Mimas, the smallest and innermost of Saturn's mid-sized moons, has a heavily cratered surface devoid of the intricate fracture systems of its neighbor, Enceladus. However, Cassini measurements identified a signature of an ocean under Mimas’ ice shell, although a frozen ice shell over a rocky interior could not be ruled out. The Mimas ocean hypothesis has stimulated inquiry into Mimas’ geologic history and orbital evolution. Here, we summarize the results of these investigations, which (perhaps surprisingly) are consistent with an ocean-bearing Mimas as long as it is geologically young. In that case, a ring origin for Mimas is favored over primordial accretion. An independently developed model for the formation of a gap in Saturn's rings provides a potential mechanism for generating a late-stage ocean within Mimas and may have assisted in the development of Enceladus’ ocean and associated geologic activity. Rather than a battered relic, Mimas may be the youngest ocean moon in the Saturn system, destined to join Enceladus as an active world in the future. The presence of oceans within Saturn's mid-sized moons also has implications for the habitability of Uranus’ moons; the Uranus system was chosen as the highest priority target for the next NASA Flagship-class mission.▪Models of Mimas’ tides and rotation state support a present-day internal ocean.▪Mimas’ craters, impact basin, and lack of widespread tectonism are compatible with a stable/warming ocean.▪The formation of the Cassini Division within Saturn's rings provides a potential pathway to a present-day ocean within Mimas.▪If Mimas has an ocean today, it is geologically young.

中文翻译：

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Mimas：冰冻碎片、戒指遗物，还是新兴的海洋世界？


米马斯是土星中最小、最里面的中型卫星，其表面布满了严重的陨石坑，没有其邻居土卫二错综复杂的断裂系统。然而，卡西尼号的测量确定了米马斯冰壳下海洋的特征，尽管不能排除岩石内部有冰冻的冰壳。米马斯海洋假说激发了对米马斯地质历史和轨道演化的探究。在这里，我们总结了这些调查的结果，只要它在地质上是年轻的，这些结果（也许令人惊讶）与含海洋的 Mimas 是一致的。在这种情况下，Mimas 的环原点比原始吸积更受欢迎。一个独立开发的在土星环中形成间隙的模型为在 Mimas 内产生晚期海洋提供了一种潜在的机制，并可能有助于土卫二海洋的发展和相关地质活动。米马斯不是破败的遗物，而是土星系统中最年轻的海洋卫星，注定在未来会加入土卫二，成为一个活跃的世界。土星中型卫星中海洋的存在也对天王星卫星的宜居性产生影响;天王星系统被选为下一个 NASA 旗舰级任务的最高优先级目标。▪Mimas 的潮汐和旋转状态模型支持当今的内部海洋。▪Mimas 的陨石坑、撞击盆地和缺乏广泛的构造活动与稳定/变暖的海洋相容。▪在土星环内形成卡西尼分区为通往 Mimas 内当今海洋提供了一条潜在的途径。▪如果 Mimas 今天有海洋， 它在地质上很年轻。