Axial ratios of boulders on asteroid Itokawa

Abstract

Fragments can be simply modeled as triaxial ellipsoids with axis lengths a, b, c, such that their shapes are described by the axial ratios b/a and c/a. Some laboratory experiments of catastrophic disruptions showed that the distributions of the fragment axial ratios b/a and c/a are peaked at values close 0.7 and 0.5, respectively. In this study, the shapes of boulders on asteroid Itokawa are measured from the images of spacecraft Hayabusa in order to investigate whether these shapes resemble the shapes of the fragments.