Mimas, Saturn's largest moon, may be generating enough heat to sustain an ocean of water beneath the moon's icy surface. Recent modeling of the Herschel impact crater, the most prominent feature on the moon's surface, and the lack of tectonic activity support the hypothesis of a geologically young inland ocean surrounded by a relatively thin ice shell.
Researchers at the Southwestern Research Institute (SwRI) in San Antonio (Texas, USA) reached the following conclusions. A curious libration, a fluctuation in Mimas' rotational characteristics, which often indicates the existence of an internal ocean,
Despite these shifts, scientists initially thought of Mimas' surface as an ice sheet, because other oceanic worlds, like Enceladus with its geysers or other moons of Saturn, exhibit different signs of geological activity. Mimas does not have these features.
Mimas appeared to be an unlikely candidate for the presence of an ocean because its frozen surface with one huge impact crater did not suggest the existence of such activity. We are talking about a new class of “stealth ocean,” which does not manifest itself in any way.
When scientists examined the Herschel impact crater's formation, they found that the ice shell at the time of impact would have to be at least 55 km thick. Nonetheless, observations and modeling suggest that it is now less than 30 km thick. In other words, the inland ocean has heated and expanded since the impact.
Researchers claim that if Mimas is given the status of a moon with an internal ocean, it would enable us to investigate its evolution and formation, which would help us to better understand Saturn's rings and medium-sized moons, as well as to estimate the prevalence of oceanic moons, in particular, around Uranus.
On December 26, the findings of the study will be published in the journal Geophysical Research Letters.
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