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J. Lunine (LPL Tucson and INAF-IFSI Rome)
Prior to the arrival of Cassini and Huygens at Saturn, visions of the surface of Titan ranged from a world covered in extensive seas of ethane and methane, to a body much like Callisto shrouded by a hazy atmosphere. The actual surface of Titan, revealed by the Huygens probe and a series of continuing flybys by the Orbiter, corresponds to neither of these extremes. Ethane-methane oceans do not cover the surface, but the signature of liquid methane and ethane just below the optical surface is found at the landing site, and circumstantial evidence for exposed liquid bodies is seen in the orbiter RADAR data. Two impact craters are evident on the surface, but overall Titan lacks preserved signatures of its impact history and instead shows a range of features best interpreted as due to volcanism of some kind. When combined with modelling and chemical evidence from Orbiter and Probe, the style of volcanism most likely on Titan involves partial melts of ammonia and water, expressed in a variety of landforms corresponding to varying viscosities (hence melt temperatures) and gas content of the volcanic fluids. The surface of Titan is also worked by low viscosity liquids, presumably ethane and methane (with some dissolved nitrogen), evidenced by networks of channels near the Huygens landing site, and by winds. Overall, the surface of Titan exhibits effects of geologic and atmospheric processes remarkably akin to those on Earth, but operating on very different materials under much colder conditions.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.