Cape Canaveral: An ocean of liquid water, potentially capable of sustaining simple life, is sloshing around inside Saturn’s ice-encrusted moon Enceladus.
Published on: 4/5/2014IST
Saturn’s ice-encrusted moon hides an ocean
Water body in Saturn’s moon Enceladus believed to be at least as big as
Lake Superior
4/5/2014 | | Permalink
- Image Credit: AP
- This illustration provided by NASA and based on Cassini spacecraft measurements shows the possible interior of Saturn's moon Enceladus - an icy outer shell and a low density, rocky core with a regional water ocean sandwiched in between the two at southern latitudes. Plumes of water vapor and ice, first detected in 2005, are depicted in the south polar region. Scientists have uncovered a vast ocean beneath the icy surface of the moon, they announced Thursday. Italian and American researchers made the discovery using Cassini, a NASA-European spacecraft still exploring Saturn and its rings 17 years after its launch from Cape Canaveral.
US and Italian scientists used instruments on Nasa’s Cassini spacecraft, which has been orbiting Saturn since 2004, to deduce that the southern hemisphere of Enceladus contains an ocean perhaps 10km deep beneath 30km to 40km of ice. Situated some 1.3 billion km away in the outer solar system, icy Enceladus seems an unlikely place for liquid water.
But gravity measurements taken by NASA’s Saturn-orbiting Cassini spacecraft indicate the moon contains an underground ocean in its southern hemisphere. The ocean is believed to be at least as big as Lake Superior, according to research published this week in the journal Science.
The water, sitting on an ocean floor consisting of silicate rocks, is kept liquid by tidal heating as Enceladus moves around Saturn.
“The contact between water and silicates makes this environment suitable for rich and complex chemical reactions that, in the presence of an energy source, might create prebiotic conditions” favourable for life, said Luciano Iess of Sapienza University in Rome, the project leader.
Enceladus, a small moon just 500km in diameter, joins Europa, a larger moon of Jupiter that also has an ice-bound ocean, and Ganymede and Saturn’s large moon Titan on scientists’ list of bodies in the solar system that could sustain microbial life.
No one knew there was liquid water on Enceladus until 2005 when Cassini sent pictures back to Earth showing geysers spewing water vapour and ice from fractures in its icy surface, known as tiger stripes. But that observation was also explicable by local melting of the ice rather than the presence of a deep ocean.
Confirmation of the ocean comes from geophysical measurements of its internal structure during three subsequent fly-bys of Enceladus. Variations in gravitational field produced small variations in Cassini’s velocity as it skimmed past the moon.
4/5/2014 | | Permalink