WASHINGTON, Sept. 15 (UPI) -- New data analysis from NASA's Cassini mission confirms the presence of a global ocean beneath the icy crust of Saturn's moon Enceladus.
Researchers have long theorized that Enceladus' outer layer of ice surrounds an inner layer of liquid. Recent samples collected by the Cassini probe even picked up the presence of water vapor near the moon's southern pole.
But now the source of that water is a scientific certainty.
In analyzing the moon's slight wobble, scientists working on NASA's Cassini mission determined the moon's oscillation can only be properly modeled if its ice isn't frozen all the way to the core.
The presence of a global ocean explains both the moon's unique movements and the fine spray of water vapor escaping from cracks in its icy shell.
"If the surface and core were rigidly connected, the core would provide so much dead weight the wobble would be far smaller than we observe it to be," Matthew Tiscareno, a researcher at the SETI Institute and a member of the Cassini science team, explained in a press release. "This proves that there must be a global layer of liquid separating the surface from the core."
Tiscareno is co-author of a new paper on the discovery of Enceladus' ocean. The paper was recently published in the journal Icarus.
"This was a hard problem that required years of observations, and calculations involving a diverse collection of disciplines, but we are confident we finally got it right," said Peter Thomas, the study's lead author.
Scientists still aren't sure what is preventing the moon's innards from freezing. Some researchers have suggested the thermal energy from friction generated by the push and pull of Saturn's gravity is enough to keep the moon's insides liquified. Thomas and his colleagues say further research is needed to more thoroughly test such an explanation.