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Implications of life being found or not found on Europa

  1. Apr 7, 2016 #1
    Wikipedia
    says that
    "Scientists' consensus is that a layer of liquid water exists beneath Europa's surface, and that heat from tidal flexing allows the subsurface ocean to remain liquid."​
    There have been speculations that Europa might contain life. For example,
    "Europa is the most likely place in our solar system beyond Earth to possess .... life," said Robert Pappalardo, a planetary scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.
    http://phys.org/news/2013-02-jupiter-europa-moon-likeliest-life.html
    I am curious to find out what the knowledgeable participants at PF speculate the implications are if, someday, life is found on Europa, or Europa is found to not have life. In particular how will such a finding affect the likelihood that life exists on some exoplanet in the Milky Way. That is, to what extent would finding (not finding) life on Europa affect the probability that life exists (does not exist) elsewhere in the Milky Way.

    Another area of interesting speculation would be: If life is not found on Europa, what particular difference(s) between Earth and Europa might explain this. For one example, it might be that liquid water temperatures on Earth range from < 0 C (due to salts in the ocean) to 100 C (due to sub-ocean mantle plumes), while the range of water temperatures on Europa are likely to be more limited.
     
  2. jcsd
  3. Apr 7, 2016 #2

    phinds

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    Not finding life on Europa would be just boring and of no particular consequence, but FINDING it, or finding life anywhere other than Earth, would be a big deal indeed.
     
  4. Apr 7, 2016 #3

    Ygggdrasil

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    An interesting question if life exists on Europa would whether it seems to share a common ancestor with life on Earth. Common ancestry could provide support for theories of panspermia, whereas an independent origin of life would suggest that abiogenesis is fairly common and we should expect to find life in similar environments across the universe..
     
  5. Apr 7, 2016 #4
    Would it matter if it were single cell or multi-cell?
     
  6. Apr 7, 2016 #5

    Ygggdrasil

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    Nope. I would suspect the common ancestor, if one were to exist for these hypothetical lifeforms, would have been a single-celled organism (probably similar to the LUCA on Earth).
     
  7. Apr 7, 2016 #6
    Hi phinds:

    I confess I am surprised by this answer. I would think that it would constitute, among other things, very strong evidence that just having water on a planet/moon is not sufficient for life to evolve there.

    Regards,
    Buzz
     
  8. Apr 7, 2016 #7
    Hi Greg:

    Yes, I think this would matter with respect to the likelihood that multi-cell life exists on exoplanets in the Milky Way. It would also matter a lot if the Europa multi-cell life were not like Earth's Eukayotes, but consisted of instead of bacteria-like or Archaean-like cells.

    Regards,
    Buzz
     
  9. Apr 7, 2016 #8

    phinds

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    Absence of evidence in a particular case is not evidence of absence in general.
     
  10. Apr 7, 2016 #9
    :smile: I would just want to make the thread more colorful...
    Is that still a young planet ? I agree with phinds about this that it doesn't really matter if life isn't found on Europa since our discovery of new lifeforms outside the earth, no matter where it will be, I think would be more important.
    Very likely, because it helps us confirm our theories on what basic materials these lifeforms need to evolve from right on Europa and further make other assumptions about life possible in other planets if the same conditions are met.
    How would it matter then ? I think it is how the first cells are born, though.
    And it is true that some lifeforms can survive and evolve without water as their prerequisite.
    :biggrin: very true.
     
  11. Apr 7, 2016 #10
    Hi Pepper Mint:

    You asked
    "How would it matter then?"​
    regarding what I said
    "It would also matter a lot if the Europa multi-cell life were not like Earth's Eukayotes, but consisted of instead of bacteria-like or Archaean-like cells."​
    I have recently been reading (and enjoying) The Vital Question by NIck Lane (2015), in which a well reasoned argument is given about why bacteria and Archaea failed to evolve into multi-cellular creatures.

    You ares said:
    What is your basis for claiming this is true?

    Regards,
    Buzz
     
  12. Apr 7, 2016 #11

    Ygggdrasil

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    It is worth noting that not all agree with Lane and other who make such arguments. Here is a nice paper arguing that, as eukaryotes ourselves, we tend to hold a eukaryo-centric view of evolution: http://www.pnas.org/content/112/33/10278.abstract

    That said, as eukaryotes comprise all complex life and there are no known examples of complex prokaryotic life, there may be something to the arguments of Lane and others.
     
  13. Apr 7, 2016 #12
    Both would have huge implications.

    Not finding it means that there is some filter for life that we haven't figured out yet, it'll also provide information about the Drake equation by showing us that even simple life is rare. Europa's oceans seem perfect, if there isn't life there, we're not understanding something.

    If there is life there, I'd be very interested to take it's genome and find out if we're related. It'd be strong evidence that earth life may not have started on Earth. We might be able to calculate backwards and figure out how long ago our common ancestor likely lived. If that number is older than the solar system, well then that means that life is probably extremely common since it can spread between stars easier than we think it can now. Right now it's assumed that nothing could survive an interstellar journey, not even the toughest microbes. If that number is about the same age as the solar system, that means life can migrate between planets, but provide little to no information about beyond that.
     
  14. Apr 7, 2016 #13
    Other than that a subsurface ocean seems likely to exist beneath a thick ice crust, I don't think we know much more about it at this stage.
     
  15. Apr 7, 2016 #14

    phinds

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    What do you base that on? Just because there are good conditions for life doesn't mean that has to BE life.
     
  16. Apr 7, 2016 #15

    ProfuselyQuarky

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    I have so many things to say about this . . . :(
     
  17. Apr 7, 2016 #16

    jim mcnamara

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    @phinds is saying 'you cannot logically disprove a hypothesis with a single experiment/exploration because you would need to enumerate all cases'. < good!
    You establish a better explanation/hypothesis and test that instead. Since everyone is making assumptions here is one: we may make tests for life that the 'lifeforms' in Europa's oceans fail. This is an example of why failure is not the endpoint. This somewhat absurd example is also why our 'Eukaro-centric' worldview could get us a false negative as well.
     
  18. Apr 8, 2016 #17
    No, but we tend to make that assumption based on the single data point that life on Earth started essentially as early as it could. It's (circumstantial) evidence that if the conditions are right, life will just go. If the oceans down there seem perfect, but there is nothing there, we'll have to rethink how easy it is, and therefore wonder why it happened so quickly on Earth. It'd also bring new life to the Rare Earth idea, which has fallen out of favor in the recent flood of exoplanets.
     
  19. Apr 8, 2016 #18

    phinds

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    I understand what you're saying but I think you're giving too much weight to a single data point.
     
  20. Apr 8, 2016 #19
    With regard to the likelihood of finding life in the Solar System, if Earth is #1 and Europa is #2, what planets/moons would be #3, #4, and #5?
     
  21. Apr 8, 2016 #20
    Ganymede, Enceladus, and Mars are all candidates for life as we know it and Titan has the potential for more exotic life.
     
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