Meteoroid Bombardment of Lunar Poles

Abstract

While the floors of deep lunar craters are largely shielded from solar radiation and thus provide an ideal thermal environment for water ice accumulation, meteoroids on highly inclined orbits can easily access permanently shadowed regions and alter the surface properties via hyper-velocity impacts. Here we consider the detailed topography of lunar poles and a dynamical model of meteoroids to quantify the meteoroid mass fluxes, energy deposition, and impact ejecta mass production rates. Our analysis of regions within $5^\circ$ from the two lunar poles shows that the variations of the meteoroid mass flux, energy flux and ejecta production rate are within $50\%$ of their median values. We find that lunar poles are easily accessible by meteoroid impacts including permanently shadowed regions. We find a positive correlation between the surface slope and the meteoroid ejecta production rate, a finding that suggests a higher impact gardening rate on steep crater walls can facilitate mass wasting.