Cassini reveals oxygen atmosphere of Saturn's moon Rhea

From e! Science News Excerpts:

A tenuous atmosphere infused with oxygen and carbon-dioxide has been discovered at Saturn's moon Rhea by the Cassini-Huygens mission, the first time a spacecraft has captured direct evidence of an oxygen atmosphere at a world other than Earth. The NASA-led international mission made the discovery using combined data from Cassini's instruments, which includes a sensor designed and built at UCL's (University College London) Mullard Space Science Laboratory.

Published today in Science Express, results from the mission reveal that the atmosphere of Rhea, Saturn's second largest moon at 1500 km wide, is extremely thin and is sustained by high energy particles bombarding its icy surface and kicking up atoms, molecules and ions into the atmosphere.

The density of oxygen is probably about 5 trillion times less dense than in Earth's atmosphere. However, the formation of oxygen and carbon dioxide could possibly drive complex chemistry on the surfaces of many icy bodies in the universe.

"The new results suggest that active, complex chemistry involving oxygen may be quite common throughout the solar system and even our universe," said Dr Ben Teolis, a Cassini team scientist based at Southwest Research Institute in San Antonio and lead author. "Such chemistry could be a pre-requisite for life. All evidence from Cassini indicates Rhea is too cold and devoid of the liquid water necessary for life as we know it."

All evidence.. For now..