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 800 m to 5 km 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 3 Ga is ~5.5 m2/Myr. With this diffusivity, after 3 Ga, a 1 km diameter crater is reduced to approximately ~52% of its initial depth and a 300 m diameter crater is reduced to only ~7% of its initial depth, and craters smaller than ~200–300 m 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. Key Points Lunar crater degradation can be treated as a topographic diffusion problemDegradation state can be used to estimate the age of individual cratersThe mean diffusivity of the Moon's surface over the last 3 Ga is ~5.5 m2/Myr