S3LA - the single-photon ounting Laser Altimeter for the SER3NE mission to the Moon

Kurzfassung

Selenes Explorer for Roughness, Regolith, Resources, Neutrons and Elements (SER3NE) is a small satellite mission proposal to perform gamma-ray and neutron spectroscopy, near-infrared spectroscopy, and laser altimetry, the latter of which will yield surface roughness, and albedo observations at unprecedented resolution. The aim of the mission is to characterize the lunar surface to unravel its volatile content and associated delivery processes, to uncover the geological processes that shaped the Moon, to prospect lunar resources for ISRU at future landing sites, to determine the exact neutron lifetime, and to investigate the orbital evolution of the Earth-Moon system. We report on the development of S3LA, a single-photon counting laser altimeter and its scientific goals within the mission context. S3LA facilitates a different detection scheme when compared to conventional laser altimeters in planetary research. An array of singlephoton avalanche diodes (SPADs) on a CMOS chip is used for ultra-low light level detection down to a few photons per pixel. A lightweight combined transmitter-receiver optics with a small aperture diameter (8 cm) ensures the compatibility to the tight mass budget of the mission.