from : http://spectregroup.wordpress.com/2010/06/10/methane-based/
the Simplest Answer is Often Correct
What is Consuming Hydrogen and Acetylene on Titan?
“Two new papers based on data from NASA’s Cassini spacecraft scrutinize the complex chemical activity on the surface of Saturn’s moon Titan. While non-biological chemistry offers one possible explanation, some scientists believe these chemical signatures bolster the argument for a primitive, exotic form of life or precursor to life on Titan’s surface. According to one theory put forth by astrobiologists, the signatures fulfill two important conditions necessary for a hypothesized “methane-based life.” One key finding comes from a paper that shows hydrogen molecules flowing down through Titan’s atmosphere and disappearing at the surface. Another paper maps hydrocarbons on the Titan surface and finds a lack of acetylene. This lack of acetylene is important because that chemical would likely be the best energy source for a methane-based life on Titan. One interpretation of the acetylene data is that the hydrocarbon is being consumed as food. On Titan, where temperatures are around minus 290 degrees Fahrenheit, a methane-based organism would have to use a substance that is liquid as its medium for living processes, but not water itself. Water is frozen solid on Titan’s surface and much too cold to support life as we know it. The list of liquid candidates is very short: liquid methane and related molecules like ethane. While liquid water is widely regarded as necessary for life, there has been extensive speculation published in the scientific literature that this is not a strict requirement. In addition Cassini’s spectrometer detected an absence of water ice on the Titan surface, but loads of benzene and another material, which appears to be an organic compound that scientists have not yet been able to identify. “Titan’s atmospheric chemistry is cranking out organic compounds that rain down on the surface so fast that even as streams of liquid methane and ethane at the surface wash the organics off, the ice gets quickly covered again,” Clark said. “All that implies Titan is a dynamic place where organic chemistry is happening now.””
“Saturn’s giant moon Titan has water frozen as hard as granite and Great Lakes-sized bodies of fed by a complete liquid cycle, much like the hydrological cycle on Earth, but made up of methane and ethane rather than on water. Methane-natural gas-assumes an Earth-like role of water on Titan. It exists in enough abundance to condense into rain and form puddles on the surface within the range of temperatures that occur on Titan. “The ironic thing on Titan is that although it’s much colder than Earth, it actually acts like a super-hot Earth rather than a snowball Earth, because at Titan temperatures, methane is more volatile than water vapor is at Earth temperatures,” even going so far as to call Titan’s climate ‘tropical’, even though it sounds odd for a moon that orbits Saturn more than nine times farther from the sun than Earth. But on Titan, which rotates only once every 16 days, “the tropical weather system extends to the entire planet.””
The team found two types of bacteria living in Lost Hammer that feed off the methane and likely breathe sulfate.
Bacteria Suited for Life on Mars Discovered
“Researchers have discovered that methane-eating bacteria survive in a unique spring located on Axel Heiberg Island in Northern Canada. The Canadian spring’s sub-zero water is so salty it doesn’t freeze and it has no consumable oxygen in it. There are, however, big bubbles of methane that come to the surface, which had provoked the researchers’ curiosity as to whether the gas was being produced geologically or biologically and whether anything could survive in such an extreme hypersaline sub-zero environment. “We were surprised that we did not find methanogenic bacteria that produce methane at Lost Hammer,” Whyte said. “But we did find other very unique anaerobic organisms — organisms that survive by essentially eating methane and probably breathing sulfate instead of oxygen.””
Flammable Methane Rivers, Flammable Methane Rain
“Hills made of ice and rivers carved by liquid methane mark the surface of Saturn’s giant moon. Scientists speculated long ago that some kind of hydrocarbon liquids might flow on Titan. They now know that the fluid that carved the moon’s rivers and channels is methane. “Titan is a flammable world.” But all the oxygen is trapped in ice. “That’s a good thing, or Titan would have exploded a long time ago.”
imagery from Galileo showing emission of gases