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News  Titan’s surface organics surpass oil reserves on Earth
Saturn’s orange moon Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth, according to new Cassini data. The hydrocarbons rain from the sky, collecting in vast deposits that form lakes and dunes. The new findings from the study led by Ralph Lorenz, Cassini radar team member from the Johns Hopkins University Applied Physics Laboratory, USA, are reported in the 29 January 2008 issue of the Geophysical Research Letters. "Titan is just covered in carbon-bearing material—it’s a giant factory of organic chemicals," said Lorenz. “This vast carbon inventory is an important window into the geology and climate history of Titan.” At a balmy minus 179º C , Titan is a far cry from Earth. Instead of water, liquid hydrocarbons in the form of methane and ethane are present on the moon's surface, and tholins probably make up its dunes. The term ‘tholins’ was coined by Carl Sagan in 1979 to describe the complex organic molecules at the heart of prebiotic chemistry. Cassini has mapped about 20% of Titan's surface with radar. Several hundred lakes and seas have been observed, with each of several dozen estimated to contain more hydrocarbon liquid than Earth's oil and gas reserves. The dark dunes that run along the equator contain a volume of organics several hundred times larger than Earth's coal reserves.
"This global estimate is based mostly on views of the lakes in the northern polar regions. We have assumed the south might be similar, but we really don’t yet know how much liquid is there," said Lorenz. Cassini's radar has observed the south polar region only once, and only two small lakes were visible. Future observations of that area are planned during Cassini’s proposed extended mission. Scientists estimated Titan's lake depth by making some general assumptions based on lakes on Earth. They took the average area and depth of lakes on Earth, taking into account the nearby surroundings, like mountains. On Earth, the lake depth is often 10 times less than the height of nearby terrain. "We also know that some lakes are more than 10 m or so deep because they appear literally pitch-black to the radar. If they were shallow we'd see the bottom, and we don't," said Lorenz.
“We are carbon-based life, and understanding how far along the chain of complexity towards life that chemistry can go in an environment like Titan will be important in understanding the origins of life throughout the universe,” added Lorenz. Cassini's next radar flyby of Titan is on 22 February 2008, when the radar instrument will observe the landing site of ESA’s Huygens probe. Notes for editors: The Cassini-Huygens mission is a cooperative project of NASA, ESA and the Italian Space Agency (ASI). The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology, manages the Cassini-Huygens mission for NASA's Science Mission Directorate. JPL designed, developed and assembled the Cassini orbiter. ESA developed the Huygens Titan probe, while ASI managed the development of the high-gain antenna and the other instruments of its participation. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.
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