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Could a Titan probe detect life with polarized light?

  1. Jun 29, 2015 #1
    I had a thought and was wondering if it's viable to detecting whether or not life exists in Titan's hydrocarbon seas, whether we get direct evidence or not.

    Titan lakes are hydrocarbons, which likes to create twisted polymer chains. Nature (lightning, cosmic rays...) should produce polymers that twist to the left and to the right in equal quantities. If we take a sample of a Titan lake could we shine polarized light through it to detect the concentration of twisted polymers in both the right and left directions?

    If only natural processes exist on Titan, the concentrations should be more or less equal, however, if evolutionary processes exist, life-form will only produce the polymer in the same handedness as it's parent, ergo there should be a subset of polymers that exist in one direction in significantly higher quantities than the other.
    Last edited by a moderator: Jun 29, 2015
  2. jcsd
  3. Jun 29, 2015 #2


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    I'm not sure that optical activity would be a good indicator of the presence of life. Many in the origin of life field have hypothesized that an enantiomeric excess of certain sugars and amino acids preceded the life and lead to the homochirality of life, not the other way around. Although no one has found any definitive answers yet, a variety of mechanisms have been proposed for the non-biological origin of such an enantiomeric excess through purely chemical or physical means. For a review, see for example Blackmond 2011. Phil Trans R Soc B. 366:2878. doi:10.1098/rstb.2011.0130.
  4. Jun 30, 2015 #3
    Interesting, thanks.
  5. Jun 30, 2015 #4


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    Although that would still be quite an encouraging find. If not life, we'd still have found a/the positive feedback loop that is the precursor to life.
  6. Jun 30, 2015 #5


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    Absolutely. Discovering chiral molecules there and understanding how they got there would be a huge leap forward for the origin of life field. The experiment (if feasible) is certainly worth doing. I'd just argue against interpreting a positive result as definitive evidence for life on Titan.
  7. Jun 30, 2015 #6
    Oh, thats an interesting tangent i never thought of
  8. Jun 30, 2015 #7


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    I think that due to the "autocatalytic" nature of life any small excess of one form soon becomes a 100:0 ratio, so I think it is a good indicator. I think whenever possible extra planetary missions and observations will look for chiral molecules.
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