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Saturn's Titan --Did an Extraterrestrial Impact Create a Gigantic Outburst of Methane Eons Ago?

 

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By tracking a part of the surface of Saturn's moon Titan over several years, NASA's Cassini mission found a remarkable longevity to the hydrocarbon lakes on the moon's surface. A team led by Christophe Sotin of NASA's Jet Propulsion Laboratory in Pasadena, Calif., fed these results into a model this past spring that suggests the supply of the hydrocarbon methane at Titan could be coming to an end soon (on geological timescales). The Cassini team suggests that the current load of methane at Titan may have come from some kind of gigantic outburst from the interior eons ago possibly after a huge impact. They think Titan's methane could run out in tens of millions of years.

The study of the lakes also led scientists to spot a few new ones in images from Cassini's visual and infrared mapping spectrometer data in June 2010. Titan is the only other place in the solar system besides Earth that has stable liquid on its surface. Scientists think methane is at the heart of a cycle at Titan that is somewhat similar to the role of water in Earth's hydrological cycle - causing rain, carving channels and evaporating from lakes.

However, the fact that the lakes seem remarkably consistent in size and shape over several years of data from Cassini's visual and infrared mapping spectrometer suggests that the lakes evaporate very slowly. Methane tends to evaporate quickly, so scientists think the lakes must be dominated by methane's sister hydrocarbon ethane, which evaporates more slowly.

The lakes are also not getting filled quickly, and scientists haven't seen more than the occasional outburst of hydrocarbon rain at the moon over the mission's eight-plus years in the Saturn system. This indicates that on Titan, the methane that is constantly being lost by breaking down to form ethane and other heavier molecules is not being replaced by fresh methane from the interior.

The true-color image at the top of the page captured by NASA'S Cassini spacecraft before a distant flyby of Saturn's moon Titan on June 27, 2012, shows a south polar vortex, or a mass of swirling gas around the pole in the atmosphere of the moon. The south pole of Titan (3,200 miles, or 5,150 kilometers, across) is near the center of the view.

Since Cassini arrived in the Saturn system in 2004, Titan has had a visible "hood" high above the north pole (see PIA08137). It was northern winter at Cassini's arrival, and much of the high northern latitudes were in darkness. But the hood, an area of denser, high altitude haze compared to the rest of the moon's atmosphere, was high enough to be still illuminated by sunlight. The seasons have been changing since Saturn's August 2009 equinox signaled the beginning of spring in the northern hemisphere and fall in the southern hemisphere for the planet and its many moons. Now the high southern latitudes are moving into darkness. The formation of the vortex at Titan's south pole may be related to the coming southern winter and the start of what will be a south polar hood.

The Daily galaxy via NASA

Comments

If our Moon was birthed from Earth in a catastrophe, and the solar system bodies display similar catastrophes, instead of postulating a stupendous shower of meteorites which could only have come from an exploded planet, perhaps a better idea would be to look for a mechanism that heats the solar body cores on a recurring basis, this core heating being produced by Sol, our sun, by an unknown mechanism possibly the magnetic reversal delay which changes the cosmic ray emissions to the equator and alters the shape of the sun's (and hence all solar bodies positions within) heliosheath.

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