Mapping of Patterned Regolith Textures Near the Lunar South Pole

Lunar slopes have distinct patterned regolith textures, but their formation mechanism remains enigmatic. We mapped the distribution of these “elephant hide” texture (EHT) occurrences in and out of shadow near the south pole (90°S to 88°S) at a scale of 1:25,000 and 1:20,000 to test if permanently shadowed regions (PSRs) have unique regolith properties relative to non-shadowed areas (polar and equatorial). We recorded the presence or absence of EHT occurrences in grid-map cells (5 and 1 km2) using Lunar Reconnaissance Orbiter Narrow Angle Camera images of illuminated terrain, and Korea Pathfinder Lunar Orbiter ShadowCam images of permanently and temporarily shadowed terrain. We find that diffuse lighting does not interfere with the ability to identify textures. We observed that EHT has a similar likelihood to occur on shallow slopes ≤ 5° in both illuminated and permanently shadowed terrain, with no difference in texture morphology across temperature boundaries or from PSR to PSR. This suggests that regolith properties in PSRs that are relevant to EHT formation are not significantly different from those of the illuminated surface. We also observed variations of EHT across the same slopes and EHT on near-horizontal surfaces (≤ 3°) within ~500 m of the foot of slopes. This suggests that patterned regolith textures are formed by down-slope transport of loose regolith, likely driven by both episodic and continuous disturbances.