area-to-mass ratio (HAMR) debris, rocket bodies, and intact satellites with the UK IR Telescope (UKIRT) Wide Field Camera (WFCAM) are presented to assess the efficacy of these techniques. As a test case, an ensemble of Russian SL-12 rocket bodies (SL-12 RB) discarded at in geosynchronous orbit has been studied. One of these rocket bodies (2012-012D, SCN 38104) has been identified using these techniques to have anomalous near-IR spectral characteristics compared all others in the study. Additionally, this object and experiences unusual secular variations in its post-mission orbital elements.This work is being performed as part of a broader research initiative by the University of Arizona in Space Situational Awareness (UA SSA). Steward Observatory research is focusing on establishing a robust suite of programs for non-imaging characterization of satellites using small synoptic astrograph for initial screening, a SSA specific high-speed multi-color photometer, and supporting near-IR measurements from UKIRT and other telescopes. As part of this presentation, a brief overview of the overall effort will also be presented.
• Pearce, E. C., & Ford, H. A. (2017, 2017-04-12). Rapid Photometric Classification and Characterization of Space Objects. Non-Imaging Space Object Identification (NISOI) Workshop 2017. University of Arizona/LPL: Air Force Research Laboratory.
  More info

  An overview of my Steward Observatory satellite photometry program is presented along with preliminary results from the UKIRT near IR survey. Initial results focus on rapid discrimination of SL-12 rocket bodies with 5-color near-IR spectrophotometry.The NISOI Workshops are a series of working level meetings organized by AFRL/DE and help twice a year. Participation in the workshop is by invitation only and the presentation and discussion of preliminary results and in process work is strongly encouraged. This year is the first year that a University is hosting the Workshop on behalf of AFRL.
• Pearce, E. C., Jah, M. K., Hart, M., & Reddy Kanupuru, V. V. (2017, 01/26/2017). The Role of Universitiesin Space Situational Awareness and Global Space Traffic Management. Briefing to the US Senate and House Armed Services Committees Staff. Washington DC.

Poster Presentations

• Kingley, J., Angel, R., Davidson, W., Neff, D., Teran, J., Assenmacher, W., Peyton, K., Martin, H., Oh, C. J., Kim, D. W., Pearce, E. C., Rascon, M., Connors, T., Alfred, D., Jannuzi, B. T., Christensen, E., & Males, J. R. (2018, June). An inexpensive turnkey 6.5-m observatory with customizing options. Ground-based and Airborne Telescopes VII, part of SPIE Astronomical Telescopes + Instrumentation. Austin TX: SPIE.
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  A turnkey 6.5-m observatory has been developed for broad science applications with predefined performance specifications that can be verified on sky. This observatory can be delivered within five years at a fixed price. By combining academia and industrial partners with extensive experience and enormous investments in infrastructure it is possible to produce a highly valued optimized observatory with cost and schedule certainty. The challenge for scientists now becomes developing the science and instruments and not the observatory.
• Males, J. R., Christensen, E., Jannuzi, B. T., Alfred, D., Connors, T., Rascon, M., Pearce, E. C., Kim, D. W., Oh, C. J., Martin, H., Peyton, K., Assenmacher, W., Teran, J., Neff, D., Davidson, W., Angel, R., & Kingley, J. (2018, June). An inexpensive turnkey 6.5-m observatory with customizing options. Ground-based and Airborne Telescopes VII, part of SPIE Astronomical Telescopes + Instrumentation. Austin TX: SPIE.
  More info

  A turnkey 6.5-m observatory has been developed for broad science applications with predefined performance specifications that can be verified on sky. This observatory can be delivered within five years at a fixed price. By combining academia and industrial partners with extensive experience and enormous investments in infrastructure it is possible to produce a highly valued optimized observatory with cost and schedule certainty. The challenge for scientists now becomes developing the science and instruments and not the observatory.
• Pearce, E. C., Krantz, H., Avner, L., Durney, O., & Sauve, C. (2018, June). Chimera: A high-speed three-color photometer for space surveillance and astronomy. SPIE Astronomical Telescopes + Instrumentation. Austin TX: SPIE.
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  High-speed optical photometers have been used for decades to characterize man-made satellites and space debris in Earth orbit. In the 1970s and 1980s, these instruments were typically based on photomultiplier tubes (PMT) and provided single-color, or in some cases simultaneous multicolor, photometric data with high time resolution. CCDs have since displaced the use of PMTs in photometers. CCDs offer higher quantum efficiency and two-dimensional imaging arrays, but at a lower speed than PMTs. Without appropriate instruments, the studies of rapid-time domain phenomena took a hiatus. The latest developments and introductions of commercially available Electron-Multiplying CCD (EM-CCD) imagers is driving a renaissance in this field with several new instruments in development.Chimera is a high-speed photometer with simultaneous three-color photometry in the Sloan r’ (562-695 nm), i’ (695-844), and z’ (826-920 nm) bands. The optical design provides well-corrected fields of view of 9.7 arcmin in the z’ band and 6.0 arcmin in r’ and i’ bands. The wide field of view facilitates acquisition and tracking of rapidly moving satellites and allows for a variety of photometric calibration methods. The optical design uses a wide-field collimator, two dichroic beam splitters, and three re-imagers. The design is optimized for the Steward Observatory Kuiper 1.54 m Telescope, although other telescopes can be supported with the exchange of the wide-field collimator. Chimera utilizes three Princeton Instruments Pro-EM HS cameras, which provide data at rates up to 228 Hz in full frame mode. Rates over 1000 Hz are possible by defining photometric regions of interest (ROIs). A highly-modified version of Michael Mommert’s photometric pipeline (PP), originally developed for near-Earth asteroid photometry, is used for data processing. In space surveillance, the optical signature characteristics of rapidly rotating satellites necessitate the use of high-speed multicolor photometers. Satellite photometric analysis takes advantage of reflections off flat surfaces of the satellite. The duration of these flashes are as short as a few ms. The high frame rate of Chimera will allow detailed study of the temporal profile of these reflections, which will allow assessment of the quality and characteristics of the reflective surfaces. The simultaneity of the multicolor measurements ensures that data unambiguously refer to the same surface in the same orientation. In the astronomical community, several authors have reviewed applications for high-speed photometry including astroseismology, transiting exoplanets, and a wide range of high-energy phenomena.In this paper, we document the optical and opto-mechanical design of Chimera and assess the first light performance of the instrument and its cameras and characterize the operational modes of our new instrument. While the unique electron multiplication feature of EM-CCDs provides high frame rates with low noise, other noise sources, which are generally negligible with traditional CCDs, must be considered including dark noise and clock induced charge (CIC). To achieve optimum performance, the astronomer must carefully consider the required temporal bandwidth and field star calibration requirements and operate the CCD at the appropriate gain level. Keywords: Photometry, High-speed, multi-color, electron multiplying CCD, space surveillance

Others

• Pearce, E. C., & Walker, C. (2020, February). Impact of satellite constellations on optical astronomy and recommendations toward mitigations. National Science Foundation NOIRLab. https://baas.aas.org/pub/2020i0206/release/1
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  Principle contributor to the optical measurements section of the Satellite Constellations 1 (SATCON1) workshop. The workshop report concludes that the effects of satellite constellations on astronomical research and on the human experience of the night sky range from “negligible” to “extreme.”
• Pearce, E. C., Krantz, H. R., Block, A., & Rockowitz, K. (2019, March). Night Sky Brightness Model Validation Measurements Final Report. MIT Lincoln Laboratory.
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  In this Study, the Steward Observatory characterized the night sky brightness at three dif-ferent observatory sites surrounding Tucson, AZ under various lunar phases. Sites characterized include Mt. Lemmon (28 km NE of Tucson, 9157’), Mt. Hopkins (60 km S of Tucson, 8585’), and Kitt Peak (68 km WSE of Tucson, 6877’). Measurements were made with a small 180 mm astrograph with a CCD camera and multi-color filter wheel over the full celestial hemisphere us-ing standard relative photometric techniques. In post-processing, the full hemisphere data is combined to determine the true instrumental zero point and all-sky extinction coefficients in each color band. Determination of the all sky extinction coefficient allows the measured NSB to be adjusted to the observed “inside the atmosphere” value. A pair of Unihedron Sky Quality Me-ters (SQMs) provided an independent broadband measurement of the NSB. One of these SQMs was co-mounted with the telescope and provided a secondary measurement of the NSB at each pointing. The second SQM was fixed pointing at the zenith and allowed temporal monitoring of the NSB during each hemisphere collection series. Additionally, a Boltwood Cloud Sensor II recorded weather and overall sky conditions during each collection. Historical comparisons of current NSB at Mt. Hopkins and Kitt Peak are presented and discussed.
• Pearce, E. C., Krantz, H. R., Kirshner, M., Nido, J., & Block, A. (2019, March). Balloon-Borne Telescopes for Cislunar SSA. Office of the Secretary of Defense, Net Assessment (OSD/ONA).
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  In this Study, the potential of balloon-borne telescopes as the Earth-bound component of a comprehensive cislunar SSA sensor architecture is reviewed. First, the observational advantages of balloon-borne telescopes are outlined, including the dramatically decreased scattered moon-light, increased atmospheric transparency, and space-like astronomical seeing over a wide field of view. In this context, the various ballooning options and altitude trades are considered. Modern stratospheric balloons offer several different options to host a cislunar SSA telescope, including high-altitude airships (HAAs) at 20 km, and more traditional super-pressure balloons (SPB) at altitudes up to 35 km. Several stratospheric astronomical telescopes are reviewed that offer relevant technologies and experience. Finally, a developmental plan is outlined including analysis and measurements to refine requirements, a small prototype SSA system, and a path to an objective balloon-borne telescope for cislunar SSA.
• Pearce, E. C. (2018, July). Establishing Space Situational Awareness in Cislunar Space. Office of the Secretary of Defense, Net Assessment (OSD/ONA).
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  Forward looking plenary study discussing the rationale, issues, and challenges establishing Space Situational Awareness (SSA) in cislunar space. This study will begin with a survey of the various proposed missions and orbits and the re-sulting considerations for SSA. This survey will allow the study to narrow the focus and take a deeper dive into the potential use of cislunar space as a parking orbit to insert satellites into low earth orbit. The scenario will be used to exemplify and explore cislunar SSA in general. This scenario is especially concerning as it allows clandestine insertion into LEO of on-orbit spares, co-orbital inspectors, or anti-satellite weapons. This scenario captures all the challenges of cislu-nar SSA in general that make it distinct from traditional circumterrestrial SSA, including (a) large range, (b) difficult viewing geometries that are near the moon from the perspective of an earth-based observer, and (c) complex astrodynamics. The study reviews the various technologies for detection and tracking that are currently used for circumterrestrial SSA and how they can be extended to cislunar SSA. Ground-based and airborne optical systems will be explored in more detail as they provide the best short-term alternative to providing an immediate SSA capability in cislunar space. Finally, recommendations for future directions to study will be made to more comprehensively understand this challenging problem.