Giant ice flows bolster case for volcanoes on Titan

by David Shiga for New Scientist

28 March 2009

SLUSHY water from a hidden ocean may be pooling onto the icy surface of Saturn's moon Titan. Titan's exterior, where the temperature is around -180 °C, is thought to be mostly water-ice, but it may be a different story deep down. Variations in the moon's rate of rotation suggest an ocean could lurk below. An area of Titan called Hotei Arcus appears to fluctuate in brightness on timescales of several months, and in 2005 Robert Nelson of NASA's Jet Propulsion Laboratory in Pasadena, California, and colleagues, suggested this might be the result of "cryovolcanic" eruptions of water from below. Others argued that the flickers were caused by the moon's hazy atmosphere.

The cryovolcanism idea was bolstered in 2008, when observations of Hotei Arcus by a radar instrument aboard NASA's Cassini probe revealed structures that resembled lava flows. Some opponents of the idea still argued these might be deposits of sediment, carried by a flow of methane in the past. Now radar images from Cassini have allowed scientists led by Randolph Kirk of the US Geological Survey in Flagstaff, Arizona, to create a 3D view of the area, which he presented at the Lunar and Planetary Science Conference on 24 March. It turns out that the sinuous structures tower 200 metres above their surroundings. They say that this is consistent with the structures having formed when slushy water and ammonia squirted onto the surface and froze - but that they could not have been produced by a flood of liquid methane depositing sediment. The structures may have formed when slushy water and ammonia squirted onto the surface and froze

If slush volcanoes have been erupting recently, Titan would join a select group of solar system objects - Earth and Io - known to be volcanic at present. The idea of any life surviving in the erupted water is "pretty much out of the question", Kirk says, as it would freeze. As for the ocean below: "Who knows?" he says. "It's conceivable life could be going on down there." Jeff Moore of NASA's Ames Research Center in Moffett Field, California, says it's still not obvious that the structures flowed. "We haven't seen any unambiguous evidence [of volcanism] yet."

[Titan appears to be a good candidate for extraterrestrial life. It seems that the more we discover about this odd little moon the more likely it seems that life may have evolved their independently. I would really like it to be that case that Titan and other locations in our Solar System evolved life on their own. It would strongly indicate that the rest of the Galaxy would be teeming with life. I have a feeling that Earth is far from unique and that it is only our ignorance of other worlds and other star systems that makes us see our home world as particularly special. I look forward to confirmation of life on other worlds. Maybe such a finding will give us the much needed motivation to get some boots on alien ground.]