As new data from the Cassini mission to Saturn floats in scientists determined that one of its moons, Dione, will be entering the subsurface oceans club as gathered data shows evidence of water under the moon’s crust.
Previous studies have already demonstrated the existence of global oceans beneath the icy exterior of Saturn’s satellites, Titan and Enceladus, and based on the new data Dione appears to be following in their lead.
As the Royal Observatory of Belgium scientists have observed, recent Cassini flyby data has shown gravity information that can only be justified by an under the crust planetary ocean. The water would be located at somewhere around 100 kilometers bellow the moon’s surface and would be surrounding a rocky planet core. Very similar to its much smaller neighbor, Enceladus, who is famous for jetting water vapor jets into space, Dione’s now calm broken surface seems to bear the marks of a past equally as tumultuous.
Last year, Cassini gathered data revealed Enceladus’s large back-and-forth oscillations, or libration, registered during its orbit. The findings seem to go well with the generally agreed upon data that its underground ocean is much closer to the surface, especially near the moon’s south pole where geysers are capable of erupting through the crust surface. This can be demonstrated by the libration speed, which would be smaller if the planet’s crust was thicker.
Just as Enceladus, Dione is also thought to be librating, but its speed is bellow Cassini’s radar possibilities so the theory could be proved right sometimes in the future when an orbiter could go round Saturn’s satellites.
Although Enceladus and Europe are frugal water sources for scientists to study, as both spurt water into space, Dione’s ocean appears to be too far under the surface to be easily accessed and studied with our current technology. Nonetheless, scientists have come to believe that Dione’s subsurface waters have probably existed throughout the moon’s whole history and maybe could have even offered a microbial habitable space. The microbial habitat could be made possible if the water containing it would be in direct contact with the rocky core it surrounds.
With advances in the possibility to study the shape and gravity fields of planets and satellites alike, new discoveries are expected as Uranus and Neptune future missions are in the making and current missions are revealing more and more information.
The subsurface oceans club includes, for the moment, the three satellites orbiting Jupiter, three of Saturn’s explored moons, possibly even Pluto, and each new space mission is expected to provide further data and members.
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