Degradation mechanisms and efficiency of heavily cratered regions on Ceres

TL;DR

This study investigates crater degradation on Ceres by analyzing crater equilibrium features across eight sites, revealing that crater degradation is more intense on Ceres than on the Moon due to higher impact flux.

Contribution

It applies an extended crater equilibrium model to Ceres, providing new insights into the mechanisms and conditions of crater degradation on this dwarf planet.

Findings

Crater equilibrium on Ceres resembles that on the Moon but is denser.

Crater degradation per impact on Ceres is comparable or higher than on the Moon.

Impact flux on Ceres is much higher, leading to elevated crater degradation.

Abstract

Ceres, the dwarf planet in the main asteroid belt, hosts heavily cratered surfaces where craters are continuously eroded mainly due to impact bombardment with a limited influence by non-impact processes. Over continuous bombardment, such regions experience both crater production and erasure, eventually ceasing the crater population growth. This end-state, known as crater equilibrium, provides key information to constrain the mechanisms of crater degradation. The present study applies a recently extended crater equilibrium model to the crater equilibrium features and constrains the conditions for crater degradation on Ceres. We select eight heavily cratered sites as our test locations across four quadrangles (two sites per quadrangle) and collect crater counts using Dawn Framing Camera imagery. All sites exhibit cumulative size-frequency distributions (CSFD) with slopes slightly shallower than a power law of -2 at diameters below a few kilometers, strongly suggesting that the tested sites are at crater equilibrium. Our results show that the crater equilibrium state on Ceres resembles that on the Moon but is denser. Performing model fitting with crater counting data under negligible ejecta blanketing for crater erasure, we further show that crater degradation per single crater production on Ceres is comparable to or higher than that on the Moon. Combining this finding and the impact flux on Ceres, which is orders of magnitude higher than that on the Moon, suggests that crater degradation is much more elevated on Ceres than on the Moon, despite its denser crater population.