Crater degradation on the lunar maria: Topographic diffusion and the rate of erosion on the Moon

Landscape evolution on the Moon is dominated by impact cratering in the post-maria period. In this study, we mapped 800m to 5km diameter craters on >30% of the lunar maria and extracted their topographic profiles from digital terrain models created using the Kaguya Terrain Camera. We then characterized the degradation of these craters using a topographic diffusion model. Because craters have a well-understood initial morphometry, these data provide insight into erosion on the Moon and the topographic diffusivity of the lunar surface as a function of time. The average diffusivity we calculate over the past 3Ga is similar to 5.5m(2)/Myr. With this diffusivity, after 3Ga, a 1km diameter crater is reduced to approximately similar to 52% of its initial depth and a 300m diameter crater is reduced to only similar to 7% of its initial depth, and craters smaller than similar to 200-300m are degraded beyond recognition. Our results also allow estimation of the age of individual craters on the basis of their degradation state, provide a constraint on the age of mare units, and enable modeling of how lunar terrain evolves as a function of its topography.