Bennu’s near-Earth lifetime of 1.75 million years inferred from craters on its boulders

R.-L. Ballouz (), K. J. Walsh, O. S. Barnouin, D. N. DellaGiustina, M. Al Asad, E. R. Jawin, M. G. Daly, W. F. Bottke, P. Michel, C. Avdellidou, M. Delbo, R. T. Daly, E. Asphaug, C. A. Bennett, E. B. Bierhaus, H. C. Connolly, D. R. Golish, J. L. Molaro, M. C. Nolan, M. Pajola, B. Rizk, S. R. Schwartz, D. Trang, C. W. V. Wolner and D. S. Lauretta
Additional contact information
R.-L. Ballouz: University of Arizona
K. J. Walsh: Southwest Research Institute
O. S. Barnouin: The Johns Hopkins University Applied Physics Laboratory
D. N. DellaGiustina: University of Arizona
M. Al Asad: University of British Columbia
E. R. Jawin: Smithsonian Institution
M. G. Daly: York University, Toronto
W. F. Bottke: Southwest Research Institute
P. Michel: Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange
C. Avdellidou: Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange
M. Delbo: Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange
R. T. Daly: The Johns Hopkins University Applied Physics Laboratory
E. Asphaug: University of Arizona
C. A. Bennett: University of Arizona
E. B. Bierhaus: Lockheed Martin Space
H. C. Connolly: University of Arizona
D. R. Golish: University of Arizona
J. L. Molaro: Planetary Science Institute
M. C. Nolan: University of Arizona
M. Pajola: INAF-Astronomical Observatory of Padova
B. Rizk: University of Arizona
S. R. Schwartz: University of Arizona
D. Trang: HIGP/University of Hawaii at Mānoa
C. W. V. Wolner: University of Arizona
D. S. Lauretta: University of Arizona

Nature, 2020, vol. 587, issue 7833, 205-209

Abstract: Abstract An asteroid’s history is determined in large part by its strength against collisions with other objects1,2 (impact strength). Laboratory experiments on centimetre-scale meteorites3 have been extrapolated and buttressed with numerical simulations to derive the impact strength at the asteroid scale4,5. In situ evidence of impacts on boulders on airless planetary bodies has come from Apollo lunar samples6 and images of the asteroid (25143) Itokawa7. It has not yet been possible, however, to assess directly the impact strength, and thus the absolute surface age, of the boulders that constitute the building blocks of a rubble-pile asteroid. Here we report an analysis of the size and depth of craters observed on boulders on the asteroid (101955) Bennu. We show that the impact strength of metre-sized boulders is 0.44 to 1.7 megapascals, which is low compared to that of solid terrestrial materials. We infer that Bennu’s metre-sized boulders record its history of impact by millimetre- to centimetre-scale objects in near-Earth space. We conclude that this population of near-Earth impactors has a size frequency distribution similar to that of metre-scale bolides and originates from the asteroidal population. Our results indicate that Bennu has been dynamically decoupled from the main asteroid belt for 1.75 ± 0.75 million years.

Date: 2020
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.nature.com/articles/s41586-020-2846-z Abstract (text/html)
Access to the full text of the articles in this series is restricted.

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:nat:nature:v:587:y:2020:i:7833:d:10.1038_s41586-020-2846-z

Ordering information: This journal article can be ordered from
https://www.nature.com/

DOI: 10.1038/s41586-020-2846-z

Access Statistics for this article

Nature is currently edited by Magdalena Skipper

More articles in Nature from Nature
Bibliographic data for series maintained by Sonal Shukla () and Springer Nature Abstracting and Indexing ().