TY - JOUR
T1 - Thermophysical Properties and Surface Heterogeneity of Landing Sites on Mars From Overlapping Thermal Emission Imaging System (THEMIS) Observations
AU - Ahern, Alexandra A.
AU - Rogers, A. Deanne
AU - Edwards, Christopher S.
AU - Piqueux, Sylvain
N1 - Funding Information:
This work was funded by the Mars Odyssey Project. The authors thank Kimberly Murray for her assistance in reprocessing the THEMIS PBT images and Luca Montabone for sharing a beta version of the climatology database for us to use, before it was eventually published. They are grateful to our two reviewers for thorough, constructive comments.
Publisher Copyright:
© 2021. The Authors.
PY - 2021/6
Y1 - 2021/6
N2 - Orbitally derived thermal inertia (TI) values of surfaces allow for remote interpretation of rock and sediment physical characteristics. The evolving local times of the Mars Odyssey Thermal Emission Imaging System (THEMIS) mission have enabled surface temperature data collection over multiple seasons and local times over ∼9 Mars years (MY). We utilize this higher temporal resolution data set to separate TI values of individual materials within THEMIS 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 our methods. We use the KRC model to predict temperatures for a range of homogeneous and two-component thermophysical mixing scenarios (laterally and vertically heterogeneous), and compare those to THEMIS brightness temperatures. The Gusev and Gale crater results are consistent with rover-based evaluations, indurated or clast-covered sands. The best-fit scenarios along the Jezero crater volcanic floor unit show low to moderate TI values representative of coarse sediment, volcaniclastic, or pyroclastic rocks. The light toned unit and western fan deposits both indicate sands and a moderate TI component; we interpret this as heavy fracturing within the rock. Difficulties in modeling some THEMIS temperatures are attributed to daily weather effects, local atmospheric dust variability, and real surface changes over time (e.g., dust deposition and removal); we also observe that some temperature observations lead to non-unique modeled physical solutions. Nevertheless, these methods can still rule out a significant range of material properties and provide meaningful geologic information about Mars’ surface.
AB - Orbitally derived thermal inertia (TI) values of surfaces allow for remote interpretation of rock and sediment physical characteristics. The evolving local times of the Mars Odyssey Thermal Emission Imaging System (THEMIS) mission have enabled surface temperature data collection over multiple seasons and local times over ∼9 Mars years (MY). We utilize this higher temporal resolution data set to separate TI values of individual materials within THEMIS 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 our methods. We use the KRC model to predict temperatures for a range of homogeneous and two-component thermophysical mixing scenarios (laterally and vertically heterogeneous), and compare those to THEMIS brightness temperatures. The Gusev and Gale crater results are consistent with rover-based evaluations, indurated or clast-covered sands. The best-fit scenarios along the Jezero crater volcanic floor unit show low to moderate TI values representative of coarse sediment, volcaniclastic, or pyroclastic rocks. The light toned unit and western fan deposits both indicate sands and a moderate TI component; we interpret this as heavy fracturing within the rock. Difficulties in modeling some THEMIS temperatures are attributed to daily weather effects, local atmospheric dust variability, and real surface changes over time (e.g., dust deposition and removal); we also observe that some temperature observations lead to non-unique modeled physical solutions. Nevertheless, these methods can still rule out a significant range of material properties and provide meaningful geologic information about Mars’ surface.
KW - KRC
KW - Mars
KW - THEMIS
KW - surface
KW - thermal inertia
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U2 - 10.1029/2020JE006713
DO - 10.1029/2020JE006713
M3 - Article
AN - SCOPUS:85108584119
SN - 2169-9097
VL - 126
JO - Journal of Geophysical Research: Planets
JF - Journal of Geophysical Research: Planets
IS - 6
M1 - e2020JE006713
ER -