Exploring the gravitational anomaly of Mount Sharp in Gale crater, Mars

Gale crater, where the Mars Science Laboratory rover Curiosity landed in 2012, has particularly interesting topography with a raised mound in the center. Based off of a vertical rod terrain corrected gravity it is expected that this raised center, called Aeolis Mons or Mount Sharp, would give a positive gravitational anomaly. However, the free air gravity data, collected by measuring doppler shifts from three Mars-orbiting satellites, indicates only a negative anomaly from the terrain of the crater. We present two hypotheses to explain this difference: one, the gravity data is too low-resolution to show this positive anomaly, and two, Mount Sharp is comprised of lower density material than the surrounding terrain. Some sedimentary rocks in Gale crater are thought to be mudstones with the central mound itself being of varying sedimentary origin. When fitted with the proposed densities for mound and crater rim, the current forward model predicts the negative gravitational anomaly observed in the free air gravity. In this work, we explore sedimentological explanations for a low-density anomaly contributing to a negative gravitational anomaly in the center of Gale crater.