Scientists find likely source of methane on Mars | Hacker News Reader

Scientists find likely source of methane on Mars

phys.org

34 pointsdnetesn15 comments

Methane is in the atmosphere of many planets and moons. I think I recall reading that on Titan it rains liquid methane. Why is methane on Mars any more remarkable than it is elsewhere?

Methane is an extremely simple molecule of carbon and hydrogen. Doesn't seem too surprising to me that it's found all over the place.

That simplicity you speak of means nothing inherently in chemistry, just because it's a simple molecule doesn't mean it will be anywhere. In fact, the sun's radiation degrades methane in the atmosphere, plus the Martian atmosphere is very thin and thinning over time. How then to account for new sources of methane observed by recent observations?

Microbes is one exciting option. Methanogenesis is the process of the production of methane in microbes. It occurs in anaerobic respiration (i.e. the microbes wouldn't need oxygen to make methane - check on Mars). It's the final step in the consumption of old biomass. So, presumably, one could've had microbes feeding on old organic material spewing methane. It would explain why there are spikes in the methane levels, as the sun's radiation would have degraded any old methane over time.

The other option is some sort of volcano or fissure in the planet's surface, which would allow a geochemical source of methane, I don't know much about that process though.

> How then to account for new sources of methane observed by recent observations?

If you read the article, they explain where the methane is coming from.

> The most likely source was a sheet of frozen methane beneath a rock formation

While it is certainly pretty likely, it isn't necessarily known that this rock is part of methane generation.

If it's coming from the ice directly, the ice sheet 'location' doesn't explain whether the methane was from a biotic or abiotic source.

It probably eliminates the already-small likelihood that it is coming from still-extant microorganisms, but it doesn't eliminate their possible involvement in clathrate formation.

The GP's question was rhetorical and his point was that methane can come from both biotic and abiotic processes.

> If you read the article, they explain where the methane is coming from.

This is technically true in a spatial sense, but not at all true in reference to the GP's point. The article specifies only the location of the source, not whether the source is biotic or abiotic.

Sunlight causes methane to decay, and Mars is close enough to the sun for it to decay quickly. IIRC, the estimate is that, without a source to replenish it, any methane in Mars's atmosphere should be gone after only a few centuries.

Because, while common, methane is associated with life. People dream of permafrost leaching methane somewhere on mars, a holdover from its water days.

Article in the Guardian: https://www.theguardian.com/science/2019/apr/01/scientists-u...

"If founded to be extensive, the methane it contains "could support a sustained human presence" on Mars as a possible source of fuel for industrial processes and a propellant for returning manned missions to Earth, he said."

How come? To use Energy you need an oxidant, preferably Oxygen. I googled the atmosphere of Mars:

Carbon dioxide 95.32%

Nitrogen 1.9%

Argon 1.6%

Oxygen 0.13%

Carbon monoxide 0.08%

How are you going to use Methane as a fuel or propellant? 0.13% Oxygen looks suspiciously low.

Water ice + electrolysis = Hydrogen (H2) and Oxygen (O2)

O2 and CH4 (methane) = rocket fuel

H2 + CO2(from atmosphere) + pressure + heat = CH4(more methane) + H2O https://en.wikipedia.org/wiki/Sabatier_reaction

Basically some (SpaceX) have already been planning to use electrolysis of water ice and atmospheric CO2 to create Methane and Oxygen to get rocket fuel via the Sabatier reaction.

Finding existing Methane doesn't change a ton since the building blocks were there anyway, but it may be less energy consuming and complex to mine/melt methane directly and just deal with splitting water by electrolysis, which you were going to have to do anyway to feed the Sabatier Reaction.

Ok, then you assume that you have accessible water too. Still need the Energy for electrolysis. But with solar or nuclear it may be possible.

Most serious Mars return missions plan on simply bringing 1 ton of hydrogen per every 10 tons of desired methane.

That way you can just rely on the martian atmosphere to produce your return fuel instead of embarking on a entire mining expedition.

While it wouldn't support fuel use akin to fuel burning electrical sources on Earth, there are endothermic methods to pull molecular oxygen out of C02. In addition to the water electrolysis already mentioned, C02 can be partially reduced to carbon monoxide with artificial photocatalytic systems, or solid oxide electrolysis (with electrical input instead of solar input). Electrolysis would be counterproductive for primary energy, but rocketry only needs stored energy rather than primary. Otherwise, plants doing photosynthesis in a greenhouse could use C02 from outside the greenhouse. Photosynthetic production of oxygen would have side effects of useful agriculture, but that would be difficult to set up early in a Mars settlement effort.

Not my field but there is some good info on the methane Raptor engines that SpaceX is wanting to use for their Mars colonization.

https://en.wikipedia.org/wiki/Raptor_(rocket_engine_family)#...

tldr;

Something is actively producing methane in Mars but it's not necessary microbial life.

> methane gas dissipates relatively quickly—within around 12 years on Earth

> they conducted two parallel experiments to determine the most likely source of methane on Mars to be an ice sheet east of Gale Crater—itself long assumed to be a dried up lake.

> The most likely source was a sheet of frozen methane beneath a rock formation, which the team believes periodically ejects the gas into the atmosphere.

> "Methane is important because it could be an indicator of microbial life," he said. "But life is not required to explain these detections because methane can be produced by abiotic processes."

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