A few weeks ago, it was Saturn’s moon Titan that was grabbing headlines when researchers described a form of methane based life that could, theoretically, exist there. This week the attention shifts to Saturn’s frozen moon Enceladus, where evidence of geysers could point to a habitat warm enough for life.

In 2005, ice and water vapor were seen erupting from fractures of Saturn’s icy moon Enceladus. Since that time, researchers have worked to understand the process that would cause such an eruption and the secrets of what is going on beneath the ice of the 310 mile-diameter moon.

Measurements of Enceladus’ gravitational field indicate that it has a substantial subsurface ocean estimated to be six miles deep at the south pole beneath a 18-24 mile ice sheet.

Ice particles from the eruption were found to contain large amounts of sodium salt. The presence of the salt indicates that the water has been interacting with rock beneath the surface.

Following a four-year study of data from the Cassini spacecraft, researchers can now add substantial detail to the activities that go on beneath the thick ice sheet. All of their findings are positive for potential life.

The Cosmic Dust Collector on Cassini has revealed tiny grains of dust in orbit around Saturn. The dust was found to be rich in silicon, which separates them from the vast quantities of water-ice particles around Saturn.

The researchers believe that the grains originate on the seafloor of the icy moon.

“On the seafloor, hot water at a temperature of at least 90 degrees Celsius dissolves minerals from the moon’s rocky interior. The origin of this energy is not well understood, but likely includes a combination of tidal heating as Enceladus orbits Saturn, radioactive decay in the core and chemical reactions,” according to a statement from the European Space Agency (ESA).

The hot water naturally rises and quickly comes into contact with cool water. This causes the minerals in the water to condense into nano-grains. These grains, according to scientists, spend a few months to several years rising from the seafloor to the surface before being frozen into ice grains. Some of those grains, along with the ice, is then ejected from the geysers on Enceladus.

Over time the ice grains erode, and release the tiny silicon grains discovered by Cassini.

“It’s very exciting that we can use these tiny grains of rock, spewed into space by geysers, to tell us about conditions on – and beneath – the ocean floor of an icy moon,” says Sean Hsu.

Hsu is a postdoctoral researcher at the University of Colorado at Boulder and the lead author on the paper published in the journal Nature.

On Earth, where silica is found in quartz and sand, it is usually formed by hydrothermal activity.

“We methodically searched for alternative explanations for the nanosilica grains, but every new result pointed to a single, most likely origin,” says Frank Postberg, a Cassini Cosmic Dust Analyser scientist at the University of Heidelberg in Germany, and a co-author on the paper.

Cassini’s gravitational measurements also indicated that the core of the moon is porous enough to allow water from the ocean interact with the interior.

“In fact, it’s possible much of this interesting hot-water chemistry occurs deep inside the moon’s core, not just at the seafloor,” says Hsu.

A paper posted in Geophysical Research Letters in February also indicates the presence of methane on Enceladus.

“This moon has all the ingredients – water, heat, and minerals – to support habitability in the outer Solar System, confirming the astrobiological potential of Enceladus. Enceladus may even represent a very common habitat in the Galaxy: icy moons around giant gas planets, located well beyond the ‘habitable zone’ of a star, but still able to maintain liquid water below their icy surface,” said Nicolas Altobelli, ESA’s Cassini project scientist.

Those looking for possible life on icy moons like Enceladus and Jupiter’s moon Europa were given a confidence boost in January when an entire aquatic ecosystem was found between 2500 feet of ice in Antarctica.