Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface
Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface
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DOI：
10.1038/s41561-019-0326-6
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发表时间：
2019-03
影响因子：
18.3
通讯作者：
K. Walsh;E. Jawin;R. Ballouz;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. Daly;D. DellaGiustina;J. Dworkin;C. Elder;D. Golish;A. Hildebrand;R. Malhotra;J. Marshall;P. Michel;M. Nolan;M. Perry;B. Rizk;A. Ryan;S. Sandford;D. Scheeres;H. Susorney;F. Thuillet;D. Lauretta;the OSIRIS-REx Team
中科院分区：
文献类型：
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作者：
K. Walsh;E. Jawin;R. Ballouz;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. Daly;D. DellaGiustina;J. Dworkin;C. Elder;D. Golish;A. Hildebrand;R. Malhotra;J. Marshall;P. Michel;M. Nolan;M. Perry;B. Rizk;A. Ryan;S. Sandford;D. Scheeres;H. Susorney;F. Thuillet;D. Lauretta;the OSIRIS-REx Team
小型、公里级大小的近地小行星预计将拥有年轻且经常更新的表面，原因有两个：它们起源的主要小行星带中碰撞破坏频繁，一旦它们成为近地小行星，热或潮汐过程就会对它们产生作用。在这里，我们展示了 OSIRIS-REx（起源、光谱解释、资源识别和安全-风化层探索者）任务对近地小行星 (101955) Bennu 上众多大型候选撞击坑的早期测量结果，表明其表面年龄在 1 亿至 10 亿年之间，早于 Bennu 作为近地小行星的预期持续时间。我们还观察到许多破裂的巨石，其形态表明自巨石暴露在表面以来相当长的时间内受到撞击或热过程的影响。然而，地表也显示出最近发生的大规模运动的迹象：地势低洼处的巨石群、小陨石坑的缺乏和大陨石坑的填充。最古老的特征可能记录了贝努时代在主小行星带发生的事件。
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.