NASA's Cassini spacecraft has discovered evidence that points to the existence of an underground ocean of water and ammonia on Saturn's moon Titan.
"We believe that about 100 kilometers (62 miles) beneath the ice and organic-rich surface is an internal ocean of liquid water mixed with ammonia," said Bryan Stiles of NASA's Jet Propulsion Laboratory in Pasadena, California.

If the findings turn out to be true, this will be the fourth such moon in our solar system found to have some form of water on it. Currently only three other moons, all from Jupiter, have been found to have known water sources. Ganymede, Callisto and Europa are so far the only known moons with a water source.
Members of the mission's science team used Cassini's Synthetic Aperture Radar to collect imaging data during 19 separate passes over Titan between October 2005 and May 2007. The radar can see through Titan's dense, methane-rich atmospheric haze, detailing never-before-seen surface features and establishing their locations on the moon's surface.

Using data from the radar's early observations, the scientists and radar engineers established the locations of 50 unique landmarks on Titan's surface. They then searched for these same lakes, canyons and mountains in the reams of data returned by Cassini in its later flybys of Titan. They found prominent surface features had shifted from their expected positions by up to 30 kilometers (19 miles). A systematic displacement of surface features would be difficult to explain unless the moon's icy crust was decoupled from its core by an internal ocean, making it easier for the crust to move.

Cassini scientists will not have long to wait before another go at Titan. On March 25, just prior to its closest approach at an altitude of 1,000 kilometers (620 miles), Cassini will employ its Ion and Neutral Mass Spectrometer to examine Titan's upper atmosphere. Immediately after closest approach, the spacecraft's Visual and Infrared Mapping Spectrometer will capture high-resolution images of Titan's southeast quadrant.

The study of Titan is a major goal of the Cassini-Huygens mission because it may preserve, in deep-freeze, many of the chemical compounds that preceded life on Earth. Titan is the only moon in the solar system that possesses a dense atmosphere. The moon's atmosphere is 1.5 times denser than Earth's. Titan is the largest of Saturn's moons, bigger than the planet Mercury.

A very close flyby of Saturns's icy moon Enceladus occurred Wed., March 12, 2008.

The fate of the $3.5 Billion mission was in the balance as the bus-sized spacecraft swooped to just 50 km above the surface of Enceladus to sample the frozen spray issuing from liquid water gysers. Water gysers were unexpected because everything else on Enceladus is very much colder than liquid water.

The Cassini-Huygens space probe is an international mission involving the cooperative efforts of NASA, the European Space Agency and the Italian Space Agency.

The probe, launched in 1997, has orbited Saturn since 2004 but has never before flown so close to a moon.

Space probe Cassini performed a close flyby of Saturn's icy moon Enceladus on Wednesday. The fate of the $3.5 billion mission was in the balance as the bus-sized spacecraft swooped to just 50 km (30 mi) above the surface of Enceladus to sample the frozen spray issuing from geysers on the the moon's surface. The "water" spraying from these geysers is in the form of dust-sized, frozen water particles, which are ejected into space by gaseous water vapors that build up pressure deep within icy fissures on Enceladus.

Cassini's cosmic dust analyzer was unavailable due to a glitch in the updated software that was supposed to provide an increased hit count of the geyser dust particles. However, dust samples were collected before and after the closest approach and the mass spectrometer functioned though out the flyby, providing useful data which is now being analyzed.
Mission controllers will have a chance to capture more geyser dust on October 9, 2008 when they may choose to steer Cassini even closer to the surface of Enceladus.

Tidal flexing of this moon due to the gravitational proximity of its host planet, Saturn, continually heaves and cracks the icy surface. This suggests that Enceladus may have a squishy, liquid-water ocean beneath an icy crust. Deep, parallel fissures in the ice crust, dubbed the "Tiger Stripes", measure warmer than uncracked, stationary surfaces nearby. Friction of these massive, moving plates of ice is thought to provide the heat responsible for the pressurized geysers of sublimated water and ice dust. The presence of these geysers amounts to more empirical evidence of a large, liquid water ocean below the surface of Enceladus.

The Cassini-Huygens space probe is an international mission involving the cooperative efforts of NASA, the European Space Agency, and the Italian Space Agency. Launched in 1997, Cassini has orbited Saturn since 2004 but has never before flown so close to a moon. On 14 January 2005, the Huygens lander successfully explored the atmosphere and surface conditions of Saturn's biggest moon, Titan.