Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
Planetary Science Institute, Tucson, AZ, USA.
Nat Commun. 2019 Mar 19;10(1):1291. doi: 10.1038/s41467-019-09213-x.
During its approach to asteroid (101955) Bennu, NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft surveyed Bennu's immediate environment, photometric properties, and rotation state. Discovery of a dusty environment, a natural satellite, or unexpected asteroid characteristics would have had consequences for the mission's safety and observation strategy. Here we show that spacecraft observations during this period were highly sensitive to satellites (sub-meter scale) but reveal none, although later navigational images indicate that further investigation is needed. We constrain average dust production in September 2018 from Bennu's surface to an upper limit of 150 g s averaged over 34 min. Bennu's disk-integrated photometric phase function validates measurements from the pre-encounter astronomical campaign. We demonstrate that Bennu's rotation rate is accelerating continuously at 3.63 ± 0.52 × 10 degrees day, likely due to the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, with evolutionary implications.
在接近小行星（101955）贝努期间，美国宇航局的起源、光谱解释、资源识别和安全风化层探测器（OSIRIS-REx）航天器对贝努的近环境、光度特性和自转状态进行了调查。尘埃环境、天然卫星或意外的小行星特征的发现将对任务的安全和观测策略产生影响。在这里，我们表明，在此期间，航天器观测对卫星（亚米级尺度）非常敏感，但没有发现任何卫星，尽管后来的导航图像表明需要进一步调查。我们将 2018 年 9 月从贝努表面产生的平均尘埃量限制在上限 150g s，平均持续 34 分钟。贝努的盘积分光度相位函数验证了预相遇天文观测的测量结果。我们证明，贝努的自转速度正在以 3.63±0.52×10 度/天的速度持续加速，可能是由于 Yarkovsky-O'Keefe-Radzievskii-Paddack（YORP）效应所致，这具有进化意义。
