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A New Angle on Martian Methane

Posted by CowboyNeal on Fri Oct 06, 2006 06:24 AM
from the gassy-mysteries dept.
dusty writes "A recent hypothesis paper entititled 'Martian CH4: Sources, Flux, and Detection' delves into the production of methane on Mars. This hypothesis compares Mars with South Africa, and draws the conclusion that the radiolysis of martian ice and water while reacting with carbon dioxide can produce enough methane to account for recently observed concentrations. Methane is important because it is hard to explain. It has a short half-life and must be replenished frequently. As recently as 2005 the public line from NASA/JPL was that the methane could be produced by volcanism. Mars' dormant Olympus Mons is the largest volcano in the solar system but auspiciously quiet. A recent study from NOAA throws into question the whole idea stating, 'If Mauna Loa is a valid terrestrial analog, our findings suggest that volcanic activity is not a significant source of methane to the Martian atmosphere.'"
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  • by 3.5 stripes (578410) on Friday October 06 2006, @06:26AM (#16334541)
    as anyone with 3 male roommates can testify to.
    • There's a lot of sci-fi shows that say the aliens breathe methane to live. Well since we fart methane and breathe oxygen, do martians breathe methan and fart oxygen?

      We could use each other as space suits.
      • "Hey Froolak, I have an EVA to do. Mind if I stick my head up your ass?"

        Um...I think I'll wait for body mods so that I don't require constant breathing in space.
        • You wouldn't have to stick your head in there. Just put your face close enough and the aliens would do the same.
          • I was thinking of a way to maintain positive pressure around the various holes humans seem to carry around with their heads. I guess it would be easier to drive a space scooter if you could actually use optical receptors that aren't just registering Froolak's last meal.
  • It has a short half-life and must be replenished frequently.

    Methane has a short half-life? I thought only radioactive elements had "half-lifes". Either I am just dumb about this (entirely possible) or someone chose their words poorly.
    • Re:Radioactive? (Score:4, Informative)

      by MichaelSmith (789609) on Friday October 06 2006, @06:31AM (#16334577) Homepage Journal
      I thought only radioactive elements had "half-lifes".

      The term can be applied to anything which decays with time, though radioactive decay would probably give the most attractive decay curve.

      • Re:Radioactive? (Score:5, Insightful)

        by radtea (464814) on Friday October 06 2006, @09:09AM (#16335925)
        The term can be applied to anything which decays with time, though radioactive decay would probably give the most attractive decay curve.

        You get the same curve from anything that has a probability of decay that is independent of time.

        If the probability of decay, destruction or loss for an individual atom is L per unit time, then for N atoms the rate of change of N is:

        dN/dt = -L*N

        and integrating gives N = No*exp(-L*t) where No is the number of atoms at some arbitrary t=0.

        So for any situation where you have a constant decay probability you will get the same curve. For methane in the Martian atmosphere the rate of decay is pretty much constant due to solar ultra-violet radiation breaking up the molecules. Therefore, if there were no source the amount of methane in the atmosphere would drop exponentially.
      • Hubba, hubba! Check out the decay curves on that isotope! Wowzers!
      • While radioactive elements give a more attractive decay curve, Methane smells more like decay, and is thus less attractive to those with curves.
    • The article means half-life of methane in atmosphere of the Mars.
    • Re: (Score:3, Insightful)

      According to the article (first paragraphs even...), Methane is chemically broken down by sunlight over a few hundred years.

      MadCow.
    • Re:Radioactive? (Score:4, Informative)

      by B5_geek (638928) on Friday October 06 2006, @06:38AM (#16334615)
      It's been awhile since biology class, but I'll do my best.

      UltraViolet radiation/light breaks down the Hydrongen bonds in Methane (CH3) thus 'destabalising' the molecule.
      Mars has no ozone layer too, (which blocks a large % of ground-level UV)
      • Well, if you got that from Biology, no wonder it's a bit off! I'll give the chemist's take on it - you've got the UV bit right, but hydrogen bonds don't exist in methane, which is CH4 (CH3 is a methyl group) What it can do is break the covalent bonds between carbon and hydrogen atoms, splitting the molecule. I don't know for sure, but intuition tells me you'll get a CH3- anion, and a H+ cation. Not sure though, you might get a carbocation...
        • Re: (Score:2, Informative)

          I don't know for sure, but intuition tells me you'll get a CH3- anion, and a H+ cation. Not sure though, you might get a carbocation...

          It's a "homolytic cleavage"--they split as two radicals:

          H3C-H ---> H3C. + .H

          • Ahh right, I knew that was a possibility from the initiation of Cl. radicals. I thought that the relative electronegativities of the halogens in CFCs was responsible for allowing homolytic fission - I presume that's something else, though, perhaps bond strength.
      • Once radiation breaks the (covalent) bond with one of the (four) hydrogen atoms in the methane molecule, the hydrogen won't last long. Hydrogen is light, floats to the top of the atmosphere, and gets lost into space. Water is at risk too, but it's a really tough molecule and we started with a lot of it (and it freezes and falls back down while it's still low enough in the atmosphere to have some protection from radiation).
        • Re: (Score:3, Informative)

          Well you probably wanted to say intramolecular C-H bond instead of hydrogen bond, which is a kind of intermolecular bonding...

          Hydrogen bonds certainly can be intramolecular. Intramolecular hydrogen bonds are a significant part of what holds a folded protein in its shape.
    • Re: (Score:3, Informative)

      The concept originated in the study of radioactive decay, but applies to many other fields as well, including phenomena which are described by non-exponential decays.

      See http://en.wikipedia.org/wiki/Half-life [wikipedia.org]
    • Raw UV radiation causes methane to convert to more stable water and carbon dioxide.
  • No life? (Score:4, Interesting)

    by Life700MB (930032) on Friday October 06 2006, @06:28AM (#16334557)

    All that looong summary and no mention of the most interesting posibility: that the methane is life-generated by bacteria and the like living under the Martian soil.

    --
    Superb hosting [tinyurl.com] 200GB Storage, 2_TB_ bandwidth, php, mysql, ssh, $7.95
    • Re:No life? (Score:4, Insightful)

      by z0idberg (888892) on Friday October 06 2006, @06:33AM (#16334593)
      I think the point is that the source of methane could potentially have been produced by living organisms but there is no other evidence at all of living organisms. Hence the search for what else could be the source.
      • Re:No life? (Score:4, Insightful)

        by MichaelSmith (789609) on Friday October 06 2006, @06:42AM (#16334629) Homepage Journal
        methane could potentially have been produced by living organisms

        Given that we know the rate of destruction of Methane on Mars we also know the rate of production, which should make it possible to estimate the mass of Methane producing bacteria, assuming that is the source.

        • That would require a great deal of knowledge about the bacteria; mostly their metabolism and food sources.
      • Everybody knows that Martian Methane is produced by Martian cows.
        • But are they happy cows? Did they vote for that guy who came to mars and had his eyes bug out?
      • I think the point is that the source of methane could potentially have been produced by living organisms but there is no other evidence at all of living organisms. Hence the search for what else could be the source.

        Given that the ONLY experiment ever designed to specifically test for life on Mars had a POSITIVE RESULT, I think it's highly misleading to say that there is NO evidence for living organisms on Mars. Remember, just because there is evidence for something doesn't mean that something is true. It

    • There are a number of Mars lander missions planned by NASA and ESA that will try to answer that very question. The new rovers will drill up to 100 cm under the surface and a new generation of chemical analyzers will look at the chemical results from that deep in the soil. It's likely that small microbes could live in the Martian soil using small amounts of water moisture trapped in the soil.
      • Re:No life? (Score:5, Informative)

        by Rei (128717) on Friday October 06 2006, @11:14AM (#16337547) Homepage
        No, it's not likely. Everything that we've come to learn about Martian regolith is that it's highly oxidative -- peroxides, superoxides, etc. Then factor in the problems we've known for a long time -- radiation, temperatures, lack of liquids, etc.

        If there's any life there, it must be extremely different from life on Earth to be able to withstand the oxidative environment. On Earth, Martian regolith would be a disinfectant.

        Besides, volcanism and this new theory aren't the only viable ones for methane production. Serpentization of olivine will do the trick as well. That is to say, if anywhere on the planet there is subsurface water saturated with CO2 in ever-common olivine-rich rock, it will produce methane.
        • Re:No life? (Score:5, Informative)

          by SirBruce (679714) on Friday October 06 2006, @12:21PM (#16338591) Homepage
          Ahhh, the old "highly oxidative" argument.

          In truth, there has never been a test on a Martian lander designed to either confirm or identify the nature of this hypothetical strong oxidant. While there are theories that suggest that UV light should create such oxidants, the presence of a higly oxidant Martian surface has never been confirmed by experiment. Rather, it has been invoked as an EXPLANATION why certain other results, such a the Viking LRE, must be faulty.

          To date, no subsequent Mars probe has produced data that points to a strong global surface oxidation beyond the usual culprits of H20 and CO2 (which account for the rust).

          Bruce
          • Re: (Score:3, Informative)

            Not only UV, but also dust devils. Experiments on simulated dust devils show that they produce about 200 times more H2O2 than UV does.

            H2O2 *has* been detected on Mars. In 2003, the IR TEXES spectrometer team detected 20-50 ppb of H2O2 in the atmosphere. The James Clerk Maxwell Telescope confirmed this. Since it doesn't last long in the atmosphere, this means that it's constantly being produced. H2O2 bound to dust particles would end up in the soil, so this observation is consistant with theory.

            In short
  • It just goes to show that Martians like beans... A lot.
      • The more you toot,
        The better you feel,
        So be sure to eat beans
        With every meal!
        • Baked, beans,
          Are good for the heart.
          Baked, beans,
          Make you fart.
          The more you fart,
          The better you feel,
          So eat, Baked beans,
          For every meal!

          There, corrected it for you.
  • Good science (Score:5, Insightful)

    by Da3vid (926771) on Friday October 06 2006, @07:23AM (#16334863)
    "'If Mauna Loa is a valid terrestrial analog, our findings suggest that volcanic activity is not a significant source of methane to the Martian atmosphere.'"

    Man, I wish more of our scientific quotes sounded like this one. It lays it out straight and simple. Here is our source of info: analogy with Mauna Loa. Here is our assumption: we can project info from it onto Olympus Mons. Here is our conclusion: there is something else other than volcanic activity producing methane on Mars. I like how all that info was neatly packaged into a simple sentence. I also like how he admits the assumption... if. The thing that comes to mind are all the dinosaur shows explaining their day to day lives, zodiac signs and favorite take-out places.
  • Auspiciously quiet?
  • Thomas Gold (Score:3, Interesting)

    by BenJeremy (181303) on Friday October 06 2006, @08:48AM (#16335661)
    Didn't Thomas Gold postulate that we'd find lots of methane on Mars? He had many intriguing theories on "deep life" - and recent evidence of "replenishment" of petroleum reserves, IIRC, while puzzling to geologists following the standard theories, would not have been a mystery to him.
    • Did Gold predict methane on Mars? Most likely. He's predicted it just about everywhere else. Mostly, he's been wrong. One can make a pretty good case that if you shoot enough arrows you're bound to hit something occasionally.
    • Didn't Thomas Gold postulate that we'd find lots of methane on Mars? He had many intriguing theories on "deep life" - and recent evidence of "replenishment" of petroleum reserves, IIRC, while puzzling to geologists following the standard theories, would not have been a mystery to him.

      Dr. Gold was also convinced that the Moon was covered in dust many meters deep - after the Surveyor landings showed that to be incorrect, he changed his belief to 'the moon is covered in dust with a crust just thick enough to

    • Re:Biggest Volcano (Score:4, Informative)

      by tomhudson (43916) <hudson@videotQUOTEron.ca minus punct> on Friday October 06 2006, @06:47AM (#16334661) Journal

      The solar system's biggest volcano is Loki on Jupiter's moon Io.

      Nope. Its "the most powerful". While they might cover the same surface area, Olympus Mons stands much higher.

      • While they might cover the same surface area, Olympus Mons stands much higher.

        Of course the real business with a volcano happens under ground and we don't know much about this part of either volcano.

      • Nope. Its "the most powerful". While they might cover the same surface area, Olympus Mons stands much higher.

        True, Olympus Mons [solarviews.com] is absolutely huge. The summit is at 27 kilometres above the mean surface level on Mars and it covers a surface area the size of Arizona. It would be fantastic to be able to stand on that summit and enjoy the view.
    • Re: (Score:2, Insightful)

      Uhm. Since always? Science is the whole idea of making a (thought out or not) statement, and then setting about disproving it. If you fail to disprove it, you end up with the 'last option is that it's true' idea.
    • Re: (Score:3, Interesting)

      I agree totally and welcome our new bacterial overlords.

      Science, particularly in the US, seems to be slipping back into its old habits. Dogma reigns supreme and dissident voices are quashed without cause or concern simply for going against the norm.

      A friend of mine used to argue that science was no different from religion, and scientists a new breed of priest. I hated his argument, but lately I have had to question how valid that may be.

      The question to ask then is, why would life on Mars recieve such scathi
      • Re: (Score:2, Interesting)

        by Anonymous Coward
        > "Who benefits from from perpetuating the belief that there can be no life on Mars?"

        The most logical answer is just "common sense." It's been universally accepted that Mars is a barren planet for hundreds of years (mice in telescopes and canals aside). That builds a lot of inertia to overcome by anyone that wants to come along and change that belief.

        The other possibility is a roadblock that The Mars Society and The Mars Underground ran into a couple of years back. Their goal is to get NASA to Mars an
      • Re: (Score:2, Insightful)

        It's called: Remarkable claims require remarkable evidence.

        Science isn't about believing anything is possible until proved otherwise. I think many scientists would agree that it's possible there is or was life on Mars. But life evolving independently anywhere other than Earth would be a major breakthrough for science, so they want to be very careful about claiming it until it is really, unquestionably proved. IMO this is just good science.

      • Surely if one applies occams razor to the question, we must believe strongly in the possibility that Mars does indeed have the capability of supporting some forms of primitive life.

        Correct me if I'm wrong, but I think this is a misuse of Occam's Razor. The principle basically says that the solution that requires the fewest number of variables is most likely to be correct. So in this case, the existance of life on mars is a big "extra", if the presence of methane can be explained without it.

    • by Eunuchswear (210685) on Friday October 06 2006, @07:37AM (#16334987) Journal
      Ok,

      1. just turning C02 + H2O + energy -> CH4 + ...
        would be seriously dumb as CH4 is a much more potent greenhouse gas than C02, and stockpiling it would harder than just stockpiling the CO2 in the first place.
      2. and turning C02 + H20 + energy -> CH4 then burning the CH4 to get C02 + energy is just a nice way of wasting energy.
      3. You're not talking about a power source, just an expensive and dangerous power transmission medium.
      4. And finaly, what on earth do you mean by fragile biological processes? Artificial processes are way more fragile than biological ones.