Cape Canaveral, Florida –
Astronomers have discovered the best evidence yet of a vast, young ocean beneath the icy exterior of Saturn’s Death Star-like small moon.
A French-led research team analyzed changes in Mimas’ orbit and rotation and found that an ocean hidden 12 to 18 miles (20 to 30 km) beneath the frozen crust is more likely than an elongated rocky core. It was reported on Wednesday.
Scientists published their findings based on observations made by NASA’s Cassini spacecraft. The spacecraft observed Saturn and its more than 140 moons for more than a decade before it entered the ringed planet’s atmosphere and burned up in 2017.
Only 250 miles (400 kilometers) in diameter, this heavily cratered moon lacks the fissures and geysers that are typical signs of underground activity, like Saturn’s Enceladus and Jupiter’s Europa.
“Mimas is probably the least likely place in the global ocean, and more generally, for liquid water to exist,” co-author Valérie Rainey of the Paris Observatory said in an email. “So it looks like it could be a habitable world. But no one knows how long it will take for life to form.”
The results were published in the journal Nature.
Half of Mimas’ volume is thought to be filled with ocean, Rainey said. However, given the moon’s small size, it accounts for only 1.2% to 1.4% of Earth’s oceans. Despite Mimas being so small, she boasts the second largest impact crater among the solar system’s moons. This is why Mimas is compared to the fictional space station Death Star from Star Wars.
“The idea that relatively small icy moons could harbor young oceans is exciting,” Matija Chukwu of the SETI Institute and Alyssa Rose Roden of the Southwest Research Institute wrote in an accompanying editorial. Ta. They did not participate in the study.
It is thought to be between 5 million and 15 million years old, Rainey said, and is too young to have left any traces on the moon’s surface, so the overall temperature of this subsurface ocean is near freezing. But water temperatures could be even warmer on the ocean floor, he said.
Co-author Nick Cooper from Queen Mary University of London said the presence of a “very young” ocean of liquid water makes Mimas a prime candidate for studying the origins of life.
Discovered in 1789 by British astronomer William Herschel, Mimas is named after a giant from Greek mythology.
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