Iess and coworkers detected in Cassini data the signature of the periodic tidal stresses within Titan. The large response to the tidal field requires that Titan’s interior is deformable over time scales of the orbital period, in a way that is consistent with a global ocean at depth.
This findings makes Titan the closest planet within the solar system to what primeval Earth might have been and an unmatched opportunity to study origin of life scenario by the Cassini space probe.
Iess L, Jacobson RA, Ducci M, Stevenson DJ, Lunine JI, Armstrong JW, Asmar SW, Racioppa P, Rappaport NJ, Tortora P.
The Tides of Titan.
Science. 2012 Jun 28.