A New View of the Lunar South Pole from the Lunar Orbiter Laser Altimeter (LOLA)

Abstract

Abstract Upcoming missions to the lunar south pole require detailed maps over large areas to fully characterize landing sites locally and regionally and to place their data into proper geologic context. To that end, we enhanced the Lunar Orbiter Laser Altimeter altimetry data set for the south polar region, from which we produced new maps of topography, topographic roughness, and permanently shadowed regions (PSRs). The roughness maps reveal a diversity of terrains characterized by hectometer-scale roughness that is controlled in this region primarily by cratering and downslope mass transport. The south polar region is littered with linear roughness features of order ∼1–10 km wide and approximately tens to hundreds of kilometers long hypothesized to be secondary impacts within extended ejecta rays. Nonuniformities in these features could reflect variations in secondary impactor properties and/or target terrain properties. Poleward of 80° S, the PSR cumulative size–frequency distribution (CSFD) shows an approximately power-law behavior whose exponent has a spatial variation of ∼10%. PSRs with areas <1 km2 contain 15% ± 5% of the total PSR area. Finally, we studied the effect of false positives and false negatives on the accuracy of the measured PSR CSFD and on the area for any individual PSR. The new maps presented here have many applications in the science and exploration of the lunar south polar region, such as geologic mapping and traverse planning.