Life on Titan?

Recent data obtained by NASA’s Cassini spacecraft has discovered interesting chemical reactions happening on Saturn’s cloud covered moon Titan. Could these reactions be the sign of a primitive form of life on the surface? Or just complex non-biological chemical reactions?

The two main findings are that there is a flow of hydrogen molecules down from the atmosphere to Titan’s surface and that when the molecules reach the surface they disappear. The other finding is that there is a lack of the hydrocarbon acetylene on the moon.

These are very important as the type of life theorized to exist on Titan would have to be a methane based life-form, and according to Chris McKay an astrobiologist at NASA’s Ames Research Center hydrogen and acetylene are the two chemicals that a methane based life-form would consume. One interpretation of the acetylene data is that the hydrocarbon is being consumed as food. But McKay said the flow of hydrogen is even more critical because all of their proposed mechanisms involved the consumption of hydrogen.

“We suggested hydrogen consumption because it’s the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth,” McKay said. “If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth.”

In addition to this the spectrometer on the Cassini probe 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. This has lead scientists to believe that the organic compounds are covering up the water ice in layers from a few millimeters to a few centimeters and even deeper in places.

“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,” Roger Clark, a Cassini team scientist said. “All that implies Titan is a dynamic place where organic chemistry is happening now.”

However methane based life is completely theoretical and scientists have found no solid evidence to prove its existence, although there are water based microbes on earth that thrive on methane or produce it as a waste product. Unfortunately on Titan there is no chance of water based life because at a chilly -180 Celsius (-290 fahrenheit) water on the surface is frozen as hard as steel, and the only liquid found on the surface so far is methane with small amounts of ethane as well.

But dont get all excited just yet, Cassini scientists have said that a biological explantion for the reactions happening on Titan should only be folowed up after all other non-biological explantions have been used up. “We have a lot of work to do to rule out possible non-biological explanations. It is more likely that a chemical process, without biology, can explain these results – for example, reactions involving mineral catalysts.” Said Mark Allen, principal investigator with the NASA Astrobiology Institute Titan team.

“These new results are surprising and exciting,” said Linda Spilker, Cassini project scientist at JPL. “Cassini has many more flybys of Titan that might help us sort out just what is happening at the surface.”