Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
Space Science

The Mystery of the Missing Methane 98

Hugh Pickens writes "Astrobiology Magazine reports that NASA's Spitzer Space Telescope has discovered something odd about GJ 436b, a planet about the size of Neptune located 33 light-years away, circling the star Gliese 436. The mystery? GJ 436b lacks methane, an ingredient common to many of the planets in our solar system. Methane is present on our life-bearing planet, manufactured primarily by microbes living in cows, and all of the giant planets in our solar system have methane too, despite their lack of cows. Spitzer was able to detect the faint glow of GJ 436b by watching it slip behind its star, an event called a secondary eclipse. As the planet disappears, the total light observed from the star system drops, and the diference is then measured to find the brightness of the planet at various wavelengths. Eventually, a larger space telescope could use the same kind of technique to search smaller, Earth-like worlds for methane and other chemical signs of life, such as water, oxygen and carbon dioxide. Adam Showman, a planetary scientist at the University of Arizona, says the 'provocative result' raises questions about the evolution of this planet, as well as the possibility that its atmosphere might represent an entirely new class of atmospheres that has never been explored."
This discussion has been archived. No new comments can be posted.

The Mystery of the Missing Methane

Comments Filter:
  • by countertrolling ( 1585477 ) on Sunday April 25, 2010 @01:29PM (#31975962) Journal

    We don't know that for sure. We haven't been to the surface of any of these planets. I believe more study is needed.

  • Obvious solution (Score:3, Interesting)

    by maxwell demon ( 590494 ) on Sunday April 25, 2010 @01:30PM (#31975974) Journal

    Methane is an important source of energy. Obviously there's an alien species which has used up all the methane from that planet.

    • by Z00L00K ( 682162 )

      Even if the aliens are bacteria or similar it's an interesting thought. Methane can be used as a fuel and microorganisms may have it as a food source.

      And if there are microorganisms there is always the possibility that there is life. However the light from the star may also be intense enough to crack up the methane molecules resulting in other types of compounds.

      There may be other explanations too - the planet may have suffered some disturbing events where it lost a major part of it's atmosphere.

    • Re:Obvious solution (Score:5, Interesting)

      by reverseengineer ( 580922 ) on Sunday April 25, 2010 @04:39PM (#31977760)
      The reaction being looked at here is interesting because it is the same reaction used on Earth in the steam reforming of methane to produce hydrogen, with the same equilibrium issues. Methane (or many other hydrocarbons) can be reacted with water vapor to produce carbon monoxide and hydrogen. However, this reaction is not going to proceed forward under normal atmospheric conditions on Earth, and at least was not expected to proceed forward under the conditions of GJ 436b. The reaction needs enough energy put in to break apart methane and water molecules before their components can be recombined to form CO and hydrogen. In the absence of catalysts, you should expect this step to occur at temperatures no lower than around 920K, while GJ 436b is believed to be at 800K.

      We can look at some of the possibilities of what could be happening on GJ 436b:
      CH4 + H2O is in equilibrium with CO + 3 H2 (with a change in enthalpy of +206kJ/mol)
      1. The temperature of GJ 436b could be higher than what is measured. If the temperature is actually above around 920K, then the necessary activation energy is present to get this reaction headed to the right side of the equation. This solves the mystery, but then opens a new mystery of why the temperature measurement is off by over 100K.
      2. A reaction product is rapidly being taken away after formation. If either carbon monoxide or hydrogen were somehow continuously removed from the site of the reaction, the reaction equilibrium would keep favoring the generation of more CO and H2 rather than reversing to make more methane and water. This is what the suggestion of "vertical mixing" is alluding to: if the "steam methane reforming" reaction is isolated to one region of the atmosphere, but the reaction products rapidly migrate to another, then the reaction equilibrium makes sense.
      3. When steam reforming of methane is done as an industrial process on Earth, the reactions are carried out at temperatures of about 700-800K, right around the temperature of GJ 436b. The necessary activation energy is lowered by metal catalysts (usually nickel) Could the interaction of the atmosphere with the rocky core be catalyzing this reaction? It's unlikely that there's enough surface area to transform the whole atmosphere in this manner, but it's an intriguing possibility.
      • Re: (Score:3, Informative)

        I found a nice little illustration of the effect temperature has on the equilibrium of this reaction here. [davidson.edu] The calculation is actually for the related reaction using carbon (as coke) instead of methane, but the equilibrium constants are about equal for the temperatures discussed here. At atmospheric conditions on Earth, the equilibrium can be considered as shifted completely to the left. Virtually no carbon monoxide is produced from this reaction at temperatures less than about 600K. At a temperature of
        • by Intron ( 870560 )
          A factor of 7000 is not too much different than a slightly different Earth might look. Our actual mix of 387 ppmv CO2 vs. 1.79 ppmv CH4 is partly due to the afore-mentioned cow population. Maybe it's a similar planet that never evolved Ray Kroc.
  • by eldavojohn ( 898314 ) * <(eldavojohn) (at) (gmail.com)> on Sunday April 25, 2010 @01:30PM (#31975982) Journal

    Methane is present on our life-bearing planet, manufactured primarily by microbes living in cows, and all of the giant planets in our solar system have methane too, despite their lack of cows.

    Why are cows focused on so much when it comes to methane? The only study I can find lists livestock making up only 19% as a source of atmospheric methane [wikipedia.org]. That's little more than our industrial energy sector production and about half as much as our wetlands produce. From NOAA [noaa.gov]:

    Rapidly growing industrialization in Asia and rising wetland emissions in the Arctic and tropics are the most likely causes of the recent methane increase, said scientist Ed Dlugokencky from NOAA's Earth System Research Laboratory.

    • When we drill the borehole to the center of the earth, we will find it's cows all the way down

    • Re: (Score:3, Interesting)

      Why are cows focused on so much when it comes to methane?

      Because if they focused on rice, it wouldn't give a good argument for vegetarians. :-)

      • by MacDork ( 560499 )

        Why are cows focused on so much when it comes to methane?

        Because if they focused on rice, it wouldn't give a good argument for vegetarians. :-)

        Or tree huggers trying to "Save our precious wetlands!"

      • by thijsh ( 910751 )
        They already invented methane-free cows, couldn't they also create methane-free rice?

        Probably... but the vega-hippies still would complain since it is 'bio-engineered'... Most would rather have 2 billion people starve than have bio-engineered crops (even though I presume most of these don't even know about the fact that we can only feed 4 billion if we only produce biological crops, they just go with the rest of the hippie nature crowd without understanding what's at stake).

        P.S. Repost for accidental
        • ... but the vega-hippies still would complain

          Actually we dumped all hippies in a place called "Sanaf Aran Siskh' oh" millenia ago; they complained too much.


          Microsoft car: We have noticed you are in the process of crashing. Would you want your airbags deployed?

    • by sznupi ( 719324 )

      As a guess, because it's the most ridiculous contribution (nonetheless contributing to the feedback, most notably with arctic wetlands), the easiest to deal with...yet we still fail to do it. And that's with all the abundance of other tasty animals out there.

      • Yeah but cow's eat grass, and digest, through symbiosis with the evil methane bacteria, cellulose. Only ruminants do that, and all ruminants produce methane. Any other animals can't get the same amount of energy grazing off scrub brush.
        • by sznupi ( 719324 ) on Sunday April 25, 2010 @02:39PM (#31976586) Homepage

          Cows eating grass, outside...where have you seen that? O_o

          In seriousness, that's not a showstopper; especially if reduced availability of meat would, for many people, actually increase their health (I don't advocate not eating meat, I do it myself; but too many people consume ridiculous amounts of it these days, having fallen in the trap of one old adaptation - "if there's some meat around, eat it!")

          • Cows eating grass, outside...where have you seen that? O_o


          • Cows eating grass, outside...where have you seen that? O_o

            It’s called south south America. Or Switzerland. Look it up! ^^
            (Seriously, Switzerland is cow heaven right there. So insanely beautiful!)

            • by Creepy ( 93888 )

              True South America, as Brazil is, in fact, the world leader in beef exports, followed by Australia. I recall Argentina and Uruguay and several Central American countries are in the top 10 as well. Then there's India, which was still exporting more beef than the United States last time I checked (yes, sacred cow country is #3 in exports) I don't think Europe even has a country in the top 10, but maybe as a whole they get in there. That is far more than I really needed to know, picked up from my brother-i

      • If we were to raise and eat other animals in the same quantities as we raise and eat cows, I'm sure we'd have other "problems" as well. Exactly what animal do you suggest as a replacement for cattle?

    • NASA is ready to launch some cows in space to help GJ 436b !
    • Why So Much Focus on Cows?

      'coz they make delicious burgers, and therefore vital to any self-respecting westerner. Please try and keep up with the conversation.

    • Because cows are funnier than decaying peat moss, OK? Now make a cow joke!

    • No one can resist a fart joke
  • Just let me finish my burrito...
  • Adam Showman, a planetary scientist at the University of Arizona, says the 'provocative result' raises questions about the evolution of this planet...

    Adam Showman talking about a provocative result eh? Who is surprised? I mean what else could you expect from the father of all show men?

  • Hello Earth,

    This is your distant neighbor GJ-436b. We need some cows immediately, for we are completely out of methane. Without methane, we cannot create barbecue lighters, and thus no Forth of Snibbej parties.

    We have made some financial arrangements with a Nigerian prince who has agreed to...

  • From TFA I take it that such a kind of atmosphere is not in chemical equilibrium given its pressure and temperature. The interesting question is what actually causes such disequilibrium conditions on a planetary scale. Massive tectonic activity? Constant bombardment with a metric shitload of comets altering the composition? Life?
  • Sign of life? (Score:4, Insightful)

    by JoshuaZ ( 1134087 ) on Sunday April 25, 2010 @01:43PM (#31976090) Homepage
    Is this a sign of life? The calculations for how much methane should be in the atmosphere are based off what results in a chemical equilibrium. However, active metabolic entities (life) can move things very far off equilibrium. Thus, for example, Earth has a lot more oxygen in the atmosphere than would be expected from a simple set of equilibrium calculations. So, an observer could tentatively conclude that something weird, such as plant life, might be about. This imbalance between the expected and observed methane levels may be due to extraterrestrial life.
  • See, we shouldn't have sent that message, "HEY GUYS WE GOTS METHANE!" In another few thousand years they're coming for our cows!

  • Maybe they invented non-farting cows.

  • The planetary atmosphere is at disequilibrium for a single observation. Because I observe during (or just after) a volcanic eruption or a meteor impact or a CME or a nuclear war ;) am I to assume it's always that way?
    • Re: (Score:1, Informative)

      by Anonymous Coward

      Actually it was six observation at six different infrared wavelenghts over a six month period.

  • "despite the lack of cows" - I like it. It's a good analogy. However, cows would need oxygen too. And it's not the cows' fault!
  • It's a lack of Taco Bell franchises.

  • by 3seas ( 184403 ) on Sunday April 25, 2010 @02:14PM (#31976374) Homepage Journal

    The Aliens took it on their way here. They needed the fuel resource. See Steven Hawkins story about not talking to the aliens when the get here.

    BTW, the earth is leaking Methane [discovery.com] as its been discovered that it wasn't cows causing increased methane here.

    • by sznupi ( 719324 )

      Oh c'mon, it's not like we have any second thoughts about actually probing the cows (and measuring how much methane they emit)

  • Where are Scoob and Shag when you need them?
  • At the least we know they fart.

  • by fizzup ( 788545 ) on Sunday April 25, 2010 @05:11PM (#31978042)

    This planet has got to be populated by nothing but women. Nobody farts!

  • "...that its atmosphere might represent an entirely new class of atmospheres that has never been explored." Reminds me of an old quote: "The Universe is not only stranger than we imagine, it's stranger than we CAN imagine."
  • "Alien Cows do not Produce Methane"
  • why the cows are focused so much? Window [solarcontrolfilmsinc.com]
  • I submitted that one several days ago!

    Bah! Humbug!

Executive ability is deciding quickly and getting somebody else to do the work. -- John G. Pollard