Washington: Planetary scientists claim to have for the first time detected presence of oxygen in the atmosphere of Saturn`s moon Dione.
An international team, led by Los Alamos National Laboratory, says it has discovered molecular oxygen ions in the upper-most atmosphere of Dione, one of the 62 known moons orbiting Saturn, thanks to NASA`s Cassini spacecraft, the `Geophysical Research Letters` journal reported.
Dione -- discovered in 1684 by astronomer Giovanni Cassini (after whom the spacecraft was named) -- orbits Saturn at roughly the same distance as our own moon orbits Earth.
The tiny moon is a mere 700 miles wide and appears to be a thick, pockmarked layer of water ice surrounding a smaller rock core.
As it orbits Saturn every 2.7 days, Dione is bombarded by charged particles (ions) emanating from Saturn`s very strong magnetosphere. These ions slam into the surface of Dione, displacing molecular oxygen ions into Dione`s thin atmosphere through a process called sputtering.
Molecular oxygen ions are then stripped from Dione`s exosphere by Saturn`s strong magnetosphere, says the team.
A sensor aboard the Cassini spacecraft called the Cassini Plasma Spectrometer detected the oxygen ions in Dione`s wake during a flyby of the moon in 2010. Now, the team confirmed the presence of oxygen in the ringed planet`s moon.
Team leader Robert Tokar said: "The concentration of oxygen in Dione`s atmosphere is roughly similar to what you would find in Earth`s atmosphere at an altitude of 300 miles.
"It`s not enough to sustain life, but -- 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."