Cassini Spacecraft finds Oxygen on Saturn’s Moon Dione

According to a press release from the Los Alamos National Laboratory, there appears to be oxygen present in the atmosphere of one of the moons which orbit Saturn. The scientists which are made up of an international research team said that they have detected molecular oxygen ions (O2+) in the upper-most atmosphere of Dione.

The discovery was made using instruments onboard NASA’s Cassini spacecraft which launched from Earth back in 1997 on a mission to explore the ringed planet and its system of moons. The full report from the research team was published recently in Geophysical Research Letters.

Dione is just one of the 69 moons which orbit Saturn and was discovered in 1684 by astronomer Giovanni Cassini for whom the Cassini spacecraft was named. Dione sits in an orbit roughly the same distance as out moon is from the Earth, but that is where the similarity ends.

Dione is small, only about 700 miles across. The surface looks to be a thick layer of water ice, scarred with impact marks. The core is believed to be solid and comprised of rock. Although Saturn is, in comparison, extremely large, Dione races around the planet completing an orbit in just under 3 days.

The Cassini Plasma Spectrometer (CAPS), onboard the spacecraft, detected oxygen ions during a flyby of the moon in 2010. According to the release, Los Alamos researchers Robert Tokar and Michelle Thomsen noted the presence of the oxygen ions.

“The concentration of oxygen in Dione’s atmosphere is roughly similar to what you would find in Earth’s atmosphere at an altitude of about 300 miles,” Tokar said. “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.”


Perhaps even more exciting is the 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. Future missions to Europa could help unravel questions about that moon’s habitability.

The full report from the research is available for viewing at: http://www.agu.org/journals/gl/gl1203/2011GL050452/