Ejecta Emplacement on the Martian Satellites
Ejecta Emplacement on the Martian Satellites
复制标题
火星卫星上的喷射物安置
DOI：
10.1006/icar.1997.5858
复制
发表时间：
1998
期刊：
影响因子：
3.2
通讯作者：
P. Thomas
中科院分区：
文献类型：
--
作者：
P. Thomas
摘要将火星卫星上的喷出物特征与弹道侵位和下坡运动模型进行了比较。火卫一上的斯蒂克尼大陨石坑周围喷出物的不对称分布似乎最容易解释，如果该陨石坑形成时，火卫一只是比现在稍微远离火星（由于潮汐演化），旋转和潮汐效应允许低速物质向陨石坑以东几公里处扩散，但它不允许陨石坑的大部分喷出物被发射到临时火星轨道。解释斯蒂克尼喷出物分布的另一个条件是，陨石坑的挖掘是在重力主导的状态下进行的。斯蒂克尼喷出物的分布与沟的形态和潜在的长距离下坡运动没有密切关系。在火卫二上，南极附近的一次大撞击产生的喷出物似乎也是在重力状态下形成的陨石坑。旧陨石坑的形态，喷出物积水的证据和陨石坑密度数据表明，从这个大的影响喷出物已受到显着的再分配下坡。这个陨石坑相对于火卫二比斯蒂克尼相对于火卫一要大得多;由此产生的更大的喷出物覆盖物和火卫二上可能更大的地震震动可能有助于解释火星卫星惊人的不同外观。
Abstract Ejecta features on the martian satellites are compared to models of ballistic emplacement and downslope motion. The asymmetric distribution of ejecta around the large crater Stickney on Phobos appears most easily explained if the crater were formed when Phobos was only slightly farther from Mars than at present (due to tidal evolution), where rotational and tidal effects allow spreading of low velocity material several kilometers to the east of the crater, but which do not allow a large fraction of the crater's ejecta to be launched into temporary Mars orbit. An additional condition needed to explain the distribution of Stickney's ejecta is that the crater excavation occurred in a gravity-dominated regime. The distribution of Stickney's ejecta is not closely related to the patterns of grooves nor to potential long-distance downslope motion. On Deimos, ejecta from a large impact near the south pole also appear to have been produced by cratering largely in the gravity regime. The morphology of older craters, evidence of ejecta ponding, and crater density data indicate that the ejecta from this large impact have been subject to significant redistribution downslope. This crater is much larger relative to Deimos than Stickney is to Phobos; the resulting greater ejecta cover and possibly much greater seismic shaking on Deimos may help explain the strikingly different appearances of the martian moons.