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" It was already a busy news week for Saturn&amp;#039;s moons--more evidence revealed liquid water exists on Enceladus--when Rosalyn Lopes of NASA&amp;#039;s Jet Propulsion Laboratory made the case at the American Geophysical Union conference in San Francisco that icy volcanoes exist on Titan. Lopes, an expert on volcanoes throughout the solar system, studied differences between pictures that the Cassini spacecraft took of an area on Titan in 2004 and again two years later. According to Lopes, bright spots in the pictures show a flow moving across Titan&amp;#039;s surface, and she and her team believe it is the result of cryovolcanoes--features that scientists know exist on other moons, such as Neptune&amp;#039;s Triton. Though they couldn&amp;#039;t discern whether any volcanoes remained active, Lopes says, the bright spots probably indicate the presence of ammonia, which her team thinks would have come from below the surface.  But NASA planetary scientist Jeff Moore does not make the same interpretation. He thinks that the spots in the Cassini images are probably due to methane rainfall that scientists previously have seen on Titan moving across its rolling landscape like a mud slide. So far, Moore says, there&amp;#039;s no solid evidence of any pressure building under Titan&amp;#039;s surface that would produce volcanic eruptions. Alien cryovolcanoes, as they are called, are harder to spot than Earth volcanoes because they&amp;#039;re not mountainous--the telltale signs are instead relatively subtle creases in the terrain caused by tectonic movement, which Moore says scientists sometimes compare to elephant skin. If you look at Titan, he says, there is no elephant-skin-like terrain, and the faint light seen in Cassini&amp;#039;s photos looks more like liquid moving over a bumpy surface formed by Titan&amp;#039;s toxic rain and howling winds. The main obstacle to getting at the truth is Cassini itself. When NASA and the European Space Agency launched the craft in 1997, Moore says, they didn&amp;#039;t have a very good idea of what Titan or Saturn&amp;#039;s other moons were really like. The synthetic aperture radar that took the new images of Titan&amp;#039;s surface works decently, Lopes says, but it provides poor resolution. The most detailed image it could take would be 350 meters (about 380 yards) per pixel, and Moore points out bad conditions can make that as poor as 1 kilometer per pixel. Still, Lopes says, she knows a volcano when she sees one. The flow on the image of Titan is 200 meters thick, and she says it would not have remained so if it weren&amp;#039;t as viscous as the flow from a cryovolcano.  To prove its case, Lopes&amp;#039;s team might need a stroke of luck. If Cassini passed a spot on Titan while an eruption was in progress, the resulting image would demonstrate for certain that the volcanoes exist. Even ice volcanoes are warmer than their surroundings, and Lopes says the radiometer aboard Cassini could tell the difference between the minus 189 F eruption and the atmosphere&amp;#039;s normal temperature of minus 288 F. &amp;quot;It&amp;#039;s the kind of evidence that hits you over the head,&amp;quot; she says. However, Cassini orbits the entire Saturn system, taking radar images of whatever bits of Titan&amp;#039;s surface it happens to focus on during a pass. Even if Cassini operates for another five or six years, Moore says, the spacecraft will probably only map about 60 percent of Titan&amp;#039;s surface, all in low resolution. While Moore says he thinks the evidence for icy volcanoes is far-fetched at the moment, future data could prove Lopes&amp;#039;s team right. &amp;quot;It&amp;#039;s always good to have someone say, &amp;#039;Look, you guys need to prove this case better,&amp;#039;&amp;quot; Lopes says. Until there is a better case--most likely supported by more images--Moore&amp;#039;s criticisms hold weight. And until another spacecraft is capable of penetrating Titan&amp;#039;s blanketlike atmosphere to provide high resolution images, scientists will continue to argue over grainy photos and squiggly lines.  RELATED STORIES * PLUS: Astronomers Find Titan&amp;#039;s Surface Eerily Similar to Earth  * CASSINI: The Spacecraft Reveals Stunning Views of Saturn  * EARLIER: Does Saturn&amp;#039;s Moon Enceladus Harbon Life Underground?  * COMPLETE COVERAGE: News &amp;amp;amp; Analysis on the Future of Space   (Photograph by NASA) "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/space/a12214/4296298/>