CLEW (compact lunar explorer for water): state of the art IR spectrometer for a lunar CubeSat orbiter beyond BIRCHES

Determining the abundance, origin, movement, and storage of water on the Moon with far greater certainty is an ongoing primary goal of lunar exploration. Essential constraints would come from measuring water absorption features repeatedly over the same swaths as a function of time of day from a nearly polar orbit with equatorial periapsis, the goal proposed for BIRCHES (Broadband InfraRed Compact High Resolution Exploration Spectrometer) on the original Lunar Ice Cube mission. Establishing these constraints would be the goal of CLEW, Compact Lunar Explorer for Water, the instrument described in this paper. CLEW has mass, volume, and power requirements comparable but performance, including imaging capability, greatly improved relative to BIRCHES. High heritage CLEW would utilize the NASA GSFC Compact Thermal Imager (CTI), state of the art self-calibrating focal plane array combined with SIDECAR ASIC instrument electronics, combined with an active cooling system and optics similar to CLuHME (Compact Lunar Hydration and Mineralogy Experiment). The platform would likely be significantly more robust and ‘roomy’, due to availability of high-performance thermal protection components and a larger 12U platform. Planned addition of a compact context camera would enhance image interpretation.