Saturn's moon Dione may have an ocean, according to new data from the Cassini mission to Saturn.

Two of the planet's other moons - Titan and Enceladus - have already been revealed to harbour global oceans under their icy crusts.

New gravity data from recent Cassini flybys of the giant planet suggest that Dione's crust floats on an ocean 62 miles (100km) below the surface, according to researchers at the Royal Observatory of Belgium.

Dione (near) is thought to harbour a global ocean under its icy crust like fellow moon Enceladus (far), though much further under the surface

OCEAN ON EUROPA Hubble spotted giant plumes of water 125 miles high erupting from the surface of Jupiter's moon Europa, raising hopes it could hold life in a vast underground ocean engulfing the moon, NASA revealed last week. The new images 'indicate a global saline liquid water ocean engulfs the moon at the present time hidden under miles of ice,' NASA said. It increases the possibility that missions to Europa may be able to sample Europa's ocean without having to drill through miles of ice. Advertisement

The galactic ocean is thought to be tens of kilometers deep, surrounding the moon's rocky core.

The Cassini spacecraft, operated by Nasa, first launched in 1997 and first reached Saturn in 2004.

Dione is very similar to its smaller but more well-known sibling moon Enceladus, says the study.

Encaladus has previously been shown to spurt massive jets of water vapour into space from its south polar region.

While Dione is currently quiet, the researchers suggest that its surface shows signs of a more active past.

Previous modelling based on the available data had predicted that Dione had no ocean at all.

The new study says that Enceladus' ocean is much closer to the surface than that of Dione.

The findings back up a Cassini's discovery last year that Enceladus experiences large back-and-forth oscillations - known as libration - during its orbit.

Enceladus' libration would be much smaller if its crust was thicker, says the study, while Dione hides a deep ocean between its crust and core.

'Like Enceladus, Dione librates but below the detection level of Cassini,' said Antony Trinh, co-author of the new study.

'A future orbiter hopping around Saturn's moons could test this prediction.'

Dione could potentially offer a habitable environment for microbial life, suggest the researchers.

This illustration shows the interior of Saturn's moon Enceladus with a global liquid water ocean between its rocky core and icy crust

'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.'

While Dione's ocean is too deep to be easy accessible, both Enceladus and Jupiter's moon Europa regularly eject water into space, which can be gathered by passing space probes for analysis.

'Ocean worlds' - moons or planet with subsurface oceans - have been discovered around Jupiter, Saturn and Pluto, but the researchers say that there may be more.

They say that these could be identified using a similar modelling approach with data from space probes.

'Future missions will visit Jupiter's moons, but we should also explore Uranus' and Neptune's systems', said Mikael Beuthe.