These two images demonstrate how, over time, rain can carve landscapes into formations that look like aspects of volcanoes. The images are computer simulation models of landform evolution by Alan Howard at the University of Virginia.
Credit: A. Howard
PASADENA: Have the surface and belly of Saturn's smog-shrouded moon, Titan, recently simmered like a chilly, bubbling cauldron with ice volcanoes, or has this distant moon gone cold?
A pair of NASA scientists have analysed data collected by the Cassini spacecraft and suggest that Titan may be much less geologically active than some researchers have thought. The team concluded that Titan's interior may be cool and dormant and incapable of causing active ice volcanoes.
"It would be fantastic to find strong evidence that clearly shows Titan has an internal heat source that causes ice volcanoes and lava flows to form," said Jeff Moore, lead author of the paper in Icarus and a planetary scientist at NASA's Ames Research Centre in California.
"But we find that the evidence presented to date is unconvincing, and recent studies of Titan's interior conducted by geophysicists and gravity experts also weaken the possibility of volcanoes there."
Do the ice volcanoes exist?
Scientists agree that Titan shows evidence of having lakes of liquid methane and ethane, and valleys carved by these exotic liquids, as well as impact craters.
However, a debate continues to brew about how to interpret the Cassini data on Titan. Some scientists theorise that ice volcanoes exist and suggest energy from an internal heat source may have caused ice to rise and release methane vapors as it reached Titan's surface.
But in the new paper, the authors conclude that the only features on Titan's surface that have been unambiguously identified were created by external forces - such as objects hitting the surface and creating craters; wind and rain pummeling its surface; and the formation of rivers and lakes.
Recent analysis not convincing
"Titan is a fascinating world," said Robert Pappalardo, a research scientist at NASA's Jet Propulsion Laboratory, in California, and former project scientist for NASA's Cassini mission.
"Its uniqueness comes from its atmosphere and organic lakes, but in this study, we find no strong evidence for icy volcanism on Titan."
In December 2010, a group of Cassini scientists presented new topographic data on an area of Titan called Sotra Facula, which they think makes the best case yet for a possible volcanic mountain that once erupted ice on Titan.
Although Moore and Pappalardo do not explicitly consider this recent topographic analysis in their paper, they do not find the recent analysis of Sotra Facula to be convincing so far. It remains to be seen whether ongoing analyses of Sotra Facula can change minds.
