Impact craters that form on every planetary body provide a record of planetary surface evolution. On heavily-cratered surfaces, new craters that form often overlap older craters, but it is unknown how the presence of older craters alters impact crater formation. We use overlapping complex crater pairs on the lunar surface to constrain this process and find that crater rims are systematically lower where they intersect antecedent crater basins. However, the rim morphology of the new crater depends on both the depth of the antecedent crater and the degree of overlap between the two craters. Our observations suggest that transient rim collapse is altered by antecedent topography, leading to circumferential distribution of rim materials in the younger crater. This study represents the first formalization of the influence of antecedent topography on rim morphology and provides process insight into a common impact scenario relevant to the geology of potential Artemis landing sites.

The mass transport of volatiles on Mars represents a seasonally changing load onto the lithosphere of the planet. Much like on Earth, as mass is redistributed across the planet, the surface responds in a complex manner becoming displaced downwards or upwards. The magnitude and extent of displacement depend on the properties of the load and mechanical properties of the planetary interior. Based on new estimates of the height variation of the seasonal polar cap (SPC) we predict local surface displacements of up to tens of millimeters with a strong degree 1 signal throughout the Martian year. The long-wavelength portion of the displacement is potentially observable, with a magnitude of a few millimeters, located away from the seasonal polar cap where we could realistically measure it with a landed or orbital mission. We also model the direct contribution of this process to observable time variable gravity where we find the odd zonal coefficients to be in line with previous measurements, although with a smaller magnitude. Future measurements of this displacement could be used to help elucidate the composition of the mantle and crust of Mars, using this process as a probe into the Martian interior. Furthermore, more refined measurements of time-variable gravity would be a powerful tool in constraining the pole-to-pole volatile cycle present on Mars.