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CH4 on Mars? Sources? Sinks?

September 18th, 2007 by Hasenkopf · 2 Comments

Has methane been detected in the Martian atmosphere? Some sources say “Yes, we’ve detected it!” (ground-based Krasnopolsky, 2004 and the Mars Express Planetary Fourier Spectrometer – Formisano, 2004). While others say, “Uh, no you didn’t.” If methane is on Mars, then there’s a lot of explaining to do! Taking into account the only known sink (UV photolysis), a methane molecule in the Martian atmosphere has a lifetime of ~300 years. With no known sources, methane should have been depleted from the atmosphere a very long time ago.

Recently Melissa Trainer (a postdoc for the Toon and Tolbert research groups at LASP, CIRES, and CU) gave a talk at the CU Astrobiology journal club that presented the case for and against Martian methane, its possible spatial and temporal variation, and its possible sources and sinks. She briefly discussed her own research on exotic Martian water-carbon dioxide clathrates that – unlike any clathrate on Earth – could form on its planet’s surface, and more specifically at the Martian poles. These clathrates could act as both a source and a sink by storing and expelling methane molecules from these icy “cages.” Check out the powerpoint show here by right-clicking the link and select “save link as” (or your browser may be configured to view it as is).

Tags: Mars · planetary atmospheres

2 responses so far ↓

  • 1 Sean Davis // Sep 20, 2007 at 8:46 am

    One important point here that you didn’t quite spell out is — given the “short” lifetime of methane in Mars’ atmosphere, the presence of methane could be an indicator of life!

    Of course, if there are things like clathrates continuously generating methane, maybe it’s presence wouldn’t be an indicator of life.

  • 2 Hasenkopf // Sep 20, 2007 at 9:04 am

    You’re absolutely right! It very well *could* be the presence of life! And I suppose that’s the exciting part about no one being able (so far) to find abiotic processes that generate methane.

    As a sidenote (which Fartmeister may particularly appreciate), Krasnopolsky, et al., 2004 estimate Mars methane concentrations of 10+/- 3ppb. This, according to an amusing blog entry linked at the bottom of this comment, corresponds to the yearly production of methane by about 2,000 cows. Google “cows” and “Mars,” and you get a surprising number of hits….

    2000 cows blog entry:
    http://mainlymartian.blogs.com/semijournal/2004/03/two_thousand_co.html

    Learn more about the controversy of covering up the presence of cows on Mars at:
    http://www.mulletman.org/cowsonmars.html

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