Reanalysis of Cassini Data Indicates Titan Likely Has Slushy Interior, Not a Global Ocean

A reanalysis of radio tracking data from NASA’s Cassini mission suggests Saturn’s moon Titan may not host a single global ocean beneath its surface but instead has a layered interior of ice, slush and small pockets of warm water near its rocky core. The new study, led by researchers at NASA’s Jet Propulsion Laboratory and published in Nature, applied a novel processing technique to Doppler radio-frequency data collected during Cassini’s 10 close approaches to Titan.

Scientists use Doppler shifts in spacecraft radio signals to map a body’s gravity field and detect shape changes caused by tidal flexing as a moon moves in its planet’s gravitational pull. Earlier analyses interpreted Titan’s pronounced flexing as evidence for a global liquid layer.

By reducing noise in the Doppler data, the team detected a signature of strong energy dissipation deep inside Titan. The authors interpret this as frictional heating from slushy layers of mixed ice and water beneath a thick solid-ice shell, rather than a homogeneous liquid ocean. Lead author Flavio Petricca, a JPL postdoctoral researcher, said the slushy interior still allows Titan to bulge and compress with Saturn’s tides but removes heat that would otherwise melt the ice into a global ocean.

Key Topics

Science, Titan, Cassini, Jet Propulsion Laboratory, Doppler Data, Tidal Flexing