Craters, Boulders and Regolith of (101955) Bennu Indicative of an Old and Dynamic Surface

Walsh, K J ; Jawin, E R ; Ballouz, R-L ; Barnouin, O S ; Bierhaus, E B ; Jr, H C Connolly ; Molaro, J L ; McCoy, T J ; Delbo, M ; Hartzell, C M(Maryland Univ, College Park, MD, United States)

关键词: ASTEROID BELTS;    ASTEROIDS;    CRATERS;    FRACTURES (MATERIALS);    GEOLOGY;    IMAGING TECHNIQUES;    METEORITES;    MORPHOLOGY;    REGOLITH;    SIZE DISTRIBUTION;    THREE DIMENSIONAL MODELS;    TOPOGRAPHY;   

RP-ID  :  GSFC-E-DAA-TN67699

学科分类：空间科学

美国|英语

来源: NASA Technical Reports Server

【 摘 要 】

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.