Two possible ways methane might be added and removed from to Mars’ atmosphere. NASA’s Curiosity Mars rover has detected fluctuations in methane concentration in the atmosphere, implying both types of activity occur on modern Mars. A longer caption discusses which are sources and which are sinks. (Image Credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan)
Curiosity phones home with some interesting news on Mars that has some scientists scratching their heads: it detected methane. The substance is common in the outer solar system, but the methane detected on Mars came in “whiffs,” apparently from the ground. And while that’s not a smoking gun for life, it is consistent with the kind of microbes that might theoretically eek out a living under the cold, dry surface of the red planet in spots thought to be warmer and wetter:
The NASA scientists at AGU led by MSL project scientist Dr. John Grotzinger emphasized that they do not yet know how the methane is being generated. The process could be biological or not. There are abiotic chemical processes that could produce methane. However, the MSL SAM detections were daily spikes and represent an active real ongoing process on the red planet. This alone is a very exciting aspect of the detection.
The team presented slides to describe how methane could be generated. With the known low background levels of methane at ~ 1 part per billion, an external cosmic source, for example micro-meteoroids entering the atmosphere and releasing organics which is then reduced by sunlight to methane, could be ruled out. The methane source must be of local origin.
Back during the heady days of the Martian meteorite announcement, almost 20 years ago now, I had to endure Pat Buchanan opining on national TV that it’s unlikely Mars would have life and that there’s no possibility of intelligent life elsewhere in the Universe. His contorted reasoning was some convoluted theological malarkey that the Bible rules it out. How the hell that made it on to a news segment about planetary science, I have no idea. But there he was spouting away on Nightline, if memory serves, using up precious network time pitching utter nonsense … and that early example of the willful stupidity yet to come from his wingnut ilk always stuck with me.
Well, Pat might be right about Mars, even if his reasoning was suspect to say the least. But in better informed and less superstitious circles, speculation goes that a dozen or more meters below the surface, the overburden creates enough pressure for water to exist as a liquid. Because of the planet’s eccentric orbit and/or residual heat, it’s possible warmth flows through deep cracks in the crust created when the surface cooled dramatically billions of years ago or subsequently formed by large impacts. The latter is a near statistical certainty. Mars sits adjacent to the main asteroid belt, it’s a veritable cosmic shooting range out there.
That warm water could provide a reservoir giving rise to either abiotic or biological processes that produce methane. Bottom line: it’s not outside the realm of possibility that Mars is harboring a unique science-y gift, carefully wrapped in ancient layers of red soil and oxidized rock, just waiting for the next generation of wonder junkies to discover.
It is not so much the re-emergence of the CH^4, which had been detected by many observations both terrestrial and orbital that recorded the Methane signature over nearly a decade but which was singularly absent in the first few atmospheric analyses by Curiosity, it is the mechanism by which it is suddenly released in the plumes that bamboozle a tad.
There was a correlation of some vagueness that it was observed primarily in the Martian summer, hinting at a possible thaw of sub-surface ice which then released deeper CH^4 deposits that possibly had ancient critter connections, but that is not confirmed of course.
Clathrates, the suspected melt mechanism, were ruled out by the short time-scale of the spikes and the area where they are suspected to be concentrated in the required hydrate forms is at the at the poles..
The release has been characterized as ‘local ‘ to Gale crater…to the North of where the rover is apparently.
Serpentinization has been mooted as a candidate, plenty of Olivine, carbon dioxide and sub-surface water is suspected, but the volume and frequency of spikes seem to rule that out.
Seismic activity is not suspected due to the structure of the planet, and surface degradation by UV is also ruled out due to the physics of the release.
It all rather suggests, quite strongly, that methanogenesis is occurring.
Although that still leaves the mechanism of planetary release still in doubt.
It has to be connected to the environment, either temp or pressure changes sub-surface, and a cap that seems to melt to release then freeze again in sporadic but frequent cycles.
NASA are not being overly drawn or indeed particularly vocal on the phenomena, mainly cos they ain’t got a clue either, but the one test they have that would narrow it down they claim, or infer, that they have not managed yet, in the isotope differentiation possibilities in SAM.
C12 / C13 species analysis would kindda give the game away without actually getting a martian bug under a microscope.
To be frank I think they have already done that, and got a result that they want to retest given the future availability of a plume.
Although they had four spikes in a couple of weeks it beggars belief that they have not already grabbed a handful of gas and enriched it to test the hypothesis, that has been a priority experiment since before the thing launched.
They had several data packets notice of the spikes…they would react stat to grab that sample and let SAM do its thing.
Could be that the news is such a game changer in Cosmology, not to mention cultural challenges in a social context that they want to really nail it without error.
It is a seminal and historical moment in civilization, a discovery so profound and deep that there would be no excuses for a fuck up by NASA…a point they would be well aware of for damn sure.
TBH…methinks they got a critter by the tail, and are just checking!
Of course I could indeed be wrong! ;-(
Cow farts?
@ ^ Trebuchet : I believe the guilty gas mostly comes out the other end ie belches not flatulence but that’s the substance!
Great article here thanks DarkSyde.
Although I’ll just quietly note some folks still think the Viking craft’s results were suggestive if inclonclusive and others reckon they may have accidentally killed some of the life they were looking for bychemical miscalculation :
http://www.daviddarling.info/encyclopedia/V/Vikings_search_for_life_on_Mars.html
Who know? Fascinating though and hopefully we’ll find out in our lifetimes ..