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How diverse would a subterranean ocean be?

  1. Jan 5, 2016 #1
    I was thinking about Europa today and considering how life might exist on it. Spacecraft and models have shown that all of the ingredients for life is there, but I was wondering about the evolution of life after it forms. Earth had a lot of very diverse environments, which greatly accelerated evolution. It has hot water, cold water, mineral rich water, mineral lacking water, acidic areas, UV saturated areas... How many different environments would exist underneath the oceans of Europa? I'm sure that closer to the surface would be colder and less nutrient rich than the deep ocean, but how much so? Would the poles be different than the equator?
     
  2. jcsd
  3. Jan 5, 2016 #2
    Hi newjerseyrunner:

    I am not sure what you mean by the quote above re "all of the ingredients for life". Can you give a list, or at least partial list, of these ingredients? Can you give any references about "Spacecraft and models" explaining the evidence that "all the ingredients" "are there"?

    I gather from your post that you are seeking speculative answers. So I will offer you a speculation.

    I have read a few articles over the decades that present several reasons why it is plausible that Earth's moon played an important role in the transition from an organic soup to living organisms. (Unfortunately, I can't at the present time find any references to cite.) Besides the ideas in these articles, I also came up with one of my own that I am quite fond of. Since I am not an expert, it would be inappropriate for me to discuss this idea in the PF. The bottom line is, I would personally be extremely surprised if any life is ever found on Europa, except for the possibility that Earthlings might someday contaminate Europa with Earth lifeforms.

    Regards,
    Buzz
     
  4. Jan 6, 2016 #3
    For your question about the ingredients: http://www.nasa.gov/topics/solarsystem/features/europa20130404.html Galileo found that all of the precursors to organics are there.

    I'm not speculating on life there, I'm asking about the potential ecosystems of the ocean itself, that should be less speculation and more planetary astronomy / chemistry / geology.
     
  5. Jan 6, 2016 #4

    marcus

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    Good point. Diversity probably influences the complexity of what evolves as well as the rate of evolution.
    Your post got me to read a bit about the kinds of life that have evolved in Earth's deep ocean around hydrothermal vents. There are single-cell organisms that have evolved to get their energy from chemical reactions involving hydrogen sulfide and iron minerals. They don't need oxygen, or sunlight.

    Significantly, I think, there are more complex, multicell organisms that graze on these single-cell things. But as far as I could see they all require oxygen. So they rely on there being photosynthesizers somewhere else, in shallower water, using sunlight---they depend on oxygen dissolved in the surrounding water.
    This suggests to me that Earth might still not have evolved multicell life if there hadn't been sunlight and photosynthesis.
    It might still be stuck at the single-cell stage with organisms feeding on minerals and volcanic vent chemicals.

    So when you ask about diversity of environments the big diversity issue that occurs to me is the presence or absence of sunlight.

    Interesting short article on a type of tube worm that harbors bacteria in a symbiotic arrangement:
    https://en.wikipedia.org/wiki/Giant_tube_worm
     
    Last edited: Jan 6, 2016
  6. Jan 6, 2016 #5
    Hi newjerseyrunner:

    The article you cited mentioned only one compound, H2O2, as a possible source to provide energy to life forms. Here is the quote.
    A new paper led by a NASA researcher shows that hydrogen peroxide is abundant across much of the surface of Jupiter's moon Europa. The authors argue that if the peroxide on the surface of Europa mixes into the ocean below, it could be an important energy supply for simple forms of life, if life were to exist there.​
    This doesn't seem to be saying that "all of the ingredients for life is there". There was also ni mention of "models" showing ingredients for life. Were you perhaps confusing the article your cited with another article?

    Regards,
    Buzz
     
  7. Jan 6, 2016 #6

    marcus

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    Let me quote from the NASA item that NJ-runner linked to:
    "Life as we know it needs liquid water, elements like carbon, nitrogen, phosphorus and sulfur, and it needs some form of chemical or light energy to get the business of life done," said Kevin Hand, the paper's lead author, based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Europa has the liquid water and elements, and we think that compounds like peroxide might be an important part of the energy requirement. The availability of oxidants like peroxide on Earth was a critical part of the rise of complex, multicellular life."
    Again, the link to the NASA item is:
    http://www.nasa.gov/topics/solarsystem/features/europa20130404.html

    In case there's further interest we could dig up a link to the Kevin Hand et al technical paper that the news item was about.
    http://arxiv.org/abs/1303.5895
    Keck II Observations of Hemispherical Differences in H2O2 on Europa
    Kevin P. Hand, Mike E. Brown
     
    Last edited: Jan 6, 2016
  8. Jan 6, 2016 #7
    Hi marcus:

    My reading of the list of elements did not click for me that this was intended to mean "all of the ingredients for life". As I remember it (almost 20 years ago), in Chritstian de Duve's book on the origin of life "Vital Dust: Life as a Cosmic Imperative" (1996) these elements were discussed as necessary for pre-life bio-chemistry to make the organic soup from which pre-life macro-molecules, especially RNA (needed for genes) and long chain fatty-acids (needed for cell membranes) , might develop naturally, and from that environment, then the first cells might have formed.

    To call elements ingredients for life seems to me to be an overstatement. Suppose I said I planned to bake a cake, and I was asked "What ingredients do you plan to use?" Supposed I answered, "Water, carbon, nitrogen, phosphorus, and sulfur." Do you think that would be a reasonable answer?

    Regards,
    Buzz
     
    Last edited: Jan 6, 2016
  9. Jan 6, 2016 #8

    marcus

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    I don't see the point of this talk about talk. Kevin was speaking informally and didn't go into pedantic detail as to the key compounds.
    http://www.space.com/26905-jupiter-moon-europa-alien-life.html
    ==quote Space.com==
    But beneath its icy crust lies a liquid ocean with more water than Earth contains. This ocean is shielded from harmful radiation, making Europa one of the solar system's best bets to host alien life.

    That's one of the reasons Europa is so alluring to scientists. It has all the elements thought to be key for the origin of life: water, energy, and organic chemicals, the carbon-containing building blocks of life, scientists said at an event icon1.png called "The Lure of Europa," held here last month. [Europa and Its Underground Ocean (Video)]
    ==endquote==
    "elements thought to be key" for life, here, does not mean periodic table chemical elements, it means organic chemicals and various other things.
     
    Last edited: Jan 6, 2016
  10. Jan 7, 2016 #9
    The conditions on Europa are interesting in that the key elements for life are there.
    However we still remain clueless (only some reasonable guesswork) regarding how a similar organic soup on early Earth kicked of into the cyclic self replicating stuff that became life on Earth.
    Life on Earth requires nucleic acids which produce proteins, but to make nucleic acids requires proteins.
    A bit of a conundrum that.
     
  11. Jan 7, 2016 #10

    Chronos

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    An ocean could have many environments, assuming vulcanism. There could be anything from steaming mineral springs to icy sludge pits I think the former is a more promising place to look for abiogenesis. Although an alternating cycle might be the best conditions. A vent that peridiodically cooks up the sludge might be the ticket.
     
    Last edited: Jan 7, 2016
  12. Jan 7, 2016 #11
    Hi @marcus and @rootone:

    I apologize if my posts came across as my being apposed to further exploration of Europa. I think further exploration is quite justified. My complaint is in the language used to describe the contents of the article cited by newjerseyrunner. It came across to me me as being hyped.

    Also, marcus, your post #8 seems to be saying that the article said that "organic chemicals" were mentioned in the article as being found on Europa. I searched the article for "organic" and failed to find this word there except in one place:
    This artist's concept shows a possible explosion resulting from a high-speed collision between a space rock and Jupiter's moon Europa. Clay-type minerals have been found on Europa's surface in a new analysis of data from NASA's Galileo mission. The pattern of these minerals suggests an asteroid about 3,600 feet (1,100 meters) across or a comet about 5,600 feet (1,700 meters) across could have hit at a shallow angle. Clay-type minerals are commonly found in primitive asteroids and some comets. These kinds of asteroids and comets also typically carry organic compounds, providing a possible way for organics to be delivered to Europa.​
    I interpret this to be a speculation of the plausibility that organic compounds might possibly exist on Europa. I do not interpret it as the article saying that
    That is, that all the essential ingredients (including organic compounds) for life have been found on Europa.

    Regards,
    Buzz
     
    Last edited: Jan 7, 2016
  13. Jan 7, 2016 #12
    Hi @rootone:

    The de Duve book I cited, as best as I can remember it, makes a very strong case that RNA preceded proteins. RNA has a very flexible backbone, unlike DNA, and long chain RNA can form 3D shapes that can act like enzymes. Also, I recollect that after the Miller-Urey experiment (1952), similar experiments by others also produced nucleic acids. The organic soup that preceded RNA included nucleic acids.

    Regards,
    Buzz
     
  14. Jan 7, 2016 #13
    Hi @Chronos:

    I am very curious about why you propose an "alternating cycle". My own pet idea about the role of the Earth's moon involves a four phase alternating tydal cycle which the sun and the moon provides.

    Regards,
    Buzz
     
  15. Jan 7, 2016 #14
    Probably a cycle of large amounts of chemicals being pumped into the water by volcanic vents, then periods of time where the vents were inactive. That makes sense, when there is lots of chemicals to eat, life will flourish, and diversify, natural selection would favor organisms that could breed quicker. During the vent's downtime, evolution would favor organisms that are most energy efficient and tougher.
     
  16. Jan 7, 2016 #15
    Hi newjerseyrunner:

    Thanks for posting a response to my question. It seems like a useful concept for how a lot of variation might arise.

    Regards,
    Buzz
     
  17. Jan 10, 2016 #16

    Chronos

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    Buzz, I agree tidal effects could be an important variable, but, all politics is local and local variation could be an even more significant contributor.
     
  18. Jan 10, 2016 #17
    Hi @Chronos:

    I agree local variation is much more significant once the first lifeforms exist. The tidal idea relates to the "evolution" from organic soup via the "RNA World" (as described by de Duve) to the first cell.

    Regards,
    Buzz
     
  19. Jan 20, 2016 #18
    Buzz said: "I have read a few articles over the decades that present several reasons why it is plausible that Earth's moon played an important role in the transition from an organic soup to living organisms."

    Here is a link to a little article on the role the moon may have played here on earth in the exolution of life: http://www.scientificamerican.com/article/moon-life-tides/
     
  20. Feb 12, 2016 #19
    Hi @Dan DePerez:

    Thanks for the link.

    I notice that the article gives a value of 12 hours for the rotation of the earth at the time following the creation of the moon. Do you know any reference that gives a value for the moon's distance and orbital period at that time, and whether of not the mass of the Earth and/or Moon have significantly changed since then.

    Regards,
    Buzz
     
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