Titan is surrounded by an ice shell, but below the surface, scientists believe there is an ocean of liquid water that could be just as salty as the Dead Sea.
Cassini collected gravity and topography data during its flybys of Titan over the past 10 years, allowing researchers to create a new model of the structure of the moon's outer icy shell.
The new model suggests that the thickness of the icy crust varies across the moon's surface. This means that the ocean underneath is probably in the process of freezing, too. If the ocean is freezing, it would decrease the chances that the ocean could support life, since freezing would limit the exchange of materials between the water and the surface, researchers said.
The new data could also provide some insight into Titan's unique atmosphere, which is consistently around 5 percent methane. It is still a mystery how Titan maintains methane in its atmosphere since sunlight quickly breaks up the gas.
Scientists believe some kind of natural process must be cycling the methane into the atmosphere; from there, it falls back down to the surface as methane rain, similar to the water cycle on Earth. Since Titan's surface is mostly frozen, researchers think any methane rising into the atmosphere must be coming from a few scattered unfrozen "hot spots."