A new study suggests that Saturn's largest moon, Titan, has a thick, rigid crust of ice, and is apparently far stronger than researchers previously thought.
"Already things on Titan were hard to explain. This makes it even worse," says study coauthor Doug Hemingway, a planetary geophysicist at the University of California, Santa Cruz, according to Science News. "It deepens the mystery of a very strange body."
NASA's Cassini probe, which has orbited Saturn since 2004, has peered through Titan's orange haze to discover methane and other hydrocarbons raining down to fill vast lakes as well as freezing to form soaring dunes. Cassini also has collected evidence for an ocean of liquid water that was separated from the surface by an icy crust. Scientists say that these surprising new findings add to hints that Titan possesses an extraordinarily bizarre interior.
Past research suggested Titan has an ocean hidden under its outer icy shell 30 to 120 miles thick, which investigators hope to explore in order to find alien life on Titan.
To learn more about Titan's icy shell, Hemingway analyzed the Cassini probe's scans of Titan's gravity field. The strength of the gravitational pull any point on a surface exerts depends on the amount of mass underneath it. Essentially, the stronger the pull, the more the mass.
The researchers then compared these gravity results with the structure of Titan's surface. What the investigators discovered shocked them. The regions of high elevation on Titan had the weakest gravitational pull.
"It was very surprising to see that," Hemingway told SPACE.com. "We assumed at first that we got things wrong, that we were seeing the data backwards, but after we ran out of options to make that finding go away, we came up with a model that explains these observations."
To explain these gravity anomalies, Hemingway said to imagine mountains on Titan having roots. "It's like how most of an iceberg actually lies submerged underwater," he said. "If that root is really big, bigger than normal, it would displace water underneath it."