Saturn's frigid moon holds wisps of oxygen, scientists say
There鈥檚 oxygen around Dione, a research team led by scientists at New Mexico鈥檚 announced on Friday. The presence of molecular oxygen around Dione creates an intriguing possibility for organic compounds 鈥� the building blocks of life 鈥� to exist on other outer planet moons.
One of Saturn鈥檚 62 known moons,聽Dione (pronounced DEE-oh-nee) is 698 miles (1,123 km) in diameter. It orbits Saturn at about the same distance that our Moon orbits Earth. Heavily cratered and by long, bright scarps, Dione is made mostly of water ice and 聽rock. It makes a complete orbit of Saturn every 2.7 days.
Data acquired during a flyby of the moon by the Cassini spacecraft in 2010 have been found by the Los Alamos researchers to confirm the presence of molecular oxygen high in Dione鈥檚 extremely thin atmosphere 鈥� so thin, in fact, that scientists prefer the term exosphere.
While you couldn鈥檛 take a deep breath on Dione, the presence of O2 indicates a dynamic process in action.
鈥淭he concentration of oxygen in Dione鈥檚 atmosphere is roughly similar to what you would find in Earth鈥檚 atmosphere at an altitude of about 300 miles,鈥� said Robert Tokar, researcher at Los Alamos National Laboratory and lead author of the published in Geophysical Research Letters. 聽鈥淚t鈥檚 not enough to sustain life, but鈥攖ogether with similar observations of other moons around Saturn and Jupiter鈥攖hese 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.鈥�
On Dione the energy source is Saturn鈥檚 powerful magnetic field. As the moon orbits the giant planet, charged ions in Saturn鈥檚 magnetosphere slam into the surface of Dione, stripping oxygen from the ice on its surface and crust. This molecular oxygen (O2) flows into Dione鈥檚 exosphere, where it is then steadily blown into space by 鈥� once again 鈥� Saturn鈥檚 magnetic field.
Cassini鈥檚 instruments detected the oxygen in Dione鈥檚 wake during an April 2010 flyby.
Molecular oxygen, if present on other moons as well (say, Europa or Enceladus) could potentially bond with carbon in subsurface water to form the building blocks of life. Since there鈥檚 lots of water ice on moons in the outer solar system, as well as some very powerful magnetic fields emanating from planets like Jupiter and Saturn, there鈥檚 no reason to think there isn鈥檛 more oxygen to be found鈥� in our solar system or elsewhere.
