The discovery, made by NASA’s Cassini spacecraft, suggests that oxygen and other ingredients for life may be abundant on icy celestial bodies, according to a study by Los Alamos National Laboratory scientists and international research team.

“…together with similar observations of other moons around Saturn and Jupiter -- these are definitive examples of a process by which a lot of oxygen can be produced in icy celestial bodies that are bombarded by charged particles or photons from the Sun or whatever light source happens to be nearby,” says Las Alamos researcher Robert Tokar.

Dione orbits Saturn at roughly the same distance as our own moon orbits Earth. As it orbits Saturn every 2.7 days, the 700 mile-wide moon is hit by charged particles (ions) emanating from Saturn's very strong magnetosphere, including oxygen.

Molecular oxygen ions are then displaced into Dione’s atmosphere, after which they are stripped from the moon’s exosphere by Saturn’s magnetosphere.

A sensor aboard the Cassini spacecraft called the Cassini Plasma Spectrometer (CAPS) first detected the oxygen ions in Dione's wake during a flyby of the moon in 2010.

Tokar says the oxygen level in the icy moon is about the same level as one found in Earth’s atmosphere at an altitude of 300 miles, and is not enough to sustain life.

However, the existence of oxygen brings about more exciting possibility that on a moon with subsurface water, such as Jupiter's moon Europa, molecular oxygen could combine with carbon in subsurface lakes to form the building blocks of life.

From News reports