Browsing by Author "Golombek, M."
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- Seasonal Variations of Soil Thermal Conductivity at the InSight Landing SiteGrott, 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.
- Surface waves and crustal structure on MarsKim, D.; Banerdt, W. B.; Ceylan, S.; Giardini, D.; Lekic, V.; Lognonne, P.; Beghein, C.; Beucler, E.; Carrasco, S.; Charalambous, C.; Clinton, J.; Drilleau, M.; Duran, C.; Golombek, M.; Joshi, R.; Khan, A.; Knapmeyer-Endrun, B.; Li, J.; Maguire, R.; Pike, W. T.; Samuel, H.; Schimmel, M.; Schmerr, N. C.; Stahler, S. C.; Stutzmann, E.; Wieczorek, M.; Xu, Z.; Batov, A.; Bozdag, E.; Dahmen, N.; Davis, P.; Gudkova, T.; Horleston, A.; Huang, Q.; Kawamura, T.; King, Scott D.; McLennan, S. M.; Nimmo, F.; Plasman, M.; Plesa, A. C.; Stepanova, I. E.; Weidner, E.; Zenhausern, G.; Daubar, I. J.; Fernando, B.; Garcia, R. F.; Posiolova, L.; Panning, M. P. (AAAS, 2022-10-28)We detected surface waves from two meteorite impacts on Mars. By measuring group velocity dispersion along the impact-lander path, we obtained a direct constraint on crustal structure away from the InSight lander. The crust north of the equatorial dichotomy had a shear wave velocity of approximately 3.2 kilometers per second in the 5- to 30-kilometer depth range, with little depth variation. This implies a higher crustal density than inferred beneath the lander, suggesting either compositional differences or reduced porosity in the volcanic areas traversed by the surface waves. The lower velocities and the crustal layering observed beneath the landing site down to a 10-kilometer depth are not a global feature. Structural variations revealed by surface waves hold implications for models of the formation and thickness of the martian crust.
- Thermal Conductivity of the Martian Soil at the InSight Landing Site From HP3 Active Heating ExperimentsGrott, 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.) %.