P060-06
Lunar-surface UV Photometric Investigation of Exospheres (LUPINE): Thermal Modeling of Payload in a Relevant Daylit Environment
Monday, 14 December 2020: 16:20
Virtual
Millan Diaz-Aguado, Millennium Engineering and Integration, NASA Ames Research Center, Moffett Field, CA, United States, Rick Doe, SRI International Menlo Park, Menlo Park, CA, United States, Asti Bhatt, SRI International, Menlo Park, CA, United States, Kurt D Retherford, Southwest Research Inst, San Antonio, TX, United States, John Noto, Computational Physics Inc., North Chelmsford, MA, United States and Edwin Mierkiewicz, Embry-Riddle Aeronautical University, Daytona Beach, FL, United States
Abstract:
Direct upward remote sensing of the moon’s exosphere from a surface vantage can address production of water-related lunar volatiles as well as their exospheric loss, ballistic transport, and ultimate adsorption in permanently shadowed regions (PSRs). Far UV (FUV) dayside measurements of atomic oxygen, liberated from regolith by energetic solar protons and micrometeorite impact, can provide critical insight into the endogenic lunar water cycle by constraining total column density [O] at site of production. A notional Lunar-surface UV Photometric Investigation of Exospheres (LUPINE) instrument is designed to exploit solar-pumped atomic oxygen fluorescence at 130.4-nm, in a manner similar to the Apollo 17 UV Spectrometer (UVS) experiment [Fastie 1973; Feldman and Morrison, 1991] and the LRO Lyman-alpha Mapping Project (LAMP) spectrograph [Cook et al., 2013], by implementing a zenith-directed FUV photometer from the lunar surface at low (± 10°) selenographic latitude during the lunar day.
Atomic oxygen production from solar energetic particle impact sources is thought to maximize in near solar noon [Sarantos et al., 2012], and the lander-embedded zenith-directed LUPINE photometer, in contrast to UVS and LAMP twilight measurements from orbit, can potentially capture the full column abundance of lunar regolith liberated oxygen. Herein we describe adaptation of FUV reflective optics, pulse-counting electronics, and scattered-light-suppression technologies developed for LEO FUV photometry for the challenging thermal environment of the daylit lunar surface. Preliminary thermal modeling and TVAC measurements of heritage FUV photometer components suggests that, if allowed to shed ~16W of waste heat into the bus of a reference Commercial Lunar Payload Services (CLPS) lander, the LUPINE photometer will be kept sufficiently cool to limit dark current to less than 20 counts/s. This level of dark signal enables OI 130.4-nm 3-sigma detection threshold of ~1 mR (oxygen surface density ~ 100 cm-3) for assumed 2-hour integrations.
