Thermophysical Properties and Surface Heterogeneity of Landing Sites on MarsFrom Overlapping Thermal Emission Imaging System (THEMIS) Observations

Orbitally derived thermal inertia (TI) values of surfaces allow for remote interpretation ofrock and sediment physical characteristics. The evolving local times of the Mars OdysseyThermal Emission Imaging System (THEMIS) mission have enabled surface temperature datacollection over multiple seasons and local times over ∼9 Mars years (MY). We utilize thishigher temporal resolution data set to separate TI values of individual materials withinTHEMIS pixels (100 m sampling). In this study, we focus on geologic units within Gusev, Gale,and Jezero crater landing sites to determine their respective TI and ground-truth ourmethods. We use the KRC model to predict temperatures for a range of homogeneous andtwo-component thermophysical mixing scenarios (laterally and vertically heterogeneous),and compare those to THEMIS brightness temperatures. The Gusev and Gale crater resultsare consistent with rover-based evaluations, indurated or clast-covered sands. The best-fi tscenarios along the Jezero crater volcanic fl oor unit show low to moderate TI valuesrepresentative of coarse sediment, volcaniclastic, or pyroclastic rocks. The light toned unitand western fan deposits both indicate sands and a moderate TI component; we interpretthis as heavy fracturing within the rock. Diffi culties in modeling some THEMIS temperaturesare attributed to daily weather eff ects, local atmospheric dust variability, and real surfacechanges over time (e.g., dust deposition and removal); we also observe that sometemperature observations lead to non-unique modeled physical solutions. Nevertheless,these methods can still rule out a signifi cant range of material properties and providemeaningful geologic information about Mars’ surface.