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Discovery on Saturn's moon fuels speculation of alien life

Chemical data from Titan returned by NASA's Cassini spacecraft has led scientists to speculate that there are organic processes happening on the Saturnian moon's surface. But, if the data are correct, there are a lot of non-biological explanations that need to be ruled out first.

By Charles Q. ChoiSPACE.com Contributor / June 7, 2010

Some scientists are excited over the prospects of life on Saturn moon Titan. The attached illustration is probably not what Titan looks like.

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New findings have roused a great deal of hoopla over the possibility of life on Saturn's moon Titan, which some news reports have further hyped up as hints of extraterrestrials.

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However, scientists also caution that aliens might have nothing to do with these findings.

All this excitement is rooted in analyses of chemical data returned by NASA's Cassini spacecraft. One study suggested that hydrogen was flowing down through Titan's atmosphere and disappearing at the surface. Astrobiologist Chris McKay at NASA Ames Research Center speculated this could be a tantalizing hint that hydrogen is getting consumed by life.

"It's the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth," McKay said.

Another study investigating hydrocarbons on Titan's surface found a lack of acetylene, a compound that could be consumed as food by life that relies on liquid methane instead of liquid water to live.

"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," McKay said.

However, NASA scientists caution that aliens might not be involved at all.

"Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed," said Mark Allen, principal investigator with the NASA Astrobiology Institute Titan team. "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."

"Both results are still preliminary," McKay told SPACE.com.

To date, methane-based life forms are only speculative, with McKay proposing a set of conditions necessary for these kinds of organisms on Titan in 2005. Scientists have not yet detected this form of life anywhere, although there are liquid-water-based microbes on Earth that thrive on methane or produce it as a waste product.

On Titan, where temperatures are around minus 290 degrees Fahrenheit (minus 179 degrees Celsius), any organisms would have to use a substance that is liquid as its medium for living processes. Water itself cannot do, because it is frozen solid on Titan's surface. The list of liquid candidates is very short -- liquid methane and related molecules such as ethane. Previous studies have found Titan to have lakes of liquid methane.

Missing hydrogen?

The dearth of hydrogen Cassini detected is consistent with conditions that could produce methane-based life, but do not conclusively prove its existence, cautioned researcher Darrell Strobel, a Cassini interdisciplinary scientist based at Johns Hopkins University in Baltimore, Md., who authored the paper on hydrogen appearing online in the journal Icarus.