Starship Asterisk*

The Mysterious Methane of Mars

Explanation: What's creating methane on Mars? Recent measurements from the robotic Curiosity rover currently rolling across Mars indicate a surprising 10-fold increase in atmospheric methane between measurements only months apart. Life is a major producer of methane on Earth, and so speculation is rampant that some sort of life -- possibly microbial life -- is creating methane beneath the surface of Mars. Other possibilities do exist, though, with a leading model being the sudden release of methane produced by the mixing of specific soil chemicals with underground water. Proposed origins of Martian methane are depicted in the featured illustration. The origin of Mars' methane is a very active area of research, with missions like Curiosity and India's Mars Orbiter Mission searching for clues by measuring methane abundance changes and possible byproducts of different methane-producing processes.

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That's very interesting. But by my calculations, the highest localised reading from Curiosity (7 parts per billion) suggested a proportion of methane ~100 times smaller than in Earth's pre-industrial atmosphere (or ~250 times smaller than in our current atmosphere). And with the atmospheric pressure on Mars being (in nice round figures) ~100 times lower than on Earth, I think we're talking ~10,000 times fewer molecules of methane, per unit volume. So, it is also interesting that the "sniffing" instrument on Curiosity is so sensitive.

Nitpicker wrote:That's very interesting. But by my calculations, the highest localised reading from Curiosity (7 parts per billion) suggested a proportion of methane ~100 times smaller than in Earth's pre-industrial atmosphere (or ~250 times smaller than in our current atmosphere). And with the atmospheric pressure on Mars being (in nice round figures) ~100 times lower than on Earth, I think we're talking ~10,000 times fewer molecules of methane, per unit volume.

Would you say, Nit, that if we assume that all the methane in the atmosphere of Mars is produced by life forms, that would also mean that the ~10,000 times fewer molecules of methane per unit volume of Martian atmosphere compared with the atmosphere of Earth, would also mean that the methane-producing biomass of Mars would be 10,000 times smaller on Mars than on Earth?

It would of course be fantastically interesting if there really is life on Mars. The way I read you, Nit, there can only be relatively little of it. Can we be talking about relatively small favorable sites on Mars that are not only habitable, but inhabited?

Which brings me back to the Earth. Do we know if the biomass of the Earth has ever - well, in the last three billion years or so - been thousands of times smaller than it is now?

Ann

My thinking is that the source of this relatively small amount of methane is probably going to be very difficult, if not impossible, to determine with much certainty, anytime soon. For now, I'm inclined to favour the "organic" (but lifeless) chemistry hypothesis [and I think that's a tasteful use of scare quotes, geck].

As for Earth, I am certain that at some point in the past, the total biomass was negligible. Likewise for some point in the future.

Guess we will be drilling for water...instead of oil....but we can use the methane in various ways....

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Ann wrote:Which brings me back to the Earth. Do we know if the biomass of the Earth has ever - well, in the last three billion years or so - been thousands of times smaller than it is now?

Since life started from a few biomolecules and cells, the answer is yes.

AFAIK, the composition of Earth's atmosphere was dramatically altered by micro-organisms, which led to the high concentration of oxygen. It would be interesting to study if some known bacteria could produce a similar effect with methane on Mars.

If the conductivity and heat production of Martian rocks is much like their earth counterparts, you probably only have to get a few kilometers deep to get above the melting point of ice, especially since the melting point of Ice I decreases with pressure.

Nitpicker wrote: it is also interesting that the "sniffing" instrument on Curiosity is so sensitive.

Seems very sensitive... What is the margin of error in measurements made by the instrument? Also, wondering if the rover info can try to map/triangulate to at least one source given enough measurements and (mars) weather info. Probably not with only one data source, and a moving source at that. However slow he is moving. Maybe Nasa should consider a 'sniffer' mission that deploys a couple of dozen static weather/sniffer stations in that area where the rover got its whiff of 'martian cows'.

Climate change.

What's creating methane on Mars? Beefheart knew. It's those Big Eyed Beans from Venus.

Methane itself is a "sort of" a cathrate in that it's carbon atom surrounded by hydrogen atoms so, "Would the methane's carbon atom ever give a clue to when it was formed either by geological or cosmological mechanisms or release by the breakdown from larger molecules?" That is - if the underground methane is the "Russian doll" of clathrates are there potentially different isotopes of carbon that could differentiate their mechanism of creation that would substantiate when and where it came from? It seems like when the cathrate's molecule's isotopes were formed would be different from when it's earlier methane's isotopes were incorporated that would be different when the current atmospheric methane is being formed. I probably this sounds like - Who's on first? What's on second? And I don't knows on third! Most likely I'd better stay at home and let actual chemists figure this out before the Earth's engineers get people to Mars so the future Martian explorers can go drilling for cathrates for the Martian chemists to analyze.