Asymmetric Crater Relaxation on an Ice‐Rich Ceres Driven by Insolation

Ceres has a high ice content within its crust and is the closest dwarf planet to the sun. The resultant high insolation levels at Ceres' surface (in comparison to the outer solar system) leads to high variations in surface temperature, which is dependent on both latitude and orientation of the slope (i.e., equatorward‐ or poleward‐facing). As the rheology of ice within the crust will be highly temperature dependent, we hypothesize that asymmetric viscous relaxation occurs at the largest craters on Ceres driven by insolation variations. We measure the slopes of equatorward‐ and poleward‐facing crater walls and use finite element method simulations of simulated Cerean craters to interpret our observations. Our simulations predict a complicated asymmetric evolution for relaxing craters. For most craters >50 km in diameter, we predict shallower equatorward‐facing walls than their poleward‐facing counterparts, due to their receiving more direct insolation and lower resulting viscosities. Craters ≥130 km in diameter will have equatorward‐ and poleward‐facing walls that have large latitudes, and therefore, temperature differences. Thus, latitude may affect crustal viscosity more than slope aspect and result in shallower poleward‐facing walls. The asymmetric crater walls observed and modeled here may be a result of an ice‐rich crust on Ceres deforming due to a modest amount of insolation driven viscous relaxation.