Dimorphos 巨石的长期轨道演化及其对陨石起源的启示
Long-term orbital evolution of Dimorphos boulders and implications on the origin of meteorites
AI总结：
本研究基于 HST 观测，数值模拟了 DART 撞击后弹射的 Dimorphos 巨石群未来 2 万年的轨道演化，发现其将在约 6 和 15 千年后可能撞击火星并形成小撞击坑，为部分地球陨石起源于百米级近地小行星碰撞提供了证据。
摘要：
利用哈勃太空望远镜对 Didymos-Dimorphos 系统的近期观测，在 DART 航天器撞击期间，识别出 37 块尺寸为 4 至 7 米、从系统中弹射出的巨石。在本研究中，我们研究了与所探测到的巨石尺寸相似的一群巨石的轨道演化。利用近期对巨石弹射速度的估计，我们在未来 2 万年的时间尺度上数值推演了该巨石群的动力学。我们发现，弹射速度和非引力效应不足以显著改变其长期演化。与地球的最小轨道相交距离（MOID）将在约 2.5 千年时达到，但不会低于 0.02 天文单位（au）。相反，火星的 MOID 将在四次情况中非常小，两次接近 6 千年，另两次接近 15 千年。因此，它们未来有可能撞击火星。鉴于火星大气稀薄，我们预计这些巨石将完整抵达地面并挖掘出小型撞击坑。本文结果进一步表明，在地球上发现的一些陨石起源于约 100 米的近地小行星与约 1 米大小的抛射体之间的碰撞。
英文摘要：
By using recent observations of the Dydimos-Dimorphos system from the Hubble Space Telescope, 37 boulders with a size of 4 to 7 meters ejected from the system during the impact with the DART spacecraft were identified. In this work, we studied the orbital evolution of a swarm of boulders with a similar size to that of the detected ones. By using recent estimates for the ejection velocity of the boulders, we numerically propagated the dynamics of the swarm for 20 kyr in the future. We found that the ejection velocities and the non-gravitational effects are not strong enough to change the secular evolution significantly. The minimum orbit intersection distance (MOID) with the Earth will be reached in about 2.5 kyr, but it will not fall below 0.02 au. On the contrary, the Mars MOID will be very small in four instances, two near 6 kyr and the other two near 15 kyr. Therefore, there may be a chance for them to impact Mars in the future. Given the rarefaction of the Martian atmosphere, we expect the boulders to arrive intact on the ground and excavate a small impact crater. The results presented here provide a further indication that some meteorites found on Earth originated in collisions of $\sim$100 m near-Earth asteroids with projectiles of $\sim$1 m in size.
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