Robin Colas Q, Duchene Alexia, Murdoch Naomi, Vincent Jean-Baptiste, Lucchetti Alice, Pajola Maurizio, Ernst Carolyn M, Daly R Terik, Barnouin Olivier S, Raducan Sabina D, Michel Patrick, Hirabayashi Masatochi, Stott Alexander, Cuervo Gabriela, Jawin Erica R, Trigo-Rodriguez Josep M, Parro Laura M, Sunday Cecily, Vivet Damien, Mimoun David, Rivkin Andrew S, Chabot Nancy L
Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO), Université de Toulouse, Toulouse, France.
DLR Institute of Planetary Research, Berlin, Germany.
Nat Commun. 2024 Jul 30;15(1):6203. doi: 10.1038/s41467-024-50147-w.
Planetary defense efforts rely on estimates of the mechanical properties of asteroids, which are difficult to constrain accurately from Earth. The mechanical properties of asteroid material are also important in the interpretation of the Double Asteroid Redirection Test (DART) impact. Here we perform a detailed morphological analysis of the surface boulders on Dimorphos using images, the primary data set available from the DART mission. We estimate the bulk angle of internal friction of the boulders to be 32.7 ± 2. 5° from our measurements of the roundness of the 34 best-resolved boulders ranging in size from 1.67-6.64 m. The elongated nature of the boulders around the DART impact site implies that they were likely formed through impact processing. Finally, we find striking similarities in the morphology of the boulders on Dimorphos with those on other rubble pile asteroids (Itokawa, Ryugu and Bennu). This leads to very similar internal friction angles across the four bodies and suggests that a common formation mechanism has shaped the boulders. Our results provide key inputs for understanding the DART impact and for improving our knowledge about the physical properties, the formation and the evolution of both near-Earth rubble-pile and binary asteroids.
行星防御工作依赖于对小行星力学特性的估计，而从地球上很难准确地对其进行限制。小行星物质的力学特性在对双小行星重定向测试（DART）撞击的解释中也很重要。在这里，我们使用DART任务提供的主要数据集——图像，对双小行星迪莫弗斯（Dimorphos）表面的巨石进行了详细的形态分析。通过对34颗分辨率最高、大小在1.67 - 6.64米之间的巨石的圆度测量，我们估计这些巨石的内摩擦堆积角为32.7±2.5°。DART撞击点周围巨石的细长形状表明它们可能是通过撞击过程形成的。最后，我们发现迪莫弗斯上巨石的形态与其他碎石堆小行星（糸川小行星、龙宫小行星和贝努小行星）上的巨石形态有惊人的相似之处。这导致这四个天体的内摩擦角非常相似，并表明一种共同的形成机制塑造了这些巨石。我们的结果为理解DART撞击以及提高我们对近地碎石堆小行星和双小行星的物理特性、形成和演化的认识提供了关键依据。
