Title

Exogenic basalt on asteroid (101955) Bennu

Authors

D. N. DellaGiustina, The University of Arizona
H. H. Kaplan, Space Science and Engineering Division
A. A. Simon, NASA Goddard Space Flight Center
W. F. Bottke, Space Science and Engineering Division
C. Avdellidou, Observatoire de la Côte d'Azur
M. Delbo, Observatoire de la Côte d'Azur
R. L. Ballouz, The University of Arizona
D. R. Golish, The University of Arizona
K. J. Walsh, Space Science and Engineering Division
M. Popescu, Universidad de la Laguna
H. Campins, University of Central Florida
M. A. Barucci, Université PSL
G. Poggiali, Osservatorio Astrofisico Di Arcetri
R. T. Daly, Johns Hopkins University Applied Physics Laboratory
L. Le Corre, Planetary Science Institute
V. E. Hamilton, Space Science and Engineering Division
N. Porter, The University of Arizona
E. R. Jawin, Smithsonian National Museum of Natural History
T. J. McCoy, Smithsonian National Museum of Natural History
H. C. Connolly, The University of Arizona
J. L.Rizos Garcia, Universidad de la Laguna
E. Tatsumi, Universidad de la Laguna
J. de Leon, Universidad de la Laguna
J. Licandro, Universidad de la Laguna
S. Fornasier, Université PSL
M. G. Daly, York University, Centre For Research in Earth and Space Science
M. M. Al Asad, The University of British Columbia
L. Philpott, The University of British Columbia
J. Seabrook, York University, Centre For Research in Earth and Space Science
O. S. Barnouin, Johns Hopkins University Applied Physics Laboratory
B. E. Clark, Ithaca College
M. C. Nolan, The University of Arizona
E. S. Howell, The University of Arizona

Document Type

Article

Publication Date

1-1-2021

Abstract

© 2020, The Author(s), under exclusive licence to Springer Nature Limited. When rubble-pile asteroid 2008 TC3 impacted Earth on 7 October 2008, the recovered rock fragments indicated that such asteroids can contain exogenic material1,2. However, spacecraft missions to date have only observed exogenous contamination on large, monolithic asteroids that are impervious to collisional disruption3,4. Here, we report the presence of metre-scale exogenic boulders on the surface of near-Earth asteroid (101955) Bennu—the 0.5-km-diameter, rubble-pile target of the OSIRIS-REx mission5 that has been spectroscopically linked to the CM carbonaceous chondrite meteorites6. Hyperspectral data indicate that the exogenic boulders have the same distinctive pyroxene composition as the howardite–eucrite–diogenite (HED) meteorites that come from (4) Vesta, a 525-km-diameter asteroid that has undergone differentiation and extensive igneous processing7–9. Delivery scenarios include the infall of Vesta fragments directly onto Bennu or indirectly onto Bennu’s parent body, where the latter’s disruption created Bennu from a mixture of endogenous and exogenic debris. Our findings demonstrate that rubble-pile asteroids can preserve evidence of inter-asteroid mixing that took place at macroscopic scales well after planetesimal formation ended. Accordingly, the presence of HED-like material on the surface of Bennu provides previously unrecognized constraints on the collisional and dynamical evolution of the inner main belt.

Publication Name

Nature Astronomy

Volume Number

5

First Page

31

Last Page

38

Issue Number

1

DOI

10.1038/s41550-020-1195-z

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