NASA: Saturn's Moon Enceladus Harbors Underground Ocean of Liquid Water
Posted on April 3, 2014
NASA announced today that Saturn's moon Enceladus harbors an underground ocean of liquid water. Astronomers used gravity measurements from NASA's Cassini spacecraft and Deep Space Network to determine that there is a large interior ocean underneath the moon's ice shelf. NASA also says this liquid ocean could be a potential home to extraterrestrial microbes.
Sami Asmar of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., co-author of a paper published in Science, says in the announcement, "The way we deduce gravity variations is a concept in physics called the Doppler Effect, the same principle used with a speed-measuring radar gun. 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. 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."
NASA says the gravity measurements indicate the ocean is about 6 miles (10 kilometers deep) and 19 to 25 miles (30 to 40 kilometers thick). Newsweek reports the scientists say the moon's ocean is the size of Lake Superior. NASA says the moon also has jets of water vapor and ice gushing from its south pole. Scientists are not yet certain if the underground ocean is supplying the water plume spraying out of fractures in the south pole, but they think it is a real possibility.
Luciano Iess of Sapienza University of Rome, lead author of the paper, says, "The Cassini gravity measurements show a negative gravity anomaly at the south pole that however is not as large as expected from the deep depression detected by the onboard camera. Hence the conclusion that there must be a denser material at depth that compensates the missing mass: very likely liquid water, which is seven percent denser than ice. The magnitude of the anomaly gave us the size of the water reservoir."
Linda Spilker, Cassini's project scientist at JPL, says, "Material from Enceladus' south polar jets contains salty water and organic molecules, the basic chemical ingredients for life. 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."
The paper, "The Gravity Field and Interior Structure of Enceladus," can be found here in the journal Science.