THEMIS and CTX‐based assessment of crater rim thermal inertia over the Martian southern hemisphere region

Abstract On Mars, neighboring craters of similar diameter show variations in rim thermal inertia. In this study, thermal inertia (TI) was calculated using Mars Odyssey Thermal Emission Imaging System (THEMIS) nighttime images acquired during the southern hemisphere Martian autumn, a period with minimal fine dust influence. One hundred and thirty‐seven craters of different diameters across 21 TI scenes were analyzed, encompassing Gale Crater and its surroundings. Morphological parameters such as depth‐diameter ratio (d/D), radii variation (RV), rim irregularity (RI), and mantle rim percentage (MRP) were derived using Mars Reconnaissance Orbiter (MRO) Context camera (CTX) images. Two hypotheses were tested: Hypothesis I—Crater rim thermal inertia influenced by crater degradation during the southern hemisphere Martian autumn, and Hypothesis II—Crater rim thermal inertia influenced by crater rim regolith mantling during the southern hemisphere Martian autumn. Multilevel regression models were used to test the hypotheses. Hypothesis I was rejected, and Hypothesis II was found to be statistically significant ( p < 0.05), indicating crater rim TI variations are largely influenced by regolith mantling, reflecting dominant depositional activity. During the southern hemisphere autumn on Mars, atmospheric dust levels are relatively low; however, significant surface dust remains, likely redistributed by dust storms from the preceding summer season.