Geomorphic map and science target identification on the Shackleton-de Gerlache ridge

Analogous to similar maps prepared in support of the Apollo missions, we produced a geomorphic map at a scale of 1:8000 of Artemis III Areas of Interest 001 and 004 on the Shackleton-de Gerlache ridge and the adjacent Shackleton crater rim to support future landed missions in the area. Using 1 m/pixel Lunar Reconnaissance Orbiter Narrow Angle Camera mosaics and 5 m/pixel topographic maps derived from Lunar Orbiter Laser Altimeter observations, we differentiated among ten units, all related to slope-controlled regolith processes or impacts, as well as among seven crater classes according to degradation state. Almost 85% of the map area outside of Shackleton crater are characterized by “elephant hide” textures at different intensities, which are mostly a function of the local slope angle. No signatures of the Shackleton ejecta blanket or a nearby Tycho ejecta ray were found in the morphology and crater statistics of our map area. We did, however, identify a potential lobate scarp and expanded on block detections by previous authors. We used our map to devise three consecutive traverse sequences named “Safe”, “Extended”, and “Increased risk”, which are each focused on maximizing sample yield and diversity to meet scientific objectives, while maintaining defined safety parameters. The three traverse sequences travel across respective maximum slopes of 10°, 15°, and 16°, have lengths of 3.6 km, 11.9 km, and 11.4 km, and each pass within sampling range of several block occurrences. The second traverse sequence “Extended” ends at a location with a direct line of sight into Shackleton crater, which would enable high-resolution observations using secondary illumination. The third traverse sequence “Increased risk” would conclude by reaching what might be a degraded Shackleton impact melt pond inside an adjacent, highly degraded crater. However, this sequence includes challenging illumination conditions and slopes up to 16° that warrant further investigations and hazard assessment. It should not be attempted until after key science questions are addressed during the preceding two traverse sequences. Based on their sizes, locations, and minor to moderate coverages by regolith, we interpret at least some of the blocks along each traverse sequence to be crustal fragments ejected during the Shackleton event or Shackleton rim material ejected by smaller craters. Thus, multiple locations along each traverse sequence provide the potential to not only investigate the unique south polar regolith, possible age signatures from Tycho, and potential volatiles in local micro-PSRs, but also the ages of Shackleton and the South Pole-Aitken basin.