Temperature map (R) and regular images of Mimas taken by NASA's Cassini spacecraft failed to capture the normal tell-tale clues of a hidden subterranean sea because it is too young for signs of ocean-activity to have appeared at the surface. The giant crater on Mimas' pockmarked surface (L) has drawn comparisons to the Death Star of Star Wars fame. File photo by UPI/NASA/JPL/Goddard/SWRI/SSI |
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Feb. 8 (UPI) -- A new paper by French astronomers out Thursday claims Saturn's so-called "Death Star" moon may in fact be hiding a large liquid sea beneath its icy surface with the condition to support life.
In-depth analysis of data on Mimas, one of Saturn's many moons, gathered by NASA's Cassini mission to Saturn by researchers at France's Paris Observatory indicated an "astonishing" water body between 12 and 18 miles below the surface, according to the study published in the scientific journal Nature.
Mimas has been dubbed "Death Star" because of a massive impact crater on its surface similar to that on the fictional moon-sized space station of the same name from the Star Wars films, central to the legendary franchise.
"The major finding here is the discovery of habitability conditions on a solar system object which we would never, never expect to have liquid water. It's really astonishing," said Paris Observatory scientist Valery Lainey.
"If you look at the surface of Mimas, there's nothing that betrays a subsurface ocean. It's the most unlikely candidate by far."
Given the water on Mimas was in contact with warm rock, Lainey said the existence of life could not be ruled out -- but he caveated the claim by saying that may not have been the case for long enough for life to have the chance to develop.
"Whether it's too young, nobody knows. I would say: why not?"
The shock discovery of a sizeable ocean on such a small heavenly body -- Mimas has a diameter of less than 250 miles -- upends conventional definitions of an ocean moon, setting scientists on a new path in their quest for alien life in the solar system.
The researchers believe the ocean, which appears to comprise more than 50% of Mimas' volume, could have formed as little as 2 million years ago.
The implication of the finding, according to the paper's authors, is that moons with hidden oceans "are tending to become relatively common objects in the Solar System."
Previously discovered oceans, such as that of fellow Saturn moon Enceladus, were mostly given away by surface changes caused by internal dynamics -- in Enceladus' case massive jets and plumes that Cassini was easily able to detect.
"From detailed analysis of Mimas's orbital motion based on Cassini data, with a particular focus on Mimas's periapsis drift, we show that its heavily cratered icy shell hides a global ocean, at a depth of [12-19 miles]," said the scientists.
"Eccentricity damping" measures suggest the ocean was most likely less than 25 million years old and still evolving.
The team's simulations found that the depth at which the icy surface crust becomes liquid water came within 18 miles of the surface as little as 2-3 million years ago, too recent for the tell-tale signs to be reflected in Mimas' surface.
