Molecular Oxygen Ions Around Icy Moon of Saturn Dione

NASA’s Cassini spacecraft has “sniffed” molecular oxygen ions around the icy moon of Saturn 

Dione for the first time, confirming the presence of a very tenuous atmosphere. The oxygen ions are quite sparse, one for every 0.67 cubic inches of space (one for every 11 cubic centimeters of space) or about 2,550 per cubic foot (90,000 per cubic meter), show that Dione has an extremely thin neutral atmosphere. Dione’s atmosphere was detected by NASA’s Cassini spacecraft, which spotted an ultra-thin layer of oxygen ions so sparse that it is equivalent to conditions 300 miles (480 kilometers) above Earth. According to Cassini team member Robert Tokar of the Los Alamos National Laboratory in New Mexico, who led the new study they know that Dione, in addition to Saturn’s rings and the moon Rhea, is a source of oxygen molecules. This shows that molecular oxygen is actually common in the Saturn system and reinforces that it can come from a process that doesn’t involve life. Dione is one of Saturn’s smaller moons and is about 698 miles (1,123 km) wide. It orbits Saturn once every 2.7 days at a distance of about 234,000 miles (377,400 km), roughly the same as that between Earth and its moon, according to a NASA description. According to researchers the oxygen on Dione may potentially be created by solar photons or high-energy particles that bombard the Saturn moon’s ice-covered surface, kicking up oxygen ions in the process. Another idea suggests that geologic processes on Dione could feed the moon’s atmosphere. Scientists are now digging through Cassini data on Dione to look at this moon in more detail.