Evidence of Watery Ocean Found Beneath Ice on Saturn's Tiny Moon Enceladus
Deep beneath the icy shell of Saturn's tiny moon Enceladus, scientists have found evidence of an underground ocean of liquid water.
Writing in the journal Science, the team from NASA's Cassini mission and the Deep Space Network presents data that provide the first geophyscal measurements of the internal structure of Enceladus, revealing the moon to have properties to be consistent with theories that it harbors an underground ocean.
To make the measurements, scientists took advantage the Doppler Effect created as the Cassini spacecraft flies over the moon.
"As the spacecraft flies by Enceladus, its velocity is perturbed by an amount that depends on variations in the gravity field that we're trying to measure," Sami Asmar of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., said in a statement. "We see the change in velocity as a change in radio frequency, received at our ground stations here all the way across the solar system."
The ice shell of Enceladus is up to 25 miles thick, NASA reported. But the data collected by Cassini suggest that the ocean beneath the ice could be as many as 6 miles deep.
Earlier observation of Enceladus revealed the moon had geysers of water gushing out from regions in its south pole. If the moon has an underground ocean, if provides a link to the origins of the phenomenon. Additionally, an anomaly in the moon's gravitational pull in ts southern hemisphere suggests that something very dense lies beneath the ice.
"Then you say, 'Aha, there must be compensation,' " study author David J. Stevenson, a professor of planetary science at the California Institute of Technology, told The New York Times. "Something more dense under the ice. The natural candidate is water."
"What we've done is put forth a strong case for an ocean," he said.
The scientist also suggest that evidence of an underground ocean should support including Enceladus on the short list of places in our solar system that could likely host microbial life.
"Material from Enceladus' south polar jets contains salty water and organic molecules, the basic chemical ingredients for life," said Linda Spilker, Cassini's project scientist at JPL. "Their discovery expanded our view of the 'habitable zone' within our solar system and in planetary systems of other stars. This new validation that an ocean of water underlies the jets furthers understanding about this intriguing environment."