Internal rubble properties of asteroid (101955) Bennu

P. Tricarico; D. J. Scheeres; A. S. French; J. W. McMahon; D. N. Brack; J. M. Leonard; P. Antreasian; S. R. Chesley; D. Farnocchia; Y. Takahashi; E. M. Mazarico; D. Rowlands; D. Highsmith; K. Getzandanner; M. Moreau; C. L. Johnson; L. Philpott; E. B. Bierhaus; K. J. Walsh; O. S. Barnouin; E. E. Palmer; J. R. Weirich; R. W. Gaskell; M. G. Daly; J. A. Seabrook; M. C. Nolan; D. S. Lauretta

doi:10.1016/j.icarus.2021.114665

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arXiv · 2108.10416

Internal rubble properties of asteroid (101955) Bennu

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Abstract

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/cm$^3$, 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.

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P. Tricarico, D. J. Scheeres, A. S. French, J. W. McMahon, D. N. Brack, J. M. Leonard, P. Antreasian, S. R. Chesley, D. Farnocchia, Y. Takahashi, E. M. Mazarico, D. Rowlands, D. Highsmith, K. Getzandanner, M. Moreau, C. L. Johnson, L. Philpott, E. B. Bierhaus, K. J. Walsh, O. S. Barnouin, E. E. Palmer, J. R. Weirich, R. W. Gaskell, M. G. Daly, J. A. Seabrook, M. C. Nolan, D. S. Lauretta. 2021-08-23. Internal rubble properties of asteroid (101955) Bennu. https://doi.org/10.1016/j.icarus.2021.114665

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