Photo: Cassini spacecraft
When NASA’s Cassini spacecraft flew over the frozen ice cap of Enceladus, one of Saturn’s 60 moons, and encountered water vapor issuing from its south pole, scientists began suspecting the existence of an ocean, according to an article in Science magazine.
And where there is water, scientists say, there could be, or has been, life.
Scientists believe the data colllected by Cassini in its flybys around Enceladus and the consequent studies of gravity on that moon indicate the presence of water below the outer layer of ice on the satellite, which measures a mere 500 kilometers (310 miles) in diameter.
Analysis of the data collected and transmitted by Cassini from more than 1.2 billion kilometers (745 million miles) was done by scientists at Sapienza University in Rome, the California Institute of Technology, Cornell University in New York and the University of Bologna in Italy.
“What we’ve done is put forth a strong case for an ocean,” said David J. Stevenson, a professor of planetary science at the California Institute of Technology and an author of the Science paper.
The Cassini spacecraft has been navigating among Saturn’s moons for the past 10 years and its observations and measurements of gravity indicate, the scientists say, that Enceladus could have an ocean beneath its 30-to-40-kilometer- (19-to-25-mile-) thick ice cap.
Researchers particularly analyzed the striking asymmetry that exists between the northern and southern hemispheres of Enceladus, and that according to the data, the southern region does not have a sufficient mass on its surface to explain the gravity of the hemisphere.
“Then you say, ‘A-ha, there must be compensation,’ ” Dr. Stevenson said. “Something more dense under the ice. The natural candidate is water.”