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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土卫一：冰冻碎片、戒指遗迹，还是新兴海洋世界？


土卫一是土星中型卫星中最小、最靠内的一颗，它的表面布满了坑坑洼洼，没有它的邻居土卫二那样复杂的断裂系统。然而，卡西尼号的测量发现了土卫一冰壳下有海洋的特征，尽管不能排除岩石内部有冰冻冰壳的可能性。土卫一海洋假说激发了人们对土卫一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，这些调查结果（也许令人惊讶）与含有海洋的土卫一（只要它在地质上年轻）是一致的。在这种情况下，土卫一的环起源比原始吸积更受青睐。一个独立开发的土星环间隙形成模型提供了一种在土卫一内形成晚期海洋的潜在机制，并可能有助于土卫二海洋和相关地质活动的发展。土卫一不是一个破旧的遗迹，它可能是土星系统中最年轻的海洋卫星，注定会在未来与土卫二一起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 旗舰级任务的最优先目标。▪ 土卫一的潮汐和自转状态模型支持当今的内海。 ▪ 土卫一的陨石坑、撞击盆地以及缺乏广泛的构造运动与稳定/变暖的海洋相一致。 ▪ 土星环内卡西尼分区的形成为现今土卫一内的海洋提供了一条潜在的途径。 ▪ 如果土卫一今天有海洋，那么它在地质上还很年轻。