Updated

Updated · spacedaily.com · Aug 7

Astronomers Confirm 20-30 km Ocean Beneath Mimas, Dating It to 5-15 Million Years

Updated

Updated · spacedaily.com · Aug 7

Astronomers Confirm 20-30 km Ocean Beneath Mimas, Dating It to 5-15 Million Years

Q: Could a hidden, 25-million-year-old ocean beneath Mimas's frozen craters hold the secret to life in our solar system?

Possibly, but there is no evidence yet that Mimas’s hidden ocean harbors life, and it is too early to call it a leading candidate for that secret. What makes Mimas important is not proof of biology, but proof that a moon that looks dead on the outside may still contain liquid water inside. The 2024 Nature study by Valéry Lainey and colleagues found that Cassini data on Mimas’s orbit, libration and orbital drift are best explained by a global ocean buried about 20 to 30 kilometers beneath the ice. That would make Mimas an unexpected addition to the solar system’s roster of ocean worlds. For life, liquid water alone is not enough. Scientists still need to know the ocean’s chemistry, salinity, energy sources and whether the water interacts with rock below, a key process that can supply nutrients and chemical disequilibria useful for life. None of that has been measured at Mimas. Unlike Enceladus, which vents plume material that spacecraft can sample, Mimas shows no known plumes, fractures or direct chemical evidence from its interior. Its possible youth also cuts both ways. If the ocean formed only within the past 5 to 25 million years, that may explain the cratered, ancient-looking surface. But a young ocean may also have offered less time for prebiotic chemistry or biology to develop, depending on its conditions. So Mimas could expand the search for habitable environments, but at present it is a compelling ocean candidate, not a demonstrated abode of life.

1 articles · Updated · spacedaily.com · Aug 7

Nature results published in 2024 show Saturn’s moon Mimas likely holds a global ocean 20-30 km below its cratered ice shell, making the hidden sea geologically young rather than ancient.
Cassini tracking of Mimas’s libration and the slow drift of its closest orbital point matched models with liquid water far better than a fully frozen moon or an oddly shaped rocky core.
394-km-wide Mimas had long looked inert because its surface is heavily cratered and lacks the fractures or plumes seen on Enceladus, but researchers say a young ocean may not yet have reshaped the exterior.
The finding broadens the search for ocean worlds by showing old-looking icy moons can hide liquid water, though scientists still do not know Mimas’s ocean chemistry, salinity or how long it will remain liquid.