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Thermal Conductivity of the Martian Soil at the InSight Landing Site From HP 3 Active Heating Experiments
Author(s) -
Grott M.,
Spohn T.,
Knollenberg J.,
Krause C.,
Hudson T. L.,
Piqueux S.,
Müller N.,
Golombek M.,
Vrettos C.,
Marteau E.,
Nagihara S.,
Morgan P.,
Murphy J. P.,
Siegler M.,
King S. D.,
Smrekar S. E.,
Banerdt W. B.
Publication year - 2021
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1029/2021je006861
Subject(s) - thermal conductivity , mars exploration program , cementation (geology) , martian , geothermal gradient , martian soil , mineralogy , thermal , materials science , thermal effusivity , thermal conductivity measurement , atmospheric temperature range , heat flow , soil science , analytical chemistry (journal) , martian surface , geology , composite material , chemistry , thermodynamics , geophysics , thermal resistance , thermal contact conductance , astrobiology , physics , environmental chemistry , cement
The heat flow and physical properties package (HP 3 ) of the InSight Mars mission is an instrument package designed to determine the martian planetary heat flow. To this end, the package was designed to emplace sensors into the martian subsurface and measure the thermal conductivity as well as the geothermal gradient in the 0–5 m depth range. After emplacing the probe to a tip depth of 0.37 m, a first reliable measurement of the average soil thermal conductivity in the 0.03–0.37 m depth range was performed. Using the HP 3 mole as a modified line heat source, we determined a soil thermal conductivity of 0.039 ± 0.002 W m −1 K −1 , consistent with the results of orbital and in‐situ thermal inertia estimates. This low thermal conductivity implies that 85%–95% of all particles are smaller than 104–173 μ m and suggests that soil cementation is minimal, contrary to the considerable degree of cementation suggested by image data. Rather, cementing agents like salts could be distributed in the form of grain coatings instead. Soil densities compatible with the measurements are 1211 − 113 + 149kg m −3 , indicating soil porosities of 63 − 9 + 4 %.