Boffins mull life on Titan

Organic snacks for Titanic microbes

By Lucy Sherriff, 25th July 2005

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A group of researchers has proposed a mechanism that could explain the presence of so much methane on Titan - life. The moon's atmosphere is around five per cent methane, and NASA researcher Chris McKay speculates that some of it could be being generated by hydrogen-breathing microbes.

If life does exist on the Saturnian moon, the evidence might have been recorded by the Huygens probe when it landed on Titan on 14 January. The key lies in the likely diet and respiratory habits of the hypothetical microbes, according to New Scientist.

McKay, along with Heather Smith from the International Space University in Strasbourg, thinks that the microbes would breath hydrogen, rather than oxygen, and this could reveal them. If they actually exist.

McKay and Smith estimate that just by breathing the microbes would dramatically deplete the amount of hydrogen available in their immediate environment, reducing it to just one-thousandth of that in the rest of the atmosphere. If the Huygens probe recorded a drop like this, it would be good evidence for some kind of biological process, McKay and Smith argue.

Alternatively, a drop in the amount of acetylene might be enough to give them away. Smith and McKay proposes that the Titanic bugs would eat organic molecules drifting down from the upper atmosphere, either acetylene, ethane or a group of more complex molecules, called tholins. Acetylene is the most calorific of the three, and so is the most likely candidate.

The data they need to test their idea was captured by Huygens' Gas Chromatograph and Mass Spectrometer (GCMS). This is a gas chemical analyser designed to identify and quantify the components of Titan's atmosphere. Hasso Niemann principal investigator of the GCMS says that they hope to at least have numbers for the upper limits of hydrogen.

The paper is to be published in the journal Icarus. ®