Titan May Have Methane Rainstorms |
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Written by spacetravel.org
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Monday, 12 September 2005 22:48 |
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New calculations based on observations made by the Cassini spacecraft suggest that powerful but brief methane storms may rain down on parts of Saturns moon Titan.
Methane, which makes up about 5% of Titans atmosphere, is thought to ran down on its surface and then evaporate back into clouds, in a cycle similar to the Earths hydrological cycle. The Cassini team believe they have seen thunderstorms on Titan. They have used Cassinis visual infrared mapping spectrometer (VIMS), to study the evolution in height and thickness of long clouds that tend to cluster around the moon's mid-southern latitudes. They observed "vigorous centres" in the clouds as they rose from a height of 23 kilometres to 44 km at speeds of several tens of metres per second. Then, the cloud tops dissipated or fell 10 kilometres over the next 30 minutes. This suggests the clouds "evolve convectively and dissipate through rain," as Caitlin Griffith of the University of Arizona claims.
The Cassini spacecraft, in orbit around Saturn, and the Huygens probe, which was sent down to Titan in January 2005 both show dark, river-like channels carved into higher, lighter terrain, as well as a round feature that resembles a lake, near the south pole. Radar data from Cassini show canyon-like features ending in triangular slopes that seem to be littered with cobbles a few centimetres wide, which may indicate flash flooding, and sinuous shapes resembling rivers that only branch off in a few places. The size, curviness and number of branches are similar to channels in the Earths desert that are carved in heavy bursts of rainfall which seep into the porous soil quickly.
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