Astronomers have made a groundbreaking discovery, uncovering a hidden ocean buried beneath the icy surface of Mimas, a moon of Saturn famously resembling the Death Star from the Star Wars franchise.
This revelation places Mimas among an elite group of moons in our solar system known to harbor subterranean oceans, including Saturn's Titan and Enceladus, as well as Jupiter's Europa and Ganymede.
Mimas' Vast Subsurface Ocean
The finding emerged from meticulous analysis conducted by a French-led team from Observatoire de Paris, who scrutinized data collected during NASA's Cassini mission. Previous assumptions about Mimas considered it merely a solid chunk of ice. However, new evidence suggests otherwise.
Researchers examined changes in Mimas' orbit and rotation, concluding that a hidden ocean lies approximately 12 to 18 miles beneath its battered crust. This revelation challenges previous notions and offers profound implications for the search for habitable worlds beyond our own.
Discovered in 1789 by English astronomer William Herschel, Mimas garnered attention due to its resemblance to the Death Star, primarily characterized by an enormous impact crater. Despite its icy exterior, Mimas lacked the typical signs of subsurface activity observed on moons like Enceladus and Europa.
The research team's study findings, published in the journal Nature on Wednesday, shed light on Mimas' unique dynamics. Contrary to initial assumptions, Mimas' rotation and orbital motion indicate the presence of a global ocean, estimated to occupy half of Mimas' volume, beneath its surface.
The team estimates that the ocean lies approximately 12.4 to 18.6 miles (20 to 30 kilometers) beneath the moon's icy shell.
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Unexpected Discovery of 'Young' Ocean
In this handout image provided by the National Aeronautics and Space Administration (NASA), the planet Saturn's "Death Star" moon Mimas is shown from a distance of approximately 28,000 miles (45,000 kilometers), taken by NASA's spacecraft Cassini-Huygens in its closest approach to the pock-marked moon on January 30, 2017. The lighting, reflected from Saturn, has been enhanced by NASA.
Valéry Lainey, co-author of the study and an astronomer at Observatoire de Paris, expressed surprise at the discovery, emphasizing Mimas' unlikely candidacy for harboring an ocean. However, meticulous analysis of Cassini data revealed compelling evidence supporting this conclusion.
"It's quite a surprise," said 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."
The findings regarding Mimas' hidden ocean have been lauded by fellow researchers as "inspiring," though they also recognize the relevance of previous hypotheses concerning Mimas' distinctive orbit.
The ocean is "remarkably young," according to another study co-author Dr. Nick Cooper, honorary research fellow in the astronomy unit of the School of Physical and Chemical Sciences at Queen Mary University of London.
Believed to be between 5 to 15 million years old, the ocean's relatively recent formation suggests dynamic processes at play within the moon. Tidal forces exerted by Saturn likely played a crucial role, heating Mimas' core and initiating the formation of the ocean.
Despite these groundbreaking findings, questions remain about the ocean's potential for supporting life. While its existence raises tantalizing possibilities, the ocean's youth may limit the opportunity for life to emerge. Nonetheless, scientists remain hopeful about the prospect of exploring Mimas further.
"Mimas was probably the most unlikely place to look for a global ocean - and liquid water more generally," Lainey stated in an email, according to AP News. "So that looks like a potential habitable world. But nobody knows how much time is needed for life to arise."
Furthermore, the astronomer noted that the discovery of Mimas' ocean may indicate the potential presence of liquid water in other various places. She added that there are already significant candidates for global oceans, including moons such as Callisto, Dione, and Triton.
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