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Joe Knapp

Since the Martian atmospheric mass is 2.5e16 kg, and methane is 10 ppb, wouldn't the methane mass there be 2.5e8 kg, and a lifetime of 340 years imply a sink rate of 2.5e8/340 or 740 metric tons per year (about triple the rate quoted above)?

If so, I raise you 4,000 cows.

Oliver Morton

Joe, you may be right, but the sink rate I give in this post was derived from the figures in their abstract on the rate of destruction of methane molecules, rather than being calculated from the starting point of the total atmospheric mass. That said, I was pleased it came to about the same as the estimate in the previous post, which was made in much the way you outline. The discrepancy may be because parts per billion is, I think, a volume measurement, and the methane will be lighter than the bulk of the atmosphere (carbon dioxide) by a ratio of 16 to 44. Do you think that would get our figures straight?

Rick L. Sterling

Is Vladimir Krasnopolsky's Mars Methane research funded by NASA?

Joe Knapp

I'm unsure of whether "ppb" is weight or molar percent. If the latter, then a mole of CH4 weighs only 16 grams compared to a mole of CO2, which is 44 grams, so that would explain the discrepancy neatly.

BTW, if you prefer, one source notes "recent research by Zimmerman et al. (1982) found average CH4 production rates of 0.425 ug CH4/termite/day for the lower termite species.." [url]http://www.iitap.iastate.edu/gcp/studentpapers/1996/atmoschem/brockberg.html[/url]

So 240 metric tons CH4 per year (2,000 cows worth) would be produced by 2.4e8/(0.425e-6*365) or 1.5e12 termites (1.5 teratermite).

The surface area of Mars is 1.44e14 m^2, so that's about one termite per hundred square meters. Not exactly a case for the exterminators!

Oliver Morton

Joe -- LOL. But bear in mind those are lower termites. Lord knows what the higher ones can do.
Rick -- I don't know. None of the observers is NASA staff, and the instrument isn't a NASA facility. But some of the work may be supported by NASA.

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