Saturn's moon Mimas could be a habitable ocean world

Life on Saturn's moon?

NASA wants to find out 0:33

(CNN) --

Saturn's innermost moon, which resembles the "Death Star" from "Star Wars," could be a "stealth" ocean world, according to new research.

Mimas, which is the smallest and closest to Saturn of the planet's 82 moons, could contain an internal liquid ocean.

"If Mimas does have an ocean, it represents a new class of small 'stealth' ocean worlds with surfaces that don't give away the ocean's existence," said study author Alyssa Rhoden, a scientist at the Southwest Research Institute in Boulder, Colorado, in a statement.

The study was published last week in the academic journal

.

Mimas was discovered in 1789 by the English astronomer William Herschel as a small dot near Saturn.

The Voyager probes took images of the small moon in 1980, and NASA's Cassini mission flew by it while studying Saturn between 2004 and 2017.

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The moon is only 186,000 kilometers from Saturn and takes just over 22 hours to complete one orbit around the planet.

Mimas is covered in craters, but the largest is 130 kilometers across and gives the moon its distinctive "Death Star" appearance.

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Mimas has long intrigued scientists because it is likely to be composed almost entirely of ice.

Craters scattered across the moon suggest that its surface has been frozen for a long time.

However, before the Cassini mission ended in 2017, it detected a wobble in the moon's rotation that suggested Mimas might contain an underground ocean.

Our solar system is home to multiple ocean worlds, or moons where oceans exist under thick shells of ice, such as Jupiter's moon Europa and Saturn's moons Titan and Enceladus.

These differ from Earth, which is at the right distance from the Sun to include oceans of liquid water on its surface.

Worlds with inland water oceans (IWOWs) are much farther from the Sun. But they could still harbor life in their oceans.

"Because the surface of Mimas is so heavily cratered, we thought it was just a frozen block of ice," said Rhoden, who is also one of the leaders of the Ocean Worlds Research Coordination Network at the POT.

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"IWOWs, like Enceladus and Europa, tend to be fractured and show other signs of geological activity. It turns out that Mimas's surface was playing tricks on us, and our new information has greatly expanded the definition of a potentially habitable world in our solar system and beyond".

Mimas is tidally locked in its orbit around Saturn, meaning the same side of the moon always faces the planet, like our moon when it orbits Earth.

The researchers believe that a phenomenon called tidal heating allows the subsurface ocean to exist on Mimas.

Saturn's small moon Mimas (left) probably has something in common with its larger neighbor Enceladus (right): an internal ocean beneath a thick icy surface.

Tidal heating causes an internal temperature rise in a moon due to its gravitational relationship with a planet.

To recreate the wobble that Cassini detected in Mimas's rotation, the researchers used models to show that tidal heating on the small moon is enough to keep an ocean under 22.5 to 32 kilometers of ice. of thickness.

This finding could be useful for future spacecraft to study ocean worlds in our solar system.

But it also shows that Mimas and Saturn's other moons may be worth looking at more of in the future.

Future spacecraft could confirm that Mimas is indeed one of these worlds with interior water oceans.

"Assessing Mimas's status as an oceanic moon would serve as a benchmark for models of its formation and evolution," Rhoden said.

"This would help us better understand Saturn's rings and medium-sized moons, as well as the prevalence of potentially habitable oceanic moons, especially on Uranus. Mimas is a compelling target for further investigation."

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