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Coastline on Titan
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The deposits form when solar ultraviolet radiation and charged particles react at high altitudes with Titan’s abundant methane to produce carbon- and hydrogen-bearing (hydrocarbon) molecules like ethane and acetylene, and more complex nitrogen-bearing molecules generally called tholins. These products drift down to the surface as aerosols much in the same way smog particles on Earth form and coat surfaces. On Titan however these deposits may accumulate to thicknesses of hundreds of metres deep.
The dunes are composed of sand-sized material that agglomerated, either during its descent or when reworked by geological processes on the surface. The ice and organic landforms are as different from one another as they are spectacular. To the north of Huygens’ landing site are the bright highlands, displaying channels in a very ramified pattern, branching four or five times as they climb into the hills.
Stereoscopic images from the Descent Imager/Spectral Radiometer (DISR) camera on Huygens have now been analysed and show that some of the ridges between the channels rise to 150 - 200 metres in height, with slopes of thirty degrees. “This is extremely rugged terrain,” says Soderblom. The shape suggests that they are drainage channels, cut by liquid methane falling as rain.
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(Dettagli)
