The icy Saturn moon Mimas may be a “stealth” ocean world, according to new research.
MimasSmall and internal Sat’s major moons are believed to generate just the right amount of heat to support a surface ocean of liquid water. Recent simulations of the Moon’s Herschel impact basin—the most striking feature on its highly cratered surface—support the existence of a geologically young interior ocean surrounded by a thin ice sheet, with a lack of tectonics on Mimas. A statement (opens in new tab) From the Southwest Research Institute (SwRI) in San Antonio, Texas.
“In NASA’s Declining Days Cassini “The mission to Saturn identified a curious release, or oscillation, in the rotation of the spacecraft Mimas, which often indicates the ability of a geologically active body to support an internal ocean,” Alyssa Rhoden, co-author of the new study and a scientist at SwRI, said in the statement.
Related: 10 Unusual Ocean Worlds in Our Solar System (Photos)
Despite this wobble, however, Mimas’ highly cratered surface led scientists to initially consider the moon to be a frozen ice mass. That’s because most ocean worlds are geyser-spouting Enceladus, one of Saturn’s other moons—shows fracturing and other signs of geological activity. Mimas, however, has no discernible tectonic characteristics.
“Mimas seemed an unlikely candidate, with its icy, highly cratered surface marked by a large impact crater that made it look very much like a small moon. Death Star From ‘Star Wars,'” Rhoden said in the statement. “If Mimas has an ocean, it represents a new class of small, ‘stealthy’ ocean worlds with surfaces that don’t betray the presence of an ocean.”
When modeling Herschel’s formulation impact basin, scientists found that Mimas’ ice must have been at least 34 miles (55 kilometers) thick at the time of impact. Meanwhile, observations of Mimosa and models of its internal heating indicate that its current ice thickness is less than 19 miles (30 km), the report says.
These measurements suggest that the interior ocean has been warming and expanding since the basin formed. What’s more, the researchers were only able to reproduce the shape of the basin when they factored an internal ocean into their models.
“We found that Herschel could not have formed on the current thick ice sheet without destroying the ice sheet at the point of impact,” study lead author and University of Arizona postdoctoral researcher Adeen Denton said in the report. “If Mimas has an ocean today, the ice sheet has been thinning since Herschel’s formation, which could also explain the lack of fractures on Mimas. If Mimas is a growing ocean world, that poses important barriers to formation, evolution, and life. Medium-sized all Moons of Saturn.”
These new models challenge scientists’ current understanding of thermal-orbital evolution, Rhoden said in the report.
“Assessing Mimas’ status as an ocean moon will gauge models of its formation and evolution,” Rhoden said. “This will help us understand better Rings of Saturn and medium-sized moons as well as the prevalence of potentially habitable oceanic moons, particularly on Uranus. Mimas is a compelling target for further investigation.”
Their findings were Published on December 26, 2022 (opens in new tab)In Geophysical Research Letters.
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