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Methane plays principal role on Titan

 Data sent by Huygens probe indicate that the physical processes shaping Titan are much the same as those shaping Earth. There were precipitation, erosion, mechanical abrasion and other fluvial activity on Titan.Images have shown a complex network of narrow drainage channels running from brighter highlands to lower, flatter, dark regions. These channels merge into river systems running into lakebeds featuring offshore ‘islands’ and ‘shoals’ remarkably similar to those on Earth.

While many of Earth’s familiar geophysical processes occur on Titan, the chemistry involved is quite different. Instead of liquid water, Titan has liquid methane, a simple organic compound that can exist as a liquid or gas at Titan’s sub-170°C temperatures, rather than water as on Earth. Instead of silicate rocks, Titan has frozen water ice. Instead of dirt, Titan has hydrocarbon particles settling out of the atmosphere, and instead of lava, Titanian volcanoes spew very cold ice.

Titan’s rivers and lakes appear dry at the moment because when it rains the liquid rapidly sinks into the soil leaving behind dry river and lakebeds. But methane rain may have occurred not long ago. Images show small rounded pebbles in a dry riverbed. Spectra measurements (colour) are consistent with a composition of dirty water ice rather than silicate rocks.

Titan’s soil appears to consist at least in part of precipitated deposits of the organic haze that shrouds the planet. This dark material settles out of the atmosphere. When washed off high elevations by methane rain, it concentrates at the bottom of the drainage channels and riverbeds contributing to the dark areas seen in Huygens images.

The material beneath the surface’s crust has the consistency of loose sand, possibly the result of methane rain falling on the surface over eons, or the wicking of liquids from below towards the surface.

Heat generated by Huygens warmed the soil beneath the probe and bursts of methane gas boiled out of surface material, reinforcing methane’s principal role in Titan’s geology and atmospheric meteorology — forming clouds and precipitation that erodes and abrades the surface.

posted by: kyawoo at 20:46 | link | comments |
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