“the final ingredient, liquid water..”

The Royal Observatory at Greenwich may have an exhibition of images from the Cassini-Huygens mission, but Cassini itself is continuing to observe in and around Saturn. The discovery of sodium salts in the water-ice jets of Enceladus is being interpreted as evidence of a reservoir of liquid water beneath its surface.

“Our measurements imply that besides table salt, the grains also contain carbonates like soda. Both components are in concentrations that match the predicted composition of an Enceladus ocean,” Postberg said. “The carbonates also provide a slightly alkaline pH value. If the liquid source is an ocean, it could provide a suitable environment on Enceladus for the formation of life precursors when coupled with the heat measured near the moon’s south pole and the organic compounds found within the plumes.”

And here’s the associated Jet Propulsion Laboratory video. Adds BBC report. And Some of the older links don’t work due to a redesign of the Cassini [JPL] website. Here’s a key press release from March 2008.