Saturn’s Moon Dione Has A Subsurface Ocean

An entire ocean lies beneath the surface of Saturn’s moon, Dione, says a paper published in the journal Geophysical Research Letters.

Saturn and its moon, Dione.
Saturn and its moon, Dione.

Dione is one of the many moons of Saturn. Its sisters Titan and Enceladus have already been shown to hold subsurface oceans in their icy crusts. Dione is no different, says a new study conducted by scientists from the Royal Observatory of Belgium.

Diameter comparison of Saturn's moon Dione, the Moon and Earth. Photo credits: Earth image: NASA; Lunar image: Gregory H. Revera; Moon Dione image: ASA/JPL/Space Science Institute. Via Wikimedia Commons.
Diameter comparison of Saturn’s moon Dione, the Moon and Earth.
Photo credits: Earth image: NASA; Lunar image: Gregory H. Revera; Moon Dione image: ASA/JPL/Space Science Institute.
Via Wikimedia Commons.

The team used gravity data obtained from the Cassini mission to the planet. According to their research, an ocean is found at around 100 kilometres beneath Dione’s crust. The ocean is, in turn, above a massive rocky core. Dione would, thus, have a deep ocean between its crust and core.

The new findings suggest that Dione is very similar to its neighbour, the moon Enceladus which also bears an underwater ocean. Also, both oceans apparently experience enormous back-and-forth oscillations called libration.

“Like Enceladus, Dione librates but below the detection level of Cassini,” said Antony Trinh, one of the authors of the new study. “A future orbiter hopping around Saturn’s moons could test this prediction.”

One difference between the two, though, is that Enceladus’ ocean is closer to the surface. This allows Enceladus to release water vapour into space while Dione cannot do the same because of its ocean being too deep.

Now, what makes this discovery exciting?! The authors of the new paper hypothesise that Dione’s ocean might constitute a habitable area for microbes as it has probably been there for all the moon’s existence. The closeness of the ocean to the core might have allowed for the concoction of life’s essentials.

“The contact between the ocean and the rocky core is crucial,” said Attilio Rivoldini, co-author of the study. “Rock-water interactions provide key nutrients and a source of energy, both being essential ingredients for life.”

Subsurface oceans are no more of a surprise nowadays. Jupiter has already been ascribed with its own secret oceans. Other planets like Pluto might also be similar in this aspect, say the authors. Furthermore, more missions will be elaborated to study the systems of planets Uranus and Neptune.

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