Publications associated with Planetary Science


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

Nature Geoscience Springer Nature 12 (2019) 242-246

S Clemett, K Thomas-Keprta, S Van Wal, M Yoshikawa, J Bellerose, S Bhaskaran, C Boyles, CM Elder, D Farnocchia, A Harbison, A Knight, B Kennedy, N Martinez-Vlasoff, N Mastrodemos, T McElrath, W Owen, R Park, L Swanson, B Rush, Y Takahashi, K Yetter, D Velez, C Thayer, C Adam

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.


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