Exploration of asteroid (101955) Bennu by the OSIRIS-REx mission has provided an in-depth look at this rubble-pile near-Earth asteroid. In particular, the measured gravity field and the detailed shape model of Bennu indicate significant heterogeneities in its interior structure, compatible with a lower density at its center. Here we combine gravity inversion methods with a statistical rubble-pile model to determine the density and size-frequency distribution (SFD) index of the rubble that constitutes Bennu. The best-fitting models indicate that the SFD of the interior is consistent with that observed on the surface, with a cumulative SFD index of approximately - 2 . 9 . The rubble bulk density is approximately 1.35 g/cm3, corresponding to a 12% macro-porosity. We find the largest rubble particle to be approximately 145 m, whereas the largest void is approximately 10 m.
- Pub Date:
- December 2021
- Near-Earth asteroids;
- Interior structure of asteroids;
- Astrophysics - Earth and Planetary Astrophysics
- 14 pages, 5 figures, accepted to Icarus