Saturn Moon Rhea's Surprise: Oxygen-Rich Atmosphere

RHEA ON OF THE MOONS OF SATURN

Saturn's second-largest moon Rhea has a wispy atmosphere with lots of oxygen and carbon dioxide, a new study has found. NASA's Cassini spacecraft detected Rhea's atmosphere during a close flyby of the frozen moon in March. The discovery marks the first time an oxygen-rich atmosphere has been found on a Saturn satellite.


Oxygen atmospheres are known to exist on other natural satellites in our solar system. For example, Europa and Ganymede — two frigid moons of Jupiter — are also rich in oxygen.  But the discovery on Rhea suggests that many other large, ice-covered bodies throughout the solar system and beyond may harbor thin shells of oxygen-rich air — and, perhaps, complex chemistry, researchers said.


NASA's Hubble Space Telescope detected thin oxygen atmospheres around Europa and Ganymede in the 1990s. On both Jovian moons, the oxygen comes from surface water ice, which splits into hydrogen and oxygen under heavy bombardment by charged particles from Jupiter. The research team thought something similar might be happening in the Saturn system, which is packed with big, frozen moons. SPACE.COM