Thermal Stability of Ice at Shackleton Crater: Implications for Water Ice Detection for the Chang’E-7 Mission

Abstract The candidate landing region for China’s Chang’E-7 (CE-7) lunar exploration mission is near Shackleton crater at the lunar south pole, and the CE-7 mission will perform in situ detection of water ice. We model the thermal stability of water ice in Shackleton crater and its surroundings at higher resolutions than previous remote sensing observations, considering the thermophysical properties of lunar regolith suitable for low-temperature conditions at the south pole. The effects of regolith thermal properties, influenced by different packings of lunar regolith, on the thermal stability of water ice in both permanently shadowed regions (PSRs) and non-PSRs are analyzed. Most of the surface of lunar regolith inside Shackleton crater is favorable for the stable preservation of water ice. For the PSRs inside the crater, more loosely packed lunar regolith results in lower annual mean temperatures at depths shallower than ∼0.03 m below the surface than those for densely packed regolith, suggesting that water ice could be more easily preserved in the shallow layers of loosely packed regolith in PSRs. Cold traps for some volatiles that require lower temperatures than water to persist over geological timescales are also identified; these cold traps, however, are noncontiguous due to the variation in local topography. Outside Shackleton crater, there are numerous cold traps with sizes down to ∼100 m. The identified cold traps could preserve a rich history of volatile accumulation and serve as targets for in situ exploration of water ice during the CE-7 mission.