Stability of an Oxygen Atmosphere on Ganymede
نویسنده
چکیده
Photolysis of water and subsequent escape of hydrogen can give rise to an oxygen atmosphere on Ganymede. Growth of the atmosphere may be limited by escape of fast oxygen atoms formed by photodissociation of 02. Escape of oxygen and hydrogen in an equilibrium configuration should balance net evaporation of water from the satellite's surface and the partial pressure of atmospheric O2 could be as high as 10 -3 mbar. Ganymede should have lost an appreciable quantity of water over geologic time, enough to have coated the surface of the satellite with ice to a depth of about 2 m. An oxygen atmosphere with similar properties might be expected to occur also on Callisto.
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