Hacker News Reader

Comment by ams6110 | Hacker News Reader

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.

View on HN

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.

Reply on news.ycombinator.com