The Cratering History of Asteroid (2867) Steins

TL;DR

This study analyzes the cratering history of asteroid (2867) Steins using OSIRIS imagery, estimating its surface age and examining factors influencing crater retention, revealing a complex evolution possibly affected by large impacts and reshaping processes.

Contribution

It introduces a detailed cratering history analysis of Steins using impact models and crater scaling laws, highlighting the asteroid's surface age and unique crater distribution.

Findings

Estimated surface age ranges from a few hundred Myrs to over 1 Gyr.

Identified a lack of small craters below 0.6 km, suggesting unique surface evolution.

Possible influence of large impacts or YORP reshaping on crater record.

Abstract

The cratering history of main belt asteroid (2867) Steins has been investigated using OSIRIS imagery acquired during the Rosetta flyby that took place on the 5th of September 2008. For this purpose, we applied current models describing the formation and evolution of main belt asteroids, that provide the rate and velocity distributions of impactors. These models coupled with appropriate crater scaling laws, allow the cratering history to be estimated. Hence, we derive Steins' cratering retention age, namely the time lapsed since its formation or global surface reset. We also investigate the influence of various factors -like bulk structure and crater erasing- on the estimated age, which spans from a few hundred Myrs to more than 1Gyr, depending on the adopted scaling law and asteroid physical parameters. Moreover, a marked lack of craters smaller than about 0.6km has been found and interpreted as a result of a peculiar evolution of Steins cratering record, possibly related either to the formation of the 2.1km wide impact crater near the south pole or to YORP reshaping.