London, Feb 9 : The Cassini probe has detected negatively charged water molecules in the atmosphere of Saturn's moon Enceladus, which gives credibility to the theory that the natural satellite hides a large body of liquid water beneath its icy skin.

According to a report by BBC News, Cassini found negatively charged water molecules in the atmosphere of Enceladus when making a periodic sweeping past the little moon.

On Earth, such ions are often seen where liquid water is in motion, such as waterfalls or crashing ocean waves.

There are no "rollers" on the moon, but it does have a very active region near its south pole where water vapour and ice particles shoot through cracks in the surface and rise high into the Enceladian sky.

"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.

Where there's water, carbon and energy, some of the major ingredients for life are present.

Cassini has already detected sodium in the plumes - a signature of the dissolved salts you would expect to find in any mass of liquid water that had been in contact with rock deep within the world for a long period.

The latest observations were made using the Cassini plasma spectrometer (Caps).

The instrument was originally flown to acquire data on Saturn's magnetic environment, by measuring the density, flow velocity and temperature of ions and electrons that enter the instrument.

It was never envisaged that Caps would also end up sampling jets at Enceladus and adding to what has become a very compelling story.

"While it's no surprise that there is water there, these short-lived ions are extra evidence for sub-surface water and where there's water, carbon and energy, some of the major ingredients for life are present," said Dr Coates.

"The surprise for us was to look at the mass of these ions. There were several peaks in the spectrum, and when we analysed them we saw the effect of water molecules clustering together one after the other," he said.