Interior Structure of Bennu from Shape and Gravity Data

Introduction

The arrival of the OSIRIS-REx spacecraft at asteroid (101955) Bennu will allow us to determine its shape, topography, rotation, and gravitational field. We will determine the range of interior structure models of Bennu which are compatible with the observed shape and gravity field. This includes modeling of possible deviations from an homogeneous interior, the size and density of possible heterogeneities, and the depth and density structure of possible layers.

Science Goals and Objectives

We will determine the range of interior mass density distributions which are compatible with the observed shape and gravity field.

Methodology

The proposed work builds upon the experience acquired by the PI as a Participating Scientist for the Dawn at Vesta phase, and as a Guest Investigator for the Dawn at Ceres phase. We will use a global gravity inversion method which is particularly well suited at providing the range of interior structure solutions which reproduce exactly the observed shape and gravity field of Bennu. The method is designed to work for bodies with arbitrary shape and mass distributions. While the gravity inversion problem is under constrained and in general can admit a wide range of solutions, this method allows us to perform a global analysis to identify the features of the interior which are most persistent over the observed range of solutions. Such features can include possible surface density anomalies, which can be correlated with other surface observations and enhance their interpretation.