AI 中文总结
本研究探究DART撞击Didymos系统抛射物的动力学演化，构建高保真抛射物动力学模型，发现多数抛射物两年内逃逸，仅小部分留存或吸积，吸积分布受抛射锥几何强烈控制。
AI 中文摘要
2022年9月26日，DART航天器撞击了Didymos双星系统的小卫星Dimorphos，撞击将尘埃、碎片和巨石抛入近双星环境中。欧洲空间局（ESA）的Hera任务预计于2026年11月抵达该双星系统，对两颗小行星进行表征并详细研究撞击后的后果。本研究旨在探究DART产生的撞击抛射物的动力学演化，并量化它们在Didymos双星系统内的表面吸积模式。研究构建了高保真的抛射物动力学模型，包含多面体小行星引力以及结合掩星效应的太阳辐射压；抛射物初始条件由观测约束的速度-尺寸分布和抛射锥几何生成。共积分了2000万条轨迹以表征抛射物的演化与表面吸积情况。结果显示，超过93.5%的DART产生的抛射物粒子在两年内从系统中逃逸，仅约0.002%保留在近双星环境中；Dimorphos上的沉积层在中低纬度可达约1.5毫米，Didymos上的吸积层大多薄于0.3毫米，但在局部高密度区域可达3-11.5毫米。研究结果表明，大多数DART产生的抛射物会从双星系统中被移除，而一小部分具有动力学意义的抛射物会保留在系统附近或吸积到小行星表面；表面吸积分布受初始抛射锥几何，尤其是锥轴方向的强烈控制。
英文摘要
The DART spacecraft impacted Dimorphos, the small moonlet of Didymos binary system, on 26 September 2022. The impact ejected dust, fragments, and boulders into the near-binary environment. In November 2026, ESA's Hera mission is expected to arrive at the binary system to characterise both asteroids and investigate the post-impact consequences in detail. In this research, we aim to investigate the dynamical evolution of DART-generated impact ejecta and to quantify their surface accretion patterns within the Didymos binary system. High-fidelity ejecta dynamics, including polyhedron asteroid gravity and solar radiation pressure with combined occultations, are constructed. The ejecta initial conditions are generated from the observation-constrained velocity-size distribution and ejecta-cone geometry. In total, 20 million trajectories are integrated to characterise the ejecta evolution and surface accretion. More than 93.5% of DART-generated ejecta particles escape from the system within two years, while only approximately 0.002% remain in the near-binary environment. The deposited layer on Dimorphos reaches the order of 1.5 mm at mid-to-low latitudes. On Didymos, the accreted layer is mostly thinner than 0.3 mm, but may reach 3-11.5 mm in a localised high-density region. The results indicate that, most DART-generated ejecta are removed from the binary system, while a small but dynamically meaningful subset remains near the system or accretes onto the asteroid surfaces. The surface accretion distribution is strongly controlled by the initial ejecta-cone geometry, especially the cone-axis direction.
Comments14 pages, 7 figures
