Forgot your password?
typodupeerror
Space

Using Light's Handedness To Find Alien Life 210

Posted by timothy
from the let's-skip-some-steps-in-the-middle dept.
Rational Egoist writes "Scientists working at the National Institute of Standards and Technology have come up with a novel, easy way to detect life on other planets. Rather than try to measure the composition of atmospheres, they want to look at the chirality of light coming from the planet. From the article: '"If the [planet's] surface had just a collection of random chiral molecules, half would go left, half right," Germer says. "But life's self-assembly means they all would go one way. It's hard to imagine a planet's surface exhibiting handedness without the presence of self assembly, which is an essential component of life."' And they have already built a working model: 'Because chiral molecules reflect light in a way that indicates their handedness, the research team built a device to shine light on plant leaves and bacteria, and then detect the polarized reflections from the organisms' chlorophyll from a short distance away. The device detected chirality from both sources.' The article abstract is available online."
This discussion has been archived. No new comments can be posted.

Using Light's Handedness To Find Alien Life

Comments Filter:
  • One problem (Score:5, Funny)

    by eclectro (227083) on Friday April 24, 2009 @01:21AM (#27698357)

    What if the aliens are ambidextrous?

    • Re:One problem (Score:4, Informative)

      by Hal_Porter (817932) on Friday April 24, 2009 @02:45AM (#27698775)

      Then this scan won't find them and no preemptive Relativistic Kill Vehicle [wikipedia.org] will be dispatched to their planet.

  • by Kral_Blbec (1201285) on Friday April 24, 2009 @01:22AM (#27698363)

    if you had to google chirality

  • by nz17 (601809) on Friday April 24, 2009 @01:42AM (#27698465) Homepage

    CBC's science program Quirks and Quarks had an interesting story about the handedness of molecules [www.cbc.ca] that it played last month. (Audio available in Ogg Vorbis) It provides a nice, friendly introduction to this topic.

  • This sound very interesting. Maybe there are business opportunities with Aliens. What do you think they would be ready to buy from us? Maybe something to show an even distrubution of chiral molecules could avoid their friends on other planets to also get discovered by nasty sellers from Earth, but I am not sure we should sell such a thing. Any valid business idea?
    • Youd make a killing on Left-handed scissors and golf clubs

      http://www.anythingleft-handed.co.uk/golf.html [anythingle...nded.co.uk]
    • by Dunbal (464142)

      This sound very interesting. Maybe there are business opportunities with Aliens. What do you think they would be ready to buy from us?

      Knowing us humans, we will probably be able to supply what they crave most: PORN. The interstellar DVD trade will flourish, with constant streaming of jellyfish polyps budding off, jellyfish polyps turning into medusae and for those real sickos, jellyfish catching and eating fish.

      Hey I don't ask questions, I just sell it.

  • by Merakis (959028) on Friday April 24, 2009 @01:43AM (#27698479)
    So, to sum up the article... Chirality is not dead!
  • by Anonymous Coward

    One more trek concept brought to real-life, yay! (The other one being the communicators on TOS)

    - AC, patiently waiting for warp drives

  • Wow (Score:5, Insightful)

    by ShooterNeo (555040) on Friday April 24, 2009 @01:47AM (#27698501)
    This just might work. It'll take incredibly good optics, of course, and the chirality of the light from these distant planets might be lost when the light goes through the earth's atmosphere. Might take a gigantic telescope in outer space.
    • If only we had one of those..
    • by rts008 (812749)

      Might take a gigantic telescope in outer space.

      What would be really cool would be able to build one of those array type telescopes(really, outrageously Humongus sized) at one of the lagrange points.

      • Re: (Score:2, Funny)

        by sFurbo (1361249)

        (really, outrageously Humongus sized) at one of the lagrange points.

        No, please don't give them any more stupid ideas for what to call large telescopes [wikipedia.org]

        • Re: (Score:3, Funny)

          by Theaetetus (590071)

          (really, outrageously Humongus sized) at one of the lagrange points.

          No, please don't give them any more stupid ideas for what to call large telescopes [wikipedia.org]

          Let's see...

          Freakish Array of Radio Telescopes?
          Stupidly Large Ultraviolet Telescope?
          Binary Interferometric Narrowband Telescope?
          Coordinated Unit of Networked Telescopes?

    • This just might work. It'll take incredibly good optics, of course, and the chirality of the light from these distant planets might be lost when the light goes through the earth's atmosphere.

      Then it'd also be lost going through the source planet's atmosphere.

      I don't see the scheme working.

  • I'm sceptical.... (Score:5, Interesting)

    by Genda (560240) <marietNO@SPAMgot.net> on Friday April 24, 2009 @01:57AM (#27698551) Journal

    The whole reason that life produced molecules of fixed chirality is that molecules precursing life are generated in cold gase nebulae that are often effected by radiation from young stars which have a particular chirality. That is to say, the cold nebulae that was the precursor of the Sol system, had light whose chirality precipitated right handed sugars and left handed amino acids.

    A planet let's say, made of hydrocarbons and complex organic molecules that formed in such a cold dark nebulae, might have no life, but it's chemistry would in fact have fixed chirality. That is to say, someone needs to point the first instance of this instrument at Titan, a place where we are pretty sure no surface life (as we know it) might exist, but whose surface chemistry may very well have preserve some of the chirality of the nebulae that formed the Sol system. If we receive significant chirality frozen in the Titan surface, it would be a strong indicator that this test is less than optimal for finding earth like planets.

    • If Titan has mixed chirality, would this reduce the efficiency of agriculture on that planet? I am thinking that we might try to use indigenous molecules to grow food. If the mix was 50% presumably only half the molecules would work for us.
      • by MaskedSlacker (911878) on Friday April 24, 2009 @03:39AM (#27698959)

        Not all molecules are chiral. Simple molecules which form the raw materials for life forms are not themselves chiral because they are symmetrical (O2, H20, NH3, CO2, etc; chirality is only possible for asymmetric forms molecules). The simplest solution the problem you describe is to introduce simpler lifeforms from earth--bacteria or archaea to start producing organic molecules of the correct chirality from the raw material precursors.

    • by Sibko (1036168)
      Or it might tell us that there's life on the surface of Titan...
      • by Dunbal (464142)

        Or it might tell us that there's life on the surface of Titan...

              Certainly not life as we know it. I can just imagine what would happen to all those algae once they manage to produce enough oxygen to - well let's say that's one world with the potential to eventually "go out with a bang". Hopefully for them any life there would use a different oxidizer...

    • Re:I'm skeptical.... (Score:5, Informative)

      by Richard.Tao (1150683) on Friday April 24, 2009 @03:46AM (#27698995)
      You appear to be wrong on a few big things...
      -most compounds are not chiral, so even if a dead planet had some pure enantiomers, they would be insignificant compared to one with life, life produces a crazy large amount of them
      -no one has quite figured out why life has the handedness it does, some say it could be because of silicon catalyzing a certain handedness, others disagree, there is not an answer to this question yet, but it makes sense that life would evolve to have a specific handedness so all the parts could be interchangeable and we don't have bizzaro ecoli floating around that can exchange DNA with normal ecoli
      -since when does polarized light catalyze chiral reactions?? UV light can catalyze reactions, and chiral molecules can cause a reaction to form with a specific handedness, but only chiral MOLECULES can catalyze reactions to cause a more enantiomericly pure product
      • Re: (Score:3, Informative)

        by sFurbo (1361249)

        -since when does polarized light catalyze chiral reactions?? UV light can catalyze reactions, and chiral molecules can cause a reaction to form with a specific handedness, but only chiral MOLECULES can catalyze reactions to cause a more enantiomericly pure product

        Not quite, IIRC, there are examples of some reactions with polarized light which gives ~1% excess of one enantiomer. It has been hypothesized to be the origin of the handedness of life. But in itself, it will not give enough of a excess to be meassured with this technique.

      • Re: (Score:3, Interesting)

        by TeknoHog (164938)

        -no one has quite figured out why life has the handedness it does

        I recall a theory that it is due to the slight asymmetry in weak interaction, but I've forgotten the exact mechanism. This asymmetry exists basically everywhere in the universe, but as life is self-replicating, it can amplify the effect to a great extent. Here's the first reference found via quick googling:

        http://www.springerlink.com/content/0743577n4716u23j/ [springerlink.com]

      • I recall a story about it, someone in this thread linked to a Quirks and Quarks story where it turned out that comets have been shown to have a tendency to lean towards containing amino acids with a certain handedness. The thought is that life likely formed with that handedness because there were more amino acids to work from.

      • Re: (Score:3, Interesting)

        by Cyberax (705495)

        Also, don't forget racemization (http://en.wikipedia.org/wiki/Racemization) - a lot of enantiomeric compounds can spontaneously switch chirality (it's actually a big problem for some extremophile bacteria - they replicate so slowly because they have to expend energy to repair damage from racemization).

    • Re: (Score:2, Informative)

      by endall (148631)

      According to this article ( http://asunews.asu.edu/20080229_pizzarello [asu.edu]), an un-contaminated meteorite was was found to have amino acids with mixed chirality, but with a bias towards the left-handed (up to 15%), not the 50%-50% suggested in the article linked in the submission. So to some extent, this supports what you said.

      Even so, the technique described in the submitted article could work. It's all about signal to noise. If some feature of a planet reflects vastly more chiral bias than a rocky moon or aste

  • by Omnifarious (11933) <eric-slash&omnifarious,org> on Friday April 24, 2009 @02:00AM (#27698559) Homepage Journal

    First, for those who are wondering "What the heck is chirality?". So, you have left handed gloves and right handed gloves, and you can't transform one into the other without doing something like flipping it through a fourth spatial dimension (strangely, flipping it through the time dimension will result in an opposite handed glove traveling backwards in time that's made of antimatter) or turning it inside out. Proteins, also being three dimensional objects, are the same way. And there is a convention for deciding whether a given molecule is right or left handed. Chemical processes tend to produce equal numbers of left and right handed versions. Biological processes on earth tend to produce almost exclusively right handed molecules.

    I didn't know this before reading the article, but it makes sense... the chirality of a molecule apparently affects the polarity of the light that is reflected from it or transmitted through it.

    Now, to talk about what I think of the article...

    Scientists make too many assumptions. Life requires self-replication... that's it. It doesn't require water and it doesn't require chirality. It doesn't require a whole host of things that scientists tend to assume it requires simply because it's a characteristic we've observed about life on earth.

    But, I will agree that if they can detect the predominance of one particular chirality then that's a strong indicator of some life-like process at work.

    That absence of chirality is no indicator that there isn't life. It just won't resemble the life we have here on earth.

    It may be possible to prove that self-replication within a given system (like chemistry, for example) is very hard without certain conditions. I'm willing to believe, for example, that non-carbon based life that primarily functions chemically is highly unlikely because carbon is such a fantastically versatile atom chemically speaking.

    Of course, there might be life based on nuclear processes [wikipedia.org] or, even farther fetched, life based on gravitational processes. As support for the second, galaxies have a very complex lifecycle in which supernovas and black holes play key roles. They eat the thin gas left over from the big bang, and metabolize it into new stars with supernovas and black holes. I'm not sure where self-replication fits into that picture so galaxies may just be metabolism absent a mechanism for self-replication (i.e. engines) and hence not really alive.

    Life based on nuclear processes or gravity is certainly not going to exhibit any chirality signature, nor require water or even carbon.

    But, as I said, I will agree that a chirality signature is strong evidence for chemistry based life. I just don't think its absence is strong evidence against life.

    • Further research shows that I'm wrong about the chirality of life on earth. Apparently left and right handed aren't used as such in biology. Amino acids, and hence proteins have L- chirality and sugars have D- chirality [wikipedia.org].

    • by RsG (809189)

      I'll avoid the obvious pitfall of pointing out that we can't conclusively prove a negative. I think that, at any arbitrary point in the future, we'll either have found non-carbon life, or we'll still be arguing over it's existence. Science fiction of the thirtieth century should be an interesting read :-)

      However, we need to look for the carbon-based life first, regardless. We currently have a sample size of one for livable planets, and that tells us next to nothing about the rest of the universe. Is our

    • Arthur C Clarke wrote a great story about this.

      Spoiler Alert

      An engineer gets exposed to an intense magnetic field during an accident in a power station. While recovering from his injuries it turns out that he can no longer extract energy from normal human food. The theory is that the field created a volume of four dimensional space within which he rotated before the power was removed. Faced with the prospect of starving to death he agrees to repeat the exposure in the hope that he will get rotated arou
    • "Scientists make too many assumptions."

      I disagree, enumerating and testing assumptions is at the core of their job description. They don't have any examples of "life as we don't know it" so they cannot make ANY TESTABLE ASSUMPTIONS about it, if scientists cannot test it then it's NOT science. This probably explains why your dragon's egg link is classified as fiction.

      Life requires self-replication... that's it. It doesn't require water and it doesn't require chirality. It doesn't require a whole host o
      • Crystals self replicate on the atomic scale so I think your definition requires some work.

        This is true. I believe there is a more formal definition out there involving the ability to evolve [wikipedia.org]. But defining exactly what that means can be a bit tricky.

        I disagree, enumerating and testing assumptions is at the core of their job description. They don't have any examples of "life as we don't know it" so they cannot make ANY TESTABLE ASSUMPTIONS about it, if scientists cannot test it then it's NOT science. This probably explains why your dragon's egg link is classified as fiction.

        ...

        It's a shame you felt you had to take a poke at scientists since you are obviously an intelligent life form and the rest of your post contains some interesting speculation.

        I disagree. For example, I think looking for chirality is a much more general, and a stronger test than looking for water. I think what you want to look for is evidence of complex self-ordered systems.

        I do agree that looking for life that's like the life we already have first hand examples of is the easiest thing to do, and probably what we should

        • I think you're arguing mostly about language. A scientist, speaking scientifically, uses constrained definitions of words. "Life" in the scientific sense is only what we know on Earth, since science requires evidence and all our evidence of life is here on Earth. And everything we know to be alive on Earth does in fact require water. Thus it is a scientifically supportable statement to say that "life requires water."

          That does not make it true...science is not so much concerned with "truth," but with what it

    • Re: (Score:3, Funny)

      by 4D6963 (933028)

      So, you have left handed gloves and right handed gloves, and you can't transform one into the other without doing something like flipping it through a fourth spatial dimension

      Little known fact : that's actually how right hand gloves are made. Turns out that using a fourth spatial dimension is cheaper than machinery to build both types of gloves.

      • by Dunbal (464142)

        Little known fact : that's actually how right hand gloves are made. Turns out that using a fourth spatial dimension is cheaper than machinery to build both types of gloves.

              That "fourth spatial dimension" actually being kids in sweatshops in China and Malaysia?

  • by cyn1c77 (928549) on Friday April 24, 2009 @02:07AM (#27698605)

    If we can't actually go visit any aliens we detect because they are light years away, it is just going to drive us batty.

    And I don't really want the aliens coming to visit us either, because that would mean they were more technologically advanced than humans. And the inferior species always seems to end up as food or raw material. Come on, even Hollywood has figured this out!

    • But if we detect they're right handed, we can at least be sure they won't eat us (or rather, won't get any nutritional value from eating us :-)

  • by dido (9125) <dido@NOsPAm.imperium.ph> on Friday April 24, 2009 @02:13AM (#27698631)

    I suppose that if you were to detect chirality bias in the light coming from a particular planet, that would probably be sufficient to conclude that there might be some form of life on that planet that was causing that particular bias. However, it doesn't seem that it's a necessary condition, i.e. not detecting chiral bias might mean that there might after all be some very strange life form on the planet whose chemistry made use of both left and right handed molecules. In fact, there are some strange life forms on Earth, notably archaea [wikipedia.org], that actually use right-handed proteins in some aspects of their biochemistry, quite unlike all other life forms found on earth, which use left-handed proteins exclusively.

  • Test it on Europa (Score:3, Insightful)

    by kn0tw0rk (773805) on Friday April 24, 2009 @02:28AM (#27698711) Journal

    Surely this would be a good test to check out Europa?

    Even though the ice crust might obfuscate things, if the light was from reflected from the area of a crevice/crack then there would be elements (or the lack thereof) in the frozen water that give some indication.

    • by jschen (1249578)

      Test it on earth first! Lots of chiral molecules on earth rotate light in one direction. Lots rotate it the other way. So the total rotation is going to be rather small. Furthermore, most molecules (including all of the atmospheric gases) are not chiral. The scientists should start by trying to detect life that's one meter away by measuring optical rotation. I doubt they'll manage. But if they do, then they can move on to longer distances.

      For what it's worth, though, the scientists appear to be well aware o

  • Based on the little-known work of Dr. Peter Pullet-Wildly, it should be possible to detect not just alien life, but alien intelligence. Because if you encounter left-handed rather than right-handed chirality, it feels like somebody else.

    Unless you're a southpaw, of course.

  • By using a combination of rice paper and domestic household bleach you can detect if a planet is either Regular or Goofy footed...

  • I like the idea. It looks like an execellent tool to add to the toolbox for determining the probability of an extrasolar planet harboring an ecosystem.

    Of course, an alien ecosystem could have evolved to use both handednesses, but the information that one handedness is predominant on the planet is a strong hint that there's something unusal going on there. Same goes for the detection of unusually large quantities of unstable substances (oxygen, halogens, etc) in the atmosphere of the planet.

  • Using Light's Handedness To Find Alien Life

    Because the heavy handed approach we've taken so far is not working?

    Oh wait...

  • That is a very weak cup of tea. For one thing, I can't see what is new in this; we have been able to do this sort of thing for decades. Also, I don't think we would be able to detect life on Earth using this method, let alone another planet lightyears away. The biomass on Earth is actually rather minute compared to the whole of the atmosphere or the oceans, so the signals would be weak, even for our own planet; and there are many things between us and our neighboring stars that could both polarise and depol

  • by exp(pi*sqrt(163)) (613870) on Friday April 24, 2009 @04:51AM (#27699251) Journal

    ...is that life forms a kind of amplification process.

    If you have some random soup of molecules formed by abiotic processes then apart from some small biases brought about by parity-violating fundamental physics we expect complete symmetry between left- and right-handed molecules.

    But life, arguably, forms a kind of amplification process. Competition between molecules with different chirality might serve to increase any initial small difference between one group and another. So what starts as almost exact symmetry results in a planetwide bias one way or the other.

    But there are two issues.

    (1) Could such a planetwide bias show up strongly enough in the polarisation of light reflected from the planet. It seems very unlikely given how messy a planet is. Let's say you pick a million different types of molecule than come in chiral pairs and for each molecule pick one of the pair, discarding the other. Now jumble up many different copies of each of these molecule types. Your chances of detecting chirality from afar is minimal even though, in some sense, the mixture is perfectly chiral, because of the overall randomness of the mixture.

    (2) Could any other physical processes cause such amplification? The answer is yes. For example some kinds of crystal growth can result in homochirality.

    So I'm pretty sceptical despite the idea being neat.

  • Material from space has already been shown to exhibit chirality. There's quite a nice review on...

    http://scienceandreason.blogspot.com/2009/04/amino-acid-chirality.html [blogspot.com]

    We do not know that this chirality comes from life. People have presented this as evidence that life exists in space, that life was seeded from space, and all sorts of other stuff. All we actually seem to know is that some stuff out there shows a handedness. If your light is passing through chiral material in space it will pick up a pola

  • by Herve5 (879674) on Friday April 24, 2009 @08:59AM (#27700509)

    I requested the full paper but... as we are friday afternoon here in Europe I'll probably get it on Monday ;-)
    In the meanwhile, from the abstract I feel this'll be more applicable to say checking remotely life hints in Jupiter's atmosphere here, than getting answers for remote stars tomorrow.

    I for one highly doubt, for instance, that just analysing an exoplanet's transit onto its star will bring any measurable polarization.
    Just remember what you see is star light that passed through the planet's *atmosphere*, not reflected onto its ground (and grass/trees).
    And as this specific light is moreover buried within the 99,99% of starlight that just didn't cross the planet at all, even with a specifically intense *atmospheric* life (a dense, GREEN atmosphere ;-) it'll be very difficult to detect the ppm of added polarization.

    Rather, I see this either for

    a) a futuristic payload for the (too futuristic) Darwin project from Esa/Nasa ( http://www.esa.int/esaSC/120382_index_0_m.html/ [esa.int] ), when the dozen of years of development (and equal number of euro and dollar billions) will have been invested: if things go well, no more crises, etc., we then will have a way to just switch the starlight off (via destructive interferometry), and see only planet's light.
    Then maybe you'll measure polarization. But then you'll also measure specific wavelength absorptions, so get directly to molecules (which is the raison d'être of the Darwin project)

    b) as said earlier, maybe in nearer times a way to observe our neighboring planets atmospheres, and suddenly discover they may be polarized (or not, and that check will be quick).
    If they were it'd definitely be fun.

    In my space factory there is a breadboard of the Darwin nulling interferometric concept. Nifty. Representing maybe 1% of the required development work. But nifty, definitely: capable of switchig off a star light that is millions of times superior to the planet's reflected light and at the same time leave planet's light in, when planet is just the pixel against the star's one. As they say on Esa's site, capable of seeing a candle light stuck against a lighthouse firewindow, from 1000 km away.

  • If we discover life that is of opposite handedness to the life on this planet, then they wouldn't be able to eat us.
    On the other hand we wouldn't be able to eat them :(
    but on the gripping hand thry could still hunt us for sport. (or we could hunt them for sport.)

  • If this method for detecting life works well then you better believe any advanced alien civilization relatively close to us probably already knows exactly where we are. Perhaps we should hope that life is so common in the universe that they are working their way down a long boring list of warm wet rocks with weird crap growing on them and it will take them a long time to investigate us.
  • "If the [planet's] surface had just a collection of random chiral molecules, half would go left, half right," Germer says. "But life's self-assembly means they all would go one way. It's hard to imagine a planet's surface exhibiting handedness without the presence of self assembly."

    He's not talking about life, he's talking about Earth life. We have only one data point to go by, which is too little to draw generalities from.

    It is perfectly plausible that a biosphere could be bichiral. There could be parallel

  • The planet Zorran, neighbor of Tattoonie, has an interesting biology. The left handed chirals evolved into the plants and the right handed Zorrans evolved into animals. How do the animals digest the plant matter you ask? Well their mitochondria is actually ambi-chiral called mitachloreans. Thus the light reflected by Zorrans has both left and right handed chiral-photons.
  • I agree that chirality implies some kind of autocatalytic process to amplify weak natural chiral bias or statistical fluctuations, but I don't agree that it is diagnostic for life. After all, crystals self-assemble, so a planet dominated by large crystal structures could be highly chiral.

    Self-assembly is only part of the definition of life--there also needs to be mutation, and the mutation has to affect the propagation of subsequent generations.

It's time to boot, do your boot ROMs know where your disk controllers are?

Working...