Once in a great while not finding something can have major implications. Case in point: A team of researchers from University College of London have ruled out the presence of methane on Mars as the result of meteorites. That, according to their report, leaves two possibilities – the methane is created by an interaction between water and volcanic rocks, or the methane is produced by life…

Scientists have ruled out the possibility that methane is delivered to Mars by meteorites, raising fresh hopes that the gas might be generated by life on the red planet, in research published tomorrow (Wednesday 9 December 2009) in Earth and Planetary Science Letters.

Methane has a short lifetime of just a few hundred years on Mars because it is constantly being depleted by a chemical reaction in the planet’s atmosphere, caused by sunlight. Scientists analysing data from telescopic observations and unmanned space missions have discovered that methane on Mars is being constantly replenished by an unknown source and they are keen to uncover how the levels of methane are being topped up.

Researchers had thought that meteorites might be responsible for Martian methane levels because when the rocks enter the planet’s atmosphere they are subjected to intense heat, causing a chemical reaction that releases methane and other gases into the atmosphere.

However, the new study, by researchers from Imperial College London, shows that the volumes of methane that could be released by the meteorites entering Mars’s atmosphere are too low to maintain the current atmospheric levels of methane. Previous studies have also ruled out the possibility that the methane is delivered through volcanic activity.

[Source: EurekAlert]

This is one of those ‘blockbuster at the backdoor’ pieces of information. Yes, there’s; methane on Mars. That’s been known for a while; the question has always been, where does it come from? Apparently, we can rule out deposition by meteorites or comets, and also from volcanic activity. If, at some point, scientists can rule out the water/volcanic rock possibility OR detect some other indicator of life…then one of the greatest questions in science (…and religion, and philosophy…) will be answered: Yes, there is life elsewhere in the universe. It’s fairly clear that the existence of life on Mars is not dramatically obvious, so what are the odds that its existence will kind of sneak up on us, and one day we’ll simply conclude from indirect evidence – there’s life on Mars?