Methane-Based Life Possible On Titan

ratamacue0 sent me this interesting Slashdot post: Methane-Based Life Possible On Titan – Slashdot.

Randym writes:

With the simultaneous announcement of a possible nitrogen-based, cell-like structure allowing life outside the “liquid water zone” (but within a methane atmosphere) announced by researchers at Cornell (academic paper) and the mystery of fluctuating methane levels on Marsraising the possibility of methane-respiring life, there now exists the possibility of a whole new branch of the tree of life that does not rely on either carbon or oxygen for respiration. We may find evidence of such life here on Earth down in the mantle where “traditional” life cannot survive, but where bacteria has evolved to live off hydrocarbons like methane and benzene.

There’s a lot in this post, all relating to life and methane.  The first is about a study of possible life that might exist in liquid methane (instead of water), which is a possibility in the outer solar system, notably on Titan, a moon of Saturn and the largest one in the solar system.  The average temperature on Titan is about -179 ºC, below the boiling point of methane.  On Titan, methane may flow like water does on Earth, in rivers and lakes.

The idea that there may be methane life in the universe has been around for a while.  The new model seems to lend some support to the idea, but I think it’s important to understand that this is only a hypothetical model.  If methane based life does exist on Titan, I wonder at what stage it would be in its evolution, since life is chemistry, and chemistry at -179 °C (94K) seems like it’s going to flow a lot slower than chemistry at 15 °C (288K).  If there is life on Titan, I think it’s likely still in the relatively early stages.

Mars is cold by our standards, but it’s not far enough from the sun to be cold enough for liquid methane.  Methane is a gas there, just like it is here.  My understanding is that the significance of methane there may be as a possible waste or by-product from some kind of life, much as it is from some life on Earth.  The methane on Mars may still be from non-living natural processes, like volcanoes.  Only time will tell.

The article on life in the lower levels of Earth’s crust is interesting.  I think it got included here because that life may feed on chemicals like methane.  Again, this is different than what’s being envisioned as a possibility for life on Titan, but still pretty fascinating, particularly the possibility that life may permeate down into Earth’s upper mantle.

I think all of this goes to show that we have reasons to believe that life can exist in a wide variety of environments, and that only looking for it in narrow habitat zones may be too limiting.  Personally, given the wide variety of what we call “life” here on Earth, I suspect that when we do find the first extraterrestrial life, it may well challenge our very conception of what life is.  We may end up debating whether or not it actually is life, or just some kind of previously unknown complex chemical processes.

24 thoughts on “Methane-Based Life Possible On Titan

  1. The energy and temperature considerations would certainly make life forms quite different from us. Our sense of personal time, our reaction times, our thought times, are all based on chemical processes, The speed of those depends, in part, on the heat in the system. Freezers preserve our meat and our batteries due to the slowed down chemical reactions. What makes places like Europa intriguing is the heat provided by Jupiter’s gravity and radio-energy. And the possible protection from that radio-energy and space radiation provided by the ice. Titan is intriguing for having an atmosphere that could protect putative life from space radiation.

    Robert L. Forward wrote Camelot 30K, which is about evolved intelligent life living on planetoids out in the Oort Cloud. Forward was a physicist who worked aerospace research, so his books are grounded in very hard science. It’s a pretty interesting take on alien life living in close to absolute zero (30 Kelvin).

    Liked by 2 people

    1. Europa is interesting in particular because it could harbor life somewhat similar to Earth’s, potentially.

      Life at 30 Kelvin? Interesting. It couldn’t be in methane anymore (since methane would be frozen solid at that point). It seems like all life would have to work with at that temperature would be hydrogen, helium, and maybe neon, but I’m sure Forward came up with a plausible scenario.


      1. I skimmed across the first couple chapters to see if I could spot an explanation, but didn’t find one. There are apparently compounds with extremely low boiling points that could function as “life fluids” but who’s to say fluid is necessary for life (and as you say, some gases are still liquid at those temps)? Perhaps life can be solid state.

        A couple bits I spotted while skimming: water ice at those temperatures is harder than most rocks we know. The “kerack” use it as building material, including as load-bearing beams. They cook using chemical oxidation reactions. Anything anywhere near human life temps seems to emit almost blinding light to them. It would be like us looking at molten metal.

        Liked by 1 person

        1. I would think to a Titan or 30K being, we would look like molten entities. It would be like us encountering an alien with magma for blood. On a planet that rained liquid iron (which is reality on some exoplanets), life might be very hot and fast, at least by our standards. Assuming such high temperature chemistry would allow any kind of homeostatic systems.


          1. Not just magma for blood, but for flesh! And I’m sure you’re right: high temperature life probably exists really fast!

            One of my favorite Hal Clement novels, Iceworld, is about drug runners who’ve made contact with these aliens that live on a super-cold “ice world” (too cold from them to land on — they send down landers) and can provide a drug worth lots of money.

            Guess what that “ice world” turns out to be? 😀


  2. “Personally, given the wide variety of what we call “life” here on Earth, I suspect that when we do find the first extraterrestrial life, it may well challenge our very conception of what life is. We may end up debating whether or not it actually is life, or just some kind of previously unknown complex chemical processes.”

    I can totally see this happening. Exploring something on the edge of our understanding seems to open up further possibilities, broadening our definition of life and life habitats. But then we must go back to the question of how we are defining things, and whether or not our broadening of definitions is actually useful. And of course, determining the usefulness would take time.

    Liked by 2 people

    1. I think it’s similar to what artificial intelligence will likely increasingly do to our intuitions about what intelligence and consciousness are. In both cases, we will likely encounter phenomena which is very close to our intuitions, but foreign enough to make us struggle with those intuitions.

      It also reminds me of the debate about whether Pluto is a planet. Defining planets used to be easy. First they were stars that moved around the sky, then these big spherical things that went around the sun. But we keep finding differences between things we’ve historically called planets (some are solid, some are gas) and similarities with things we’re reluctant to let in the planet club (such as spherical asteroids and Kuiper belt objects). The objects have never been anything other than what they are, but our definitions, our philosophy about them keeps changing.

      Liked by 1 person

      1. I’ll show you how an armchair philosopher gets the job done.

        Planets. I personally have my own solution. We could just have these two classifications:

        stuff that wanders
        stuff that doesn’t wander

        All set!

        Consciousness is anything I can talk to without feeling the need to look around first to see if anyone’s watching.

        Now for the hard one—that pesky botanical definition of a tomato. That obviously must go. We wouldn’t make an apple or orange sauce for our pasta, would we? 🙂


        1. Hmmm. Technically, it all wanders. You could limit it to stuff that wanders in the night sky within a human lifetime, but do you only include objects visible to the human eye? If so, Neptune and Uranus are out. If you include any wandering object that can be detected with instruments, then suddenly there are thousands of planets. Requiring that they be spherical and orbit the sun at least reduces it to 13-23 objects 😛

          So, Siri (the voice command iPhone assistant) is conscious? Or do you look around when talking with it?

          Feel free to tell me to just shut up 🙂

          Totally agree on tomatoes.


          1. LOL! I’m thinking of objects I can see in my lifetime without a bunch of expensive equipment; the rest doesn’t exist. Uranus can be out since I don’t know how to pronounce it without giggling.

            I was waiting for you to mention Siri. Siri is conscious! Think about what happens when you curse at her. She doesn’t like that, but handles it fairly well.

            (Truth be told, I don’t use Siri in public, not unless I’m having fun with it with friends. It still weirds me out.) 🙂

            YES! Gotcha on the tomatoes. Well that was my main goal, so I’m feeling like I’ve accomplished a lot today.


          2. Yes, Uranus is a difficult matter. You have to either say “your anus” or “urine-ness”, inescapably sounding like a potty mouth. Burdens.

            You curse at Siri? Poor Siri. (Of course, I’m one to talk. I turned her off.)

            Glad I could help on the tomatoes.

            Liked by 1 person

  3. Fascinating article. If I ran NASA, one of the most interesting possible forms of “life” I would want to explore would be something that uses atmospheric electricity to power itself. On a planet like Jupiter or Saturn, where there are lightning storms all the time, it seems like you could end up with some very complex and reasonably dynamic chemical systems.


  4. I’m currently researching the planet Venus and was surprised to find theoretical models for life on Venus. There’s some unknown substance in Venus’s atmosphere that absorbs ultraviolet light, and that substance could be a chlorophyll-like, sulfur based chemical. If so, there might be some kind of photosynthesizing microbes in Venus’s atmosphere.

    Every article I’ve read says this is a farfetched idea, but there does seem to be consensus that it’s at least possible. I think scientists are becoming much more open-minded to the idea that alien life might be much different than us.


    1. Hmmm, I’d be interested in reading any articles on that, if they’re on the web. (Just quickly googled around but what I found was either kooky, explained why it’s unlikely, or was about what humans would have to do to live there.)

      Given the heat, pressure, and dynamism of the Venus environment, it seems like some kind of complex chemistry could happen there, whether or not it would amount to something we’d call life.


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