The Impact Record on Asteroid Surfaces

Abstract

The surfaces of main-belt and near-Earth asteroids have been carved over the age of the solar system by violent collisions with other asteroids. The craters and related features left behind can be used to interpret each asteroid's unique impact history, which depends on several factors: (i) the dynamical and physical properties of the asteroid (e.g., size, orbit, composition, internal structure), (ii) the nature of the projectile popula- tion striking the asteroid over time, (iii) the asteroid's response to a high- velocity impact, and (iv) the capacity of impact erosion processes and tidal disruption to modify preexisting craters. In this chapter, we describe how numerical hydrocodes, dynamical calculations, and simulations of surface histories allow us to unscramble the complex crater records seen on main belt asteroids like 951 Gaspra and 243 Ida and constrain the processes that have created the impact records. We also present a template for interpret- ing crater history results from near-Earth asteroids like 433 Eros, which will be visited soon by the NEAR spacecraft.