Martian Methane May Mean Microbes
Biology Monday, March 29, 2004 . This is a SciScoop post by Ricky James
At present neither NASA or ESA has officially announced or released data supporting the detection of methane in the Martian atmosphere. Scientists of both organizations are instead continuing to study their measurements and refine their conclusions before making an announcement that may ultimately herald the first detection of life beyond Earth.
Vittorio Formisano, of the Institute of Physics and Interplanetary Science in Rome, is the chief scientist for the methane-detecting Planetary Fourier Spectrometer (PFS) aboard the Mars Express spacecraft orbiting the planet since December 2003. “We can identify the presence of methane in the Martian atmosphere and we’ve been able to evaluate how much of it there would be,” Dr. Formisano has stated. “Globally, if I average all the data I have, I can find something of the order of 10 or 10.5 parts per billion. It’s detectable, but only if I average a lot of data.”
Michael Mumma of the NASA Goddard Space Flight Center in Maryland also claims to have measured Martian methane, used powerful spectroscopic telescopes based on Earth. Dr. Mumma has seen the spectral signature of methane using the Infrared telescope on Hawaii and the Gemini South observatory in Chile. His team is claiming to have detected variations in the concentrations of methane, with the strongest signals coming from the Meridiani Planum area currently being explored by the NASA Opportunity rover. NASA announced only days ago that Meridiani Planum was once home to a Martian ocean.
Asked if Martian methane is a sign of life, Dr. Mumma said, “I think it is, myself personally. It’s difficult to imagine that primordial methane [from volcanoes] would continue outgassing for four billion years [the age of Mars]. This looks very intriguing.”
Dr. Formisano is more cautious in his predictions. “In my opinion it is most likely of volcanic origin, but I need many more observations. For the moment, we can only say there is evidence of methane, and we have the possibility of accumulating more data and eventually finding the source.”
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3 Responses to Martian Methane May Mean Microbes
Anonymous
March 29th, 2004 at 12:16 pm
Life and volcanoes are not the only possible sources of methane. Comets are loaded with methane. It has been pointed out that the lifetime of methane in the Martian atmosphere is only 300 years, but I’m not suggesting the methane is from a recent cometary impact. An impact would inject the atmosphere with a large amount of dust, vaporized water from the comet itself and from the impact zone, and other gases from the comet including methane. These vaporized compounds would raise the pressure of the atmosphere, but the dust would tend to cause a global cooling. The water would rapidly precipitate out, especially at the poles, trapping other atmospheric components in bubbles in the ice (CO2-ice might also do this).
There is even the possibility of the formation of methane hydrates (the methane hydrate stability zone has been estimated to be as much as 8 km thick at the poles). The top of this zone is only 15 m below the permafrost surface. So the methane may be coming from melting ice. Why would permanent ice be melting? Because Mars is experiencing its own global warming. I posted this idea on slashdot, but it was ignored. What do you folks think?
rickyjames
March 29th, 2004 at 1:17 pm
I guess I don’t know that much about methane hydrate except that it’s an ice-like substance that exists in vast quantities on the ocean floor and is a potential major energy source. Cold temps or high pressure is required to keep it stable – Mars potentially has both, so your theory is certainly possible, seems to me. But I still think it would clinch life on Mars, at least in the past – isn’t methane hydrate considered to be biological in origin, just like petroleum?
Anonymous
March 29th, 2004 at 4:56 pm
On Earth the methane hydrate isn’t itself biological in origin, but the methane that forms it is. When originally posting my idea, I was trying to to provide alternatives to the implicit assumption that methane in the atmosphere is either volcanic or coming from currently living organisms. I suggested cometary sources of methane, but it very well could have come from organisms living (b)millions of years ago. Ice bubbles or hydrates are merely a storage mechanism. I’m intrigued by the statement that more methane seems to be coming from Meridiani Planum. If true, it makes my scenario less likely.
I highly recommend reading the pdf that I already linked to. Not only does it discuss the stability of methane hydrates on Mars, but it raises some interesting questions about how they could be utilized during future exploratory missions by humans (they are sources of both water and methane, after all). They may even prove important for terraforming purposes.
If I keeping posting here, I may eventually have to create a sciscoop account……