An SwRI scientist has discovered that Saturn’s small moon Mimas (left) likely has something in common with its larger neighbor Enceladus: an internal ocean beneath a thick icy surface. Image Credit: NASA / JPL-Caltech / Space Science Institute.

Researchers Find Evidence of Subterranean Ocean On Saturn’s “Death Star” Moon Mimas

A group of researchers has discovered that one of Saturn's moons, Mimas—the mystery satellite that eerily resembles the "Death Star" from the Star Wars franchise—contains an underground ocean that had remained hidden to this date.


Mimas, the smallest and innermost of Saturn’s major satellites and home to a large crater that resembles the Death Star from Star Wars, exhibits compelling evidence that it has an internal liquid ocean.

According to the Southwest Research Institute reports, the Cassini mission identified a curious libration, or wobble, in the moon’s rotation, often pointing to a geologically active body capable of harboring an internal ocean.


“If Mimas has an ocean, it represents a new class of small, ‘stealth’ ocean worlds with surfaces that do not betray the ocean’s existence,” explained SwRI’s Dr. Alyssa Rhoden, a specialist in the geophysics of icy satellites, particularly those containing oceans, and the evolution of giant planet satellites systems.

Europa, Titan, Enceladus and now Mimas and Pluto?

Over the past few decades, significant progress has been achieved in the exploration of our solar system, its planets, and particularly the moons around gas giants such as Jupiter or Saturn.

Explorations of our cosmic neighborhood–thanks to various robotic missions–have helped us understand that our solar system is rich in worlds that harbor oceans beneath massive layers of rock and ice. The most famous of these worlds are the icy moons of Saturn and Jupiter; Europa, Titan, and Enceladus, but evidence of a subterranean ocean has even been uncovered in extremely distant places in our solar system, like Pluto.


These worlds are very different from our planet because worlds like Earth that house surface oceans must reside within a narrow range of distances from their stars to maintain the temperatures that are necessary to support liquid oceans on their surface.

Interior water ocean worlds (IWOWs)–like Europa, Titan, Enceladus, and even Pluto— however, can exist over a much broader range of distances, which significantly extends the number of habitable worlds likely to exist across our galaxy.

An ocean world covered by thick layers of Ice

“Because the surface of Mimas is heavily cratered, we thought it was just a frozen block of ice,” Rhoden explained.

“IWOWs, such as Enceladus and Europa, tend to be fractured and show other signs of geologic activity. As it turns out, Mimas’ surface was tricking us, and our new understanding has greatly expanded the definition of a potentially habitable world in our solar system and beyond.”

Which less than 123 miles (198 kilometers) in mean radius, crater-covered moon Mimas is the smallest and innermost of Saturn’s major satellites.


Based on various models, the researchers also concluded that if Mimas does indeed harbor an internal ocean, it is likely covered by a steady-state ice shell between 14 to 20 miles thick.

Read more at SwRI

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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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