Atmospheric/Exospheric Characteristics of Icy Satellites

The atmospheres/exospheres of icy satellites greatly vary from one to the next in terms of density, composition, structure or steadiness. Titan is the only icy satellite with a dense atmosphere comparable in many ways to that of the Earth’s atmosphere. Titan’s atmosphere prevents the surface from direct interaction with the plasma environment, but gives rise to Earth-like exchanges of energy, matter and momentum. The atmospheres of other satellites are tenuous. Enceladus’ atmosphere manifests itself in a large water vapor plume emanating from surface cracks near the south pole. Io’s SO2 atmosphere originates from volcanoes. Europa’s tenuous O2 atmosphere is produced by intense radiation bombardment. This chapter reviews the characteristics of the atmospheres of Titan, Enceladus, Io and Europa based on observations.