Possible Anthropogenic Contributions to the LAMP-observed Surficial Icy Regolith within Lunar Polar Craters: A Comparison of Apollo and Starship Landings

This work assesses the potential of midsized and large human landing systems to deliver water from their exhaust plumes to cold traps within lunar polar craters. It has been estimated that a total of between 2 and 60 T of surficial water was sensed by the Lunar Reconnaissance Orbiter Lyman Alpha Mapping Project on the floors of the larger permanently shadowed south polar craters. This intrinsic surficial water sensed in the far-ultraviolet is thought to be in the form of a 0.3%–2% icy regolith in the top few hundred nanometers of the surface. We find that the six past Apollo Lunar Module midlatitude landings could contribute no more than 0.36 T of water mass to this existing, intrinsic surficial water in permanently shadowed regions (PSRs). However, we find that the Starship landing plume has the potential, in some cases, to deliver over 10 T of water to the PSRs, which is a substantial fraction (possibly >20%) of the existing intrinsic surficial water mass. This anthropogenic contribution could possibly overlay and mix with the naturally occurring icy regolith at the uppermost surface. A possible consequence is that the origin of the intrinsic surficial icy regolith, which is still undetermined, could be lost as it mixes with the extrinsic anthropogenic contribution. We suggest that existing and future orbital and landed assets be used to examine the effect of polar landers on the cold traps within PSRs.