Impact-induced deformation away from the impact point on small asteroids

Abstract

ABSTRACT We investigated the propagation of energy and momentum inside a small gravitational aggregate asteroid following a hypervelocity impact, comparable to NASA’s Double Asteroid Redirection Test (DART) on asteroid Dimorphos. We show that the impact energy damps rapidly inside different kinds of granular structures, unable to reach the antipodal hemisphere of the impact. However, global reshaping of the asteroid after the formation of a sizeable (${\gt}1/3$ of target size) crater causes meter-range displacement of boulders on the antipodal hemisphere due to mass rearrangement to achieve a new equilibrium shape. As a result, a surface depression opposite to the crater is formed, which may produce some surface refreshment. The boulder mass ejection following the synthetic DART-like impact is estimated to be at least $0.1\, {{\ \rm per\ cent}}$ of the mass of the Dimorphos-like target, in agreement with recent detections of boulders ejected from the actual DART impact.