Saturn's Moon Dione Hiding a Watery Secret Beneath Icy Exterior
A new study revealed that Saturn's moon Dione, like Titus and Enceladus, is hiding an ocean of liquid water deep within its icy surface.
The study, published in the journal Geophysical Research Letters, suggests that the ocean between the crust and core of Dione survived for the whole history of the moon, making it a long-lived habitual zone for microbial life.
"The contact between the ocean and the rocky core is crucial" explained co-author of the study Attilio Rivoldini, of the Royal Observatory of Belgium in Brussels, in a statement. "Rock-water interactions provide key nutrients and a source of energy, both being essential ingredients for life."
For the study, the researchers modeled the icy shells of Dione as global icebergs immersed in water, where each surface ice peak is supported by a large underwater keel. Using this model, the researchers were able to explain the gravity data from the recent flybys of NASA's Cassini spacecraft.
Based on the data from Cassini, the researchers believe that the Dione's crust is floating on an ocean located 100 kilometers below the surface. The ocean is about tens of kilometers deep and surrounds a large rocky core. Unlike its neighbor Enceladus, Dione seems to be quiet at the moment.
Astronomers have observed violent geysers blasting ice water and other material near the south pole of Enceladus. The new study suggests that these eruptions occur because Enceladus' ocean is much closer to the surface.
If confirmed, Dione will be third Saturn moon to be considered as ocean world, joining the ranks of the more famous Titan and Enceladus. Astronomers are also considering the possibility that Jupiter's Europa, Callisto and Ganymede also have buried oceans.
The researchers noted that their predictions can only be tested by a future orbiter lurking around the Saturn's moon. This is due to the fact that the ocean in Dione is well beneath its surface and the moon is not as kind enough as Enceladus, which spew water samples in the space.