Titan, Saturn's biggest moon, could have an ocean under its ice shell. Astronomers from Nasa, Cornell University and Sapienza University have found clues to an underground ocean beneath Titan's ice crust. They were able to determine the moon's internal structure by measuring variations in the gravitational pull of Titan using data received from Nasa's Cassini spacecraft.
"We were making ultrasensitive measurements, and thankfully Cassini and the Nasa's Deep Space Network (DSN) were able to maintain a very stable link," said Sami Asmar, astronomer at Nasa's Jet Propulsion Laboratory in Pasadena, in a statement.
During the study, the astronomers witnessed a large amount of squeezing and stretching in Titan, as it orbited Saturn. They claimed that if Titan were composed entirely of stiff rock, the gravitational attraction of Saturn would cause bulges, or solid "tides," on the moon only 3 feet (1 metre) in height, but the spacecraft data shows Saturn creates solid tides approximately 30 feet (10 metres) in height, which suggests Titan is not made entirely of solid rocky material.
"Cassini's detection of large tides on Titan leads to the almost inescapable conclusion that there is a hidden ocean at depth," said Luciano Iess, astronomer at the Sapienza University, in a statement. "The search for water is an important goal in solar system exploration, and now we've spotted another place where it is abundant."
At the time of Titan's orbit, astronomers also found that the moon gets elongated when it is closer to Saturn, due to the gravitational pull of Saturn. When Titan was farther from Saturn, it became less elongated and more round. This clearly shows that there is a chance of water existing beneath the surface of the planet
"The presence of a liquid water layer in Titan is important because we want to understand how methane is stored in Titan's interior and how it may outgas to the surface," said Jonathan Lunine, astronomer at Cornell University, in a statement. "This is important because everything that is unique about Titan derives from the presence of abundant methane, yet the methane in the atmosphere is unstable and will be destroyed on geologically short timescales."