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Browsing by Author "Piqueux, S."

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    Seasonal Variations of Soil Thermal Conductivity at the InSight Landing Site
    Grott, M.; Piqueux, S.; Spohn, T.; Knollenberg, J.; Krause, C.; Marteau, E.; Hudson, T. L.; Forget, F.; Lange, L.; Mueller, N.; Golombek, M.; Nagihara, S.; Morgan, P.; Murphy, J. P.; Siegler, M.; King, Scott D.; Banfield, D.; Smrekar, S. E.; Banerdt, W. B. (American Geophysical Union, 2023-04)
    The heat flow and physical properties package measured soil thermal conductivity at the landing site in the 0.03-0.37 m depth range. Six measurements spanning solar longitudes from 8.0 degrees to 210.0 degrees were made and atmospheric pressure at the site was simultaneously measured using InSight's Pressure Sensor. We find that soil thermal conductivity strongly correlates with atmospheric pressure. This trend is compatible with predictions of the pressure dependence of thermal conductivity for unconsolidated soils under martian atmospheric conditions, indicating that heat transport through the pore filling gas is a major contributor to the total heat transport. Therefore, any cementation or induration of the soil sampled by the experiments must be minimal and soil surrounding the mole at depths below the duricrust is likely unconsolidated. Thermal conductivity data presented here are the first direct evidence that the atmosphere interacts with the top most meter of material on Mars.
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    Thermal Conductivity of the Martian Soil at the InSight Landing Site From HP3 Active Heating Experiments
    Grott, M.; Spohn, T.; Knollenberg, J.; Krause, C.; Hudson, T. L.; Piqueux, S.; Mueller, N.; Golombek, M.; Vrettos, C.; Marteau, E.; Nagihara, S.; Morgan, P.; Murphy, J. P.; Siegler, M.; King, Scott D.; Smrekar, S. E.; Banerdt, W. B. (American Geophysical Union, 2021-07-14)
    The heat flow and physical properties package (HP3) 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 HP3 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 μm 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 (Formula presented.) kg m−3, indicating soil porosities of (Formula presented.) %.