Regional heat flow and subsurface temperature patterns at Elysium Planitia and Oxia Planum areas, Mars

Abstract

Elysium Planitia and Oxia Planum are plains located near the Martian dichotomy. Lately, both regions have been extensively analyzed due to the major role that they play in the InSight and ExoMars missions. InSight landed in Elysium Planitia and will obtain the first direct measurement of surface heat flow on Mars. Similarly, the Rosalind Franklin rover on ExoMars 2020 will also provide useful information to understand the thermal state of the planet from data acquired in Oxia Planum, which is the preferred landing site. The proximity of the Martian dichotomy to the area surrounding both landing locations is an important source of spatial variability. In this work, we have modeled the heat flow and the subsurface temperature in the regions adjacent to both landing sites considering the regional context. In order to do so, we have solved the heat conduction equation by means of a finite element analysis and by taking into account topography, crustal composition, and crustal and megaregolith thicknesses. Our results indicate that the spatial variation in these parameters for the region surrounding the InSight landing site involves maximum differences in subsurface temperatures and surface heat flows between highlands and lowlands of about 67% and 16%, respectively. In regard to the area surrounding ExoMars landing site, these differences can reach 28% for subsurface temperatures, and 3% for surface heat flows. Crustal and megaregolith thicknesses together with the thermal properties of the megaregolith layer are the most influential factors affecting heat flows and temperature patterns. We also find that regional variations related to the dichotomy boundary are unlikely to have a large effect on the geothermal heat flux at the InSight and ExoMars landing sites.