There's little doubt now that the Saturn moon Enceladus hides a vast, liquid ocean beneath its icy surface.
Massive plumes of water vapor discovered by Cassini in 2005 sparked speculation of sub-surface liquid water within the tiny moon. Later, fly-bys found that the massive geysers - whose jet steams supply the material for Saturn's outer-most ring - contain traces of sodium — believed to be the signature of a large body of liquid water with long periods of contact to minerals deep inside Enceladus.
Now, a team of scientists from University College London's Mullard Space Science Laboratory say data from the intrepid probe's plasma spectrometer has found negatively charged water molecules in the jet spray. On Earth's surface, such ions are present where liquid water is in motion, such as waterfalls or ocean waves.
"While it's no surprise that there is water there, these short-lived ions are extra evidence for sub-surface water," said Andrew Coates of Mullard Space Science Lab in a statement. "And where there's water, carbon and energy, some of the major ingredients for life are present."
The findings are based on data taken in a Cassini plume fly-through conducted in 2008 and reported in the trade journal Icarus.
Last week, NASA announced it would once again extend the probe's mission to explore Saturn and its moons to 2017. The project was originally scheduled to end in 2008, but the mission received a 27-month reprieve to September 2010.
"This is a mission that never stops providing us surprising scientific results and showing us eye popping new vistas," said Jim Green, director of NASA's planetary science division in a statement. "The historic traveler's stunning discoveries and images have revolutionized our knowledge of Saturn and its moons."
NASA said the latest extension will allow scientists to continue to ogle and observe Saturn's rings and the magnetic bubble around the planet.
Thus far, Cassini has beamed home more than 210,000 images, made 125 revolutions around Saturn, 67 flybys of Titan, and eight close flybys of Enceladus. ®