Recent data from the Cassini probe that is in the lunar system of Saturn has spotted water vapour spewing from the moon Enceladus' icy surface. This just adds to more evidence of a sub-surface ocean on that moon.
The probe spotted negatively charged water molecules in the moon's atmosphere. On earth, such ions are seen where liquid water-such as water falls, or ocean waves crashing against the shore is seen.
Quoting that article: "We see water molecules that have additional electrons added," explained Andrew Coates from University College London's Mullard Space Science Laboratory. "There are two ways they could be added - from the ambient plasma environment, or it could be to do with friction as these water clusters come out of the jets, like rubbing a balloon and sticking it on the ceiling," he told BBC News.
Cassini has also detected sodium in these plumes. This is a sign of dissolved salts in any mass of liquid water that has been in contact with rock for a long epriod of time.
Picture are from the BBC article.
Ref. BBC, February 8, 2010. "Cassini detection adds to Enceladus liquid water story" by Jonathan Amos. (http://news.bbc.co.uk/2/hi/science/nature/8495663.stm).