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Hydrocarbon Rain Swells Titan's Lakes

Posted by kdawson on from the singin'-in-the-methane dept.

Rob Carr writes "According to the Cassini team, 'Recent images of Titan from NASA's Cassini spacecraft affirm the presence of lakes of liquid hydrocarbons by capturing changes in the lakes brought on by rainfall.' The northern lakes are now larger following a period in which hydrocarbon clouds covered their skies. (The research was published in the journal Geophysical Research Letters.) This change adds to the evidence these areas are indeed hydrocarbon lakes. But this discovery raises several more questions: where is the methane in the atmosphere coming from, and how long can this complex hydrocarbon cycle on Titan go on? The new evidence emphasizes the need for another mission to Titan."

38 of 110 comments (clear)

  1. inb4... by Anonymous Coward · · Score: 4, Funny

    inb4 people suggesting that we transport hydrocarbons from Titan to use as fuels on earth.

    1. Re:inb4... by MrNaz · · Score: 2, Funny

      I think the real issue is Republicans suggesting that we need to send in the armed forces to liberate the oppressed Titanians from their evil terrorism-supporting dictator.

      --
      I hate printers.
  2. Another "planet" with resources... by Anonymous Coward · · Score: 4, Funny

    ...to wage war over. It'll happen.

    1. Re:Another "planet" with resources... by Anonymous Coward · · Score: 5, Insightful

      You must be a nut to think that "Dubya" will be a single, isolated incident in the history of mankind.

    2. Re:Another "planet" with resources... by Anonymous Coward · · Score: 2, Insightful

      ...to wage war over. It'll happen.

      It is kinda disappointing to read about interesting places in the solar system and realize that war or no, our race will only be interested enough to get there when the profit motive is clear.

  3. Now all we need... by MichaelSmith · · Score: 4, Funny

    ...is fossil oxygen in liquid form reachable by drilling.

    --
    http://michaelsmith.id.au
    1. Re:Now all we need... by jmv · · Score: 2, Interesting

      The funny thing is that doing that might cause global cooling because CO2 is much less effective at trapping heat than methane.

      --
      Opus: the Swiss army knife of audio codec
    2. Re:Now all we need... by MichaelSmith · · Score: 2, Interesting

      Yes I though about that. CO2 will actually have zero warming effect because it is a solid at Titan surface temperatures. Environmentalists may complain about carbon fog.

      --
      http://michaelsmith.id.au
  4. Obvious source of the methane... by jimbudncl · · Score: 5, Funny

    Uranus.

    1. Re:Obvious source of the methane... by CarpetShark · · Score: 2, Funny

      Obvious source of the methane...
      Uranus

      No, Uranus.

    2. Re:Obvious source of the methane... by TheCybernator · · Score: 2, Interesting

      HydroCarbons and Titan and only one Uranus joke? it must be Sunday today!

      --
      Eclipse PDE and Me
  5. Nothing New ! by AmigaMMC · · Score: 4, Interesting

    I had already read that in Stephen Baxter's novel "Titan" - That guy is always so right! :)

  6. source http://www.esa.int by Saysys · · Score: 5, Interesting

    The question of how much liquid is on the surface is an important one because methane is a strong greenhouse gas on Titan as well as on Earth, but there is much more of it on Titan. If all the observed liquid on Titan is methane, it would only last a few million years, because as methane escapes into Titan's atmosphere, it breaks down and escapes into space.

    If the methane were to run out, Titan could become much colder. Scientists believe that methane might be supplied to the atmosphere by venting from the interior in cryovolcanic eruptions. If so, the amount of methane, and the temperature on Titan, may have fluctuated dramatically in Titan's past.

    1. Re:source http://www.esa.int by Cally · · Score: 5, Informative

      I actually shelled out $9 to read the Geophysical Review Letters paper (I take my armchair planetary science geekery pretty seriously, but sadly not enough to justify journal subscriptions.) One possibility mentioned is sub-surface reservoirs as a possible source keeping the atmosphere topped up. (Note that unlike on earth, where methane has an atmospheric lifetime measured in weeks, at Titan it's millions or tens of millions of years.) Another interesting thing is the description of GCMs (global circulation models) and evidence of classical, earth-style Hadley cells, a major feature of earth's climate.

      --
      "None are more hopelessly enslaved than those who falsely believe they are free." -- Goethe
    2. Re:source http://www.esa.int by ogdenk · · Score: 3, Interesting

      it would only last a few million years, because as methane escapes into Titan's atmosphere, it breaks down and escapes into space.

      Does that suggest that Titan itself is rather young compared to the planet it orbits? Or was Titan much more active and possibly larger 50 million years ago?

      I'm not a geologist or astrophysicist so I'm rather ignorant in this department.

    3. Re:source http://www.esa.int by khallow · · Score: 3, Insightful

      If all the observed liquid on Titan is methane, it would only last a few million years, because as methane escapes into Titan's atmosphere, it breaks down and escapes into space.

      Doesn't sound right. At a glance, from Wikipedia, if I assume methane is an ideal gas, the average velocity of methane gas is roughly:

      v = sqrt(3kT/M).

      Here, T = 94K, k =1.38*10^-23 m^2 kg/ (s^2 K), and M = 2.32*10^-26 kg (mass of a molecule of methane). Crunching the numbers I get that the average velocity of methane is roughly 400 m/s. In comparison, escape velocity from Titan's surface is 2.65 km/s. Titan's radius is more than 2,500 km. As I understand it, escape velocity scales as the square root of radius. So you'd have to be above 6,000 km radius in order to get escape velocities down to 400 m/s. But the atmosphere is nowhere near 3500 km thick. I just don't think this is a credible option for methane loss.

      The second possibility is decomposition of methane due to UV light. Using the above formula, H2, which has a seventh the mass of methane has an average velocity of under 1100 m/s. That's not escape velocity until you're at a radius of 4,000 km. Plus, being on average 9.5 AU from the Sun, means that solar influx is far lower than on Earth. So you get something like 15 W/m^2 compared to 1300 W/m^2 at Earth. Hydrogen loss on Earth is pretty minuscule too. Plus, we're probably well below methane's freezing point by the time we get to the upper atmosphere (which I'd guess is probably mostly nitrogen with traces of other molecules). So just like water vapor freezes at high altitudes, I imagine that little methane reaches the upper atmosphere.

      Solar wind doesn't play a role since apparently Titan is just inside Saturn's magnetosphere. The linked paper indicates that the dominate mass wasting process is the atmosphere's interaction with Saturn's magnetosphere.

      To summarize, I just don't see the process that's going to eliminate most methane from Titan's atmosphere on the order of millions of years.

    4. Re:source http://www.esa.int by AaronLawrence · · Score: 3, Informative

      As I read the FA, the methane from the atmosphere is lost to the surface, not into space. It evaporates from lakes but rains back again and forms "methane derived haze particles"... they think these two forms are more than evaporation... ergo there should be not much methane in the atmosphere over the long term.
      This point wasn't terribly clear in the article however.

      --
      For every expert, there is an equal and opposite expert. - Arthur C. Clarke
    5. Re:source http://www.esa.int by WalkingWounded · · Score: 2, Insightful

      The critical thing you have there is that you are calculating the average velocity, not the fraction that is trotting along at > 2.65km/s. That will be e^(- (2.65km/s / 400m/s)^2), or about 1 in 1e19 methane molecules will have escape velocity. In the case of H2 that'd be a full 0.3% of molecules having escape velocity.

      The actual loss rate will depend on a few other things, such as the mean free path of the molecules (i.e. how likely are they to bump into another before escaping, and how frequently they get their energies reset to a function of the average).

      Look up Boltzmann distributions for more.

    6. Re:source http://www.esa.int by deglr6328 · · Score: 4, Informative

      jeez dude, you should really search, uhmmm this thing called the interwebs before letting yourself get raped by the ABSURDLY high prices these journals demand for a single paper! look. here. FREE! If you're an American YOU ALREADY PAID FOR THIS research. that's why it's on a NASA site for free. even when it isn't taxpayer funded research it's still VERY common to see a paper from a peer reviewed journal also up on a professor's personal page as a preprint or whatever.

      --
      - "Hear that?! The percolations are imminent! Cease your ingress!"
    7. Re:source http://www.esa.int by wizardforce · · Score: 4, Informative

      A few points of contention:
      1) methane is not an ideal gas at the average temperature of Titan.
      2) your velocity is root mean square not the velocity of all methane molecules in the atmosphere. The velocity of gas molecules is that of a bell curve not a concrete quantized single quantity. The fact is that although small by comparison, there's going to be a few methane molecules that have the velocity required to escape Titan's gravity no matter what the temperature. Granted the number of methane molecules capable of escaping increases dramatically with temperature... there should be enough that can escape to make millions or billions of years a fair approximation as to the average length of time a methane molecule stays bound in Titan's gravity well. THis is of course neglecting ionization of methane molecules caused by external radiation sources which reduce the lifetime of methane molecules captured.

      --
      Sigs are too short to say anything truly profound so read the above post instead.
  7. Re:bad modding by peragrin · · Score: 2, Insightful

    You 99%correct. Wars are normally fought over resources. It was land as farms weren't that good. Near Future wars will be over oil. Howver far into the future the mainstay resources will shift. Currently oil literally drives us. It used to be food(people, horses ,etc). It will probably be the element that enables FTL.

    --
    i thought once I was found, but it was only a dream.
  8. Re:bad modding by Slur · · Score: 4, Funny

    It will probably be the element that enables FTL.

    Imagination?

    --
    -- thinkyhead software and media
  9. Re:HOORAY by 278MorkandMindy · · Score: 2, Funny

    That would be cool, titan on fire in orbit, never have a night!
    That IS what you were talking about???

  10. Re:bad modding by tukkayoot · · Score: 2, Insightful

    Howver far into the future the mainstay resources will shift. Currently oil literally drives us. It used to be food(people, horses ,etc). It will probably be the element that enables FTL.

    FTL may not even be possible. I think our likely "far future" will be shaped by the development of strong artificial intelligence and the realization of a technological singularity. It's hard to predict what will follow that, almost by definition ... but it's hard for me to imagine that it will involve humans fighting wars over material resources. Which is not to say such conflict won't be replaced by something even more appalling.

  11. Space Oil Tanker... by meson2439 · · Score: 2, Funny

    Methane in Titan will be the start for a new age of space exploration. Since alternative energy still sucks, we might just siphon all of Titan methane to earth. Titan is just a few planet further from earth.

    The future oil tanker might not look like death star but the size should be comparable. It will need to carry a lot of oil due to the infrequent trip (Since lightspeed travel is impossible).

    1. Re:Space Oil Tanker... by Fjandr · · Score: 3, Insightful

      So not only do we fill our atmosphere with the CO2 produced from burning our own hydrocarbons, but then we fill our atmosphere with the CO2 produced by burning an entire other planet's worth of hydrocarbons. Brilliant!

      I suppose we could build sequestration plants on Titan and pump all the exhaust back up there though.

    2. Re:Space Oil Tanker... by NeverVotedBush · · Score: 3, Interesting

      I'm wondering how you land all that methane back on earth.

      It may be a liquid on Titan, but as you get it back closer to earth and let the sun start to warm the skin of the spaceship, it's going to start turning into gas and take up a lot more volume.

      But let's assume you figure out a way to keep it liquid. How do you get it back down to earth? A space shuttle sized spacecraft is only going to be able to bring back a tanker truckload or so. You'll use much more energy than that just to relaunch some spacecraft to go get more.

      It's a terrible idea anyway, but also impractical.

  12. Re:bad modding by techno-vampire · · Score: 3, Informative

    The official reason for the Crusades may have been religion, but it's amazing how many crusading knights ended up as major land owners in the Holy Land. The Pacific section of WW II was all about resources, as Japan's Greater East Asian Co-Prosperity Sphere should make clear. Asia ruled by Asians instead of Europeans was just a veneer to cover over the way the Japanese were grabbing control of the iron, coal and oil their economy needed, and the rice to feed their people.

    --
    Good, inexpensive web hosting
  13. Abiogenic Hydrocarbons by PPH · · Score: 3, Interesting

    The question of where all of Titan's hydrocarbons come from might cause the theory of abiogenic petroleum to be revisited. Much to the chagrin of the peak oil proponents.

    --
    Have gnu, will travel.
  14. Re:bad modding by Fjandr · · Score: 3, Informative

    I wouldn't say wars are driven by a need for resources so much as a desire for them by those in power. Power/control could be considered a resource for those driven by desire for more of it.

    Those brutally nasty wars based on warped and twisted religious/political/ethnic ideology funneled massive profits into the hands of supporters, be they from looting during the Crusades or manufacturing contracts during contemporary times. A war for resources is not so much about helping a population in general as about enriching those in power. I can't think offhand of a war that has occurred where that was not true.

    All those wars you cited ended up enriching the antagonist victors (the very definition of "a war for resources"), and would have enriched those antagonists who lost had they instead emerged victorious.

  15. Wouldn't it be crazy... by Metasquares · · Score: 2, Interesting

    If there were life on Titan using hydrocarbons as we use water?

    I'm sure there are several reasons why this is chemically infeasible, but I just wanted to throw the possibility out there. We tend to get into bad habits of assuming that extraterrestrial life would function just as terrestrial life would.

    1. Re:Wouldn't it be crazy... by NeverVotedBush · · Score: 4, Funny

      At least we would never have to worry about being invaded. A flamethrower would be the ultimate weapon against them in our atmosphere.

    2. Re:Wouldn't it be crazy... by TapeCutter · · Score: 2, Funny

      "burning is probably how they reproduce"

      So you're saying Titan porn is hot?

      --
      And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
    3. Re:Wouldn't it be crazy... by az-saguaro · · Score: 4, Informative

      The reason that Titan is of such great interest (aside form the fact that Cassini-Huygens is giving us reams of data that we could never see from Earth), is that its chemistry is considered comparable to Earth in the pre-biotic eras. Our current hydro-nitrox environment evolved slowly due to abiotic and biotic chemistry starting with something that may be similar to what Titan now has. Somewhere in the distant past, biotic chemistry had to start in something that had high methane or other hydrocarbons. Even now, earth has extremophile niche organisms, some of which might well survive conditions comparable to Titan, to a degree.

      But, there are crucial differences. Biotic chemistry and the formation and evolution of life depend on complex molecules interacting in a solution. The ionic or soluble molecules, with nitrogen, oxygen, and sulfur, as well as C-H, which define life as we understand it, need water as the solvent. On Titan, it may exist at some thermal boundary far below the surface, but not at the top (the same reason that Jupiter's Europa, which does have water and ionic solutions in oceans near the surface is of such great interest as to the possibility of life).

      Titan is probably too cold to permit evolution. Atmospheric ionizations, lightening, deep geothermal chemistry, and so on may indeed have generated some biotic precursors - complex organics, amino acids, carbohydrates, or nucleic acids - but the chances of them being able to interact the gazillions of times needed to randomly find stable and regenerative molecules is unlikely at its ambient temperatures.

      However, the possibility that, at the right temperatures and thermodynamics, that these molecules could assemble and evolve in a methane solvent, is not beyond theoretical possibility, as long as enough nitrogen, oxygen, other atoms, (water), and energy are there to evolve the complexity of the molecules. This is what is presumed to have happened on earth.

      It is possible that current Titanic atmospheric chemistry is converting CH4 into larger hydrocarbons and other molecules, which would sequester the methane, making it "disappear". Since these molecules would be denser than methane, they might be below the observable surface, and we would not know about them. It is possible though that far enough below, where warmer, that the chemistry has become very complex, possibly pre-biotic, or perhaps even biotic. Of course, that is the point of this original article, that the hydrocarbons are there in mass quantities, so some sort of long term chemistry is going on.

      It would be interesting to take Titan's chemistry, as we have learned about it from Cassini-Huygens, put it in a laboratory bioreactor, adds some "lightening", heat, and so forth, and see what happens. In an old original Outer Limits episode from the 60's, they did just that, and some spooky creature evolved - how prescient!

    4. Re:Wouldn't it be crazy... by Rob+Carr · · Score: 3, Interesting
      I did a calculation a while back, assuming that the rule of thumb on earth held on Titan: reaction rates drop 50% for 10 degree drop in temperature. Using an estimate for the time required to develop life on Earth, the calc indicated it would be unlikely to have developed on Titan within the lifetime of the universe.

      Of course, there are quite a few problems with that analysis:
      1. Different chemical system might make the reaction rate different.
      2. That's a long way to push a law that obviously fails at the freezing temp of water.
      3. If life formed on Earth much sooner than the estimate I used, again the number might be off.

      Then again, what would be the information molecule? DNA is a polymer with subunits that can encode information. There aren't a lot of methane-soluble polymers that would make for good information storage.

      Then again, maybe I'm not thinking outside the box and something radically different would be used.

      Life on Titan is unlikely, but I think we'd be making a big mistake assuming it's impossible.

      --
      This sig seemed like a good idea at the time....
  16. Re:New NASA Exploration Policy: by Sebilrazen · · Score: 2, Funny

    NASA press release headlines- NASA Excepts New Mission: Drill Baby Drill!

    Actually, since they're easily accessible in the form of lakes on the surface wouldn't it be easier to Suck baby, suck?

    --
    "There are no facts, only interpretations." --Friedrich Nietzsche.
  17. Re:bad modding by TapeCutter · · Score: 3, Informative

    I think you have it upside down, resouces are the PRIME reason regardless of any percieved 'need'. When you talk about enforcing "ideology" you are talking about political/religious control of a particular territory and consequently all the resouces within it.

    Wars are never just between the two sides in the headlines, there are all sorts of factions at all sorts of levels. The underlying motivation for war comes from our shared territorial instincts. I'm sure priests, politicians and crusaders would disagree but IMHO religion and politics is just the sales pitch.

    --
    And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
  18. American Rebellion by argent · · Score: 2, Insightful

    American revolution - not resources (at least not entirely, Britain probably did want access to North American resources)

    It was totally about resources - the American colonies taking control of the sugar/rum/slave trade triangle from Britain.

    And don't forget Bush's little oil war.