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Bennu's near-Earth lifetime of 1.75 million years inferred from craters on its boulders.
Ballouz, R-L; Walsh, K J; Barnouin, O S; DellaGiustina, D N; Asad, M Al; Jawin, E R; Daly, M G; Bottke, W F; Michel, P; Avdellidou, C; Delbo, M; Daly, R T; Asphaug, E; Bennett, C A; Bierhaus, E B; Connolly, H C; Golish, D R; Molaro, J L; Nolan, M C; Pajola, M; Rizk, B; Schwartz, S R; Trang, D; Wolner, C W V; Lauretta, D S.
Afiliação
  • Ballouz RL; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA. rballouz@orex.lpl.arizona.edu.
  • Walsh KJ; Southwest Research Institute, Boulder, CO, USA.
  • Barnouin OS; The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA.
  • DellaGiustina DN; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
  • Asad MA; University of British Columbia, Vancouver, British Columbia, Canada.
  • Jawin ER; Smithsonian Institution, Washington, DC, USA.
  • Daly MG; York University, Toronto, Ontario, Canada.
  • Bottke WF; Southwest Research Institute, Boulder, CO, USA.
  • Michel P; Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France.
  • Avdellidou C; Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France.
  • Delbo M; Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France.
  • Daly RT; The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA.
  • Asphaug E; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
  • Bennett CA; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
  • Bierhaus EB; Lockheed Martin Space, Littleton, CO, USA.
  • Connolly HC; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
  • Golish DR; Department of Geology, Rowan University, Glassboro, NJ, USA.
  • Molaro JL; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
  • Nolan MC; Planetary Science Institute, Tucson, AZ, USA.
  • Pajola M; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
  • Rizk B; INAF-Astronomical Observatory of Padova, Padua, Italy.
  • Schwartz SR; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
  • Trang D; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
  • Wolner CWV; HIGP/University of Hawaii at Manoa, Honolulu, HI, USA.
  • Lauretta DS; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
Nature ; 587(7833): 205-209, 2020 11.
Article em En | MEDLINE | ID: mdl-33106686
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.

Texto completo: 1 Base de dados: MEDLINE Idioma: En Ano de publicação: 2020 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Idioma: En Ano de publicação: 2020 Tipo de documento: Article