Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface

K J Walsh, E Jawin, O Barnouin, E Bierhaus, H Connolly, J Molaro, T McCoy, M Delbo, C Hartzell, M Pajola, S Schwartz, D Trang, E Asphaug, K Becker, C Beddingfield, C Bennett, W Bottke, K Burke, B Clark, M DalyD DellaGiustina, J Dworkin, C Elder, D Golish, A Hildebrand, R Malhotra, J Marshall, P MIchel, M Nolan, M Perry, B Rizk, A Ryan, S Sanford, D Scheeres, Hannah Susorney, F Thuillet, D Lauretta, The OSIRIS-REx Team

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Abstract

Small, kilometre-sized near-Earth asteroids are expected to have young and frequently refreshed surfaces for two reasons: collisional disruptions are frequent in the main asteroid belt where they originate, and thermal or tidal processes act on them once they become near-Earth asteroids. Here we present early measurements of numerous large candidate impact craters on near-Earth asteroid (101955) Bennu by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) mission, which indicate a surface that is between 100 million and 1 billion years old, predating Bennu’s expected duration as a near-Earth asteroid. We also observe many fractured boulders, the morphology of which suggests an influence of impact or thermal processes over a considerable amount of time since the boulders were exposed at the surface. However, the surface also shows signs of more recent mass movement: clusters of boulders at topographic lows, a deficiency of small craters and infill of large craters. The oldest features likely record events from Bennu’s time in the main asteroid belt.
Original languageEnglish
Pages (from-to)242-246
Number of pages5
JournalNature Geoscience
Volume12
Issue number4
Early online date19 Mar 2019
DOIs
Publication statusPublished - Apr 2019

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    Walsh, K. J., Jawin, E., Barnouin, O., Bierhaus, E., Connolly, H., Molaro, J., McCoy, T., Delbo, M., Hartzell, C., Pajola, M., Schwartz, S., Trang, D., Asphaug, E., Becker, K., Beddingfield, C., Bennett, C., Bottke, W., Burke, K., Clark, B., ... The OSIRIS-REx Team (2019). Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface. Nature Geoscience, 12(4), 242-246. https://doi.org/10.1038/s41561-019-0326-6