Saturn’s Icy Moon Dione Has Oxygen Atmosphere
A NASA spacecraft circling Saturn has discovered a wispy oxygen atmosphere on the ringed planet’s icy moon Dione, but you wouldn’t want to live there. For one thing, you wouldn’t be able to breathe — Dione’s atmosphere is 5 trillion times less dense than the air at Earth’s surface, scientists say.
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. On Dione, there is one oxygen ion for every 2,550 cubic feet (90,000 cubic meters), but it’s still enough to qualify as an atmosphere, Cassini mission scientists announced Friday (March 2).
“We now know that Dione, in addition to Saturn’s rings and the moon Rhea, is a source of oxygen molecules,” Cassini team member Robert Tokar of the Los Alamos National Laboratory in New Mexico, who led the new study, said in a statement. “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.