Euro Space Agency probe begins search for guff gas on Mars The European Space Agency's ExoMars Trace Gas Orbiter (TGO) is to conduct its final aerobraking manoeuvre this evening prior to starting its mission of sniffing for Martian methane. TGO should finally settle into its proper orbit tonight, 400km above the red planet. It was launched nearly two years ago aboard a Russian Proton …
Methane is the most obvious - simplest - hydrocarbon you can get.
It would be interesting to know if it can be trapped in rocks as planets build.
I still remember a colleague who was seconded to work on Russian gas pipelines in the 1980s returning with this odd piece of Russian science (taught as fact) that there was a layer of methane trapped under the Earths crust.
In fact since shale gas became "a thing" it's intrigued me more.
There are a few places in science where Russians seem to have their own ideas.
Possible, but not what the Russians were apparently describing.
The colleague was a PhD 2-MSc type who really knew his stuff which was fluid mechanics and how to design and build very big high-pressure gas pipelines, so it's a bit more than "block said".
The UK was (and is) a world leader ... hence the secondment as part of a UK-USSR deal to buy gas in the 80s ....
Reading up on it just now, as I understand it, the thing can resolve the differences in frequency that having different isotopes (of C, O & H atoms) in the methane would produce, so there's the possibility they could at least partially discriminate between signals suggestive of biological rather than geological origin (granted assuming basic biology similar to that on earth) – so if they see something interesting with the isotopic composition then, even if not definitive proof of life, it would certainly be quite a big deal.
If any oxygen atoms are present in a compound, regardless of their isotopes, we can be 100% certain it's not methane. Methane is a carbon surrounded by and bonded to 4 hydrogens. That's it. There would also, of course, be scientific interest in other organic compounds that do contain oxygen, but those aren't methane.
There was a strong 'biogenic hydrocarbons' movement in the Soviet Union which hypothesised that olivine in the Mantle, combining with water under high pressures and temperatures was the original source of all hydrocarbon deposits.
According to this hypothesis, the methane would migrate up through fractures in the Mantle and Crust and become trapped in sedimentary structures. The actual evidence for this was always rather lacking and the few case studies of hydrocarbons being found in granitic and metamorphic rocks are rather better explained by migration from sediments through faults; or - much to the embarrassment of the Swedes who sunk an expensive borehole in the Siljan Ring - came from the diesel used to lubricate the bit.
The theory never got much traction in the West where there was abundant research into trace chemicals formed by the decomposition products of porphyrins and the like which are found in oil, and which demonstrated that petroleum is, as always suspected, a fossil fuel.
The only prominent advocate in the West was Thomas Gold, previously famous for the 'Steady State Model' of the Universe which rather overshadowed his contributions to the understanding the interaction of the Sun and the Earth.
The Martian methane is probably coming from the serpentinisation process which involves the hydrolysis of ferromagnesian minerals by high temperature water to produce serpentine group minerals - including serpentinite and talc as well as methane. A side reaction involving iron(II) in olivine produces hydrogen.
A definitive answer should come from isotope abundances in the methane. Life, as we know it, preferentially selects for light carbon isotopes so biogenic methane should show a positive C12/C13 ratio compared to methane released by serpentinisation.
On Earth, where we know there is life, the default source of all hydrocarbons is life-related. There are inorganic routes to produce methane, but the volume produced is not likely to be high, and also is unlikely to be trapped in the rock. Even deep hydrocarbons (the ones the original AC is talking about) are probably formed by microbes living in the rock at depth. Shale gas is formed directly from biogenic organic matter in the shale - shale usually has a high organic content, so much so that some shales in the UK are used for brick making because the organic content is high enough to require little additional fuel. Indeed, shales are likely source rocks for hydrocarbon deposits! The organic content in all these cases is biogenic.
The point of Martian methane is that if it isn't associated with volcanic structures, it is a pretty good smoking gun for biological processes here and now, not millions of years ago.
According to the articles I had a quick skim through, on Earth, Methane that forms hydrate can be both biogenic, created by biological activity in sediments, and thermogenic, created by geological processes deeper within the earth. In thermogenic formation, the gas is formed in the same manner as natural gas…through catagenesis of kerogen. I was unable to determine, from what I found, what the relevant percentages were of biogenic to thermogenic Methane.
that when you look at the outer planets like the gas giants - methane is rather the rule than the exception, so why couldn't original hydrocarbon from the solar system be trapped in planets closer to the sun? There may have been oceans of it, far in the past, maybe before life itself?
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