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.Comment: Accepted by Planetary and Space Scienc