Crustal Density Differences Along Mars' Dichotomy Boundary From Gravity and Topography

Seismic data for Mars has provided constraints on the thickness of its crust, but its density and how much it varies spatially, especially across the hemispherical dichotomy, is still undetermined. We apply a novel constraint in the analysis of spacecraft tracking data to determine Mars' gravity field that allows for the determination of the density of the north and south directly from the data. We find a density of kg for the north and kg for the south. This result is independent from the seismic results, and consistent with seismic constraints that indicate the difference between the north and south should not be greater than 200 kg . Accounting for the higher densities of volcanoes changes the difference slightly, still within the seismic constraint. Our density results provide additional, independent constraints for crustal thickness modeling and elucidating the origin of the dichotomy.