Abstract
The heat flow and physical properties package measured soil thermal
conductivity at the landing site in the 0.03 to 0.37 m depth range. Six
measurements spanning solar longitudes from
8.0$^\circ$ to 210.0$^\circ$
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. This implies that
any cementation or induration of the soil sampled by the experiments
must be minimal and that the soil surrounding the mole at depths below
the duricrust is unconsolidated. Thermal conductivity data presented
here are the first direct evidence that the atmosphere interacts with
the top most meter of material on Mars.