Life 'not as we know it'?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by paddoboy, Mar 2, 2015.

  1. paddoboy Valued Senior Member

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    Life 'not as we know it' possible on Saturn's moon Titan
    by Staff Writers
    Ithaca NY (SPX) Mar 02, 2015


    A new type of methane-based, oxygen-free life form that can metabolize and reproduce similar to life on Earth has been modeled by a team of Cornell University researchers.

    Taking a simultaneously imaginative and rigidly scientific view, chemical engineers and astronomers offer a template for life that could thrive in a harsh, cold world - specifically Titan, the giant moon of Saturn. A planetary body awash with seas not of water, but of liquid methane, Titan could harbor methane-based, oxygen-free cells.

    http://www.spacedaily.com/reports/Life_not_as_we_know_it_possible_on_Saturns_moon_Titan_999.html
     
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  3. Yazata Valued Senior Member

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    Methane-based lifeforms on cold planets were a staple of 60's-style science fiction.

    One thing that's always put me off the search for life on other planets is the assumption that exobiology must be the duplication of Earth-life elsewhere. I always suspected (old sci-fi reader that I am) that if life appeared someplace else, it might be very different biochemically from what we expect. It just seems to me that a lot about Earth-life is fortuitous, the product of its origin, its long history and all of the selective pressures that it's been subject to.

    If life were to independently appear somewhere alien, if the chemical details of its initial appearence were significantly different from what happened here, and if it was then subject to a billion years of evolution, who knows what we might find?

    It seems to me that life probably originated in biochemical replicators, chemical structures capable of making more of themselves. I have the gut feeling that more than one kind of replicator might be possible and might have seeded life somewhere.

    So, bottom line, I'm very pleased to see that the exobiologists are thinking in terms of life 'not as we know it'. That's what we are most likely to encounter out there, absent panspermia.
     
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  5. paddoboy Valued Senior Member

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    I'm also pleased that exobiologists are thinking in terms of "life as we don't know it", but can also understand why so far the search has concentrated on "life as we know it"
    I also maintain that an open mind needs to be kept on all possibilities, including Panspermia.
    Another article/paper to follow.....
     
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  7. paddoboy Valued Senior Member

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    http://www.sciencemag.org/content/347/6220/415.abstract

    Abstract:
    Reports of plumes or patches of methane in the martian atmosphere that vary over monthly time scales have defied explanation to date. From in situ measurements made over a 20-month period by the tunable laser spectrometer of the Sample Analysis at Mars instrument suite on Curiosity at Gale crater, we report detection of background levels of atmospheric methane of mean value 0.69 ± 0.25 parts per billion by volume (ppbv) at the 95% confidence interval (CI). This abundance is lower than model estimates of ultraviolet degradation of accreted interplanetary dust particles or carbonaceous chondrite material. Additionally, in four sequential measurements spanning a 60-sol period (where 1 sol is a martian day), we observed elevated levels of methane of 7.2 ± 2.1 ppbv (95% CI), implying that Mars is episodically producing methane from an additional unknown source.
     
  8. paddoboy Valued Senior Member

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    Methane Found on Mars, Indicates Life May Once Have Existed There: Nasa


    After an exhaustive analysis of data obtained during 605 Martian days, Nasa'sCuriosity rover has confirmed the presence of methane on Mars environment which may hint that life once existed on the Red Planet.

    The tunable laser spectrometer in the SAM (Sample Analysis at Mars) instrument of the Curiosity rover has unequivocally detected an episodic increase in the concentration of methane in Mars' atmosphere.

    This puts an end to the long controversy on the presence of methane in Mars, which started over a decade ago when this gas was first detected with telescopes from the Earth, the authors from the Mars Science Laboratory (MSL) reported.

    Since methane can be the product of biological activity - practically all the existing methane in the Earth's atmosphere originates in this way - this has created great expectations that Martian methane could also be of a similar origin.

    (Also See:Nasa Curiosity Rover Clicks New 'Mars Selfie' at Mojave Site)

    "It is a finding that puts paid to the question of the presence of methane in the Martian atmosphere but it does pose some other more complex and far-reaching questions, such as the nature of its sources," said study co-author Francisco Javier Martin-Torres from the Andalusian Institute of Earth Sciences (CSIC-UGR) at the University of Granada, Spain.

    "The sources, we believe, must lie in one or two additional sources that were not originally contemplated in the models used so far. Among these sources, we must not rule out biological methanogenesis," he added.

    According to some current models, if there really existed methane in Mars, it would remain there for an average 300 years and during this period, it would be homogeneously distributed across the atmosphere.

    SAM has been detecting basal levels of methane concentration and has confirmed an event of episodic increase of up to 10 times this value during a period of 60 Martian days.

    The new data are based on observations during almost one Martian year (almost two Earth years), included in the initial prediction for the duration of the mission (nominal mission), during which Curiosity has surveyed about 8 kms in the basin of the Gale crater.

    The newly arrived MAVEN (Mars Atmosphere and Volatile Evolution) from Nasa will provide continuity for the study of this subject, the US space agency said in a statement.

    In the near future, the Trace Gas Orbiter (TGO), jointly developed by the European Space Agency (ESA) and the Russian Space Agency (Ruscosmos) will measure the concentration of methane on Mars at a larger scale.

    The paper was published in the journal Science.
    http://gadgets.ndtv.com/science/new...indicates-life-once-existed-there-nasa-665701
     
  9. Daecon Kiwi fruit Valued Senior Member

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    Let's hope these lifeforms have no sense of smell...
     
  10. Enmos Valued Senior Member

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    Methane is odorless

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  11. Yazata Valued Senior Member

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    http://www.scientificamerican.com/a...mical-on-titan-could-allow-it-to-harbor-life/

    It all centers around a hydrocarbon called acrylonitrile that's already known to exist on Saturn's moon Titan, an almost earthlike place with a thick atmosphere, mountains, rivers and seas (of liquid methane). The big difference between here and there is temperature, Titan's average surface temperature is a chilly -179C.

    Investigating the chemistry possible in such a place, scientists at Cornell have discovered that acrylonitrile can form membranes with characteristics very similar to cell (and nuclear and mitochondrial) membranes on Earth. What's more, computer simulations suggest that these membranes will form into hollow balls (the investigators call them azotosomes).

    Modeling the formation of cell membranes and cell-like vesicles is a long way from modeling life, with its genetic, metabolic and reproductive functions. But it does suggest a way that chemically exotic life might have gotten a start in alien environments.
     
    Last edited: Mar 3, 2015
  12. exchemist Valued Senior Member

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    Methane doesn't smell of much.

    That's why they have to put stenching agents (mercaptans, I think) into commercial gas supplies, as a safety measure so we can smell leaks.
     
  13. exchemist Valued Senior Member

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    Yes I always felt that too, but as I learnt more chemistry had to reconcile myself to what this tells us about the most likely candidates. It is very hard to envisage anything that does not make use of the unique catenation properties of carbon, for example, especially given its widespread cosmic abundance - and I see that these chemists also assume carbon is the basis of this alternative life concept. What they are doing, though, is exploring an alternative solvent to water, which is interesting. I can't help thinking a solvent which is not polar will have limitations, but it is interesting at any rate than they have managed to find a workable cell membrane for a methane-solvent world.

    (Having mentioned the W word, I expect Wellwisher will now arrive, to give us one of his brain-of-Pooh expositions on H bonding, entropy, liberals, etc.

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  14. Daecon Kiwi fruit Valued Senior Member

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    Oh, I didn't know that. Cool.

    So if it's not methane, what causes the "rotten egg" smell?
     
  15. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    Sulfur compounds in the methane gas.

    "Mercaptan is less corrosive and less toxic than similar sulfur compounds found naturally in rotten eggs, onions, garlic, skunks, and, of course, bad breath. In other words, forms of mercaptan can be found in things that smell." https://www.columbiagasohio.com/stay-safe/what-to-do-when-you-smell-gas/what-is-mercaptan-
     
  16. Daecon Kiwi fruit Valued Senior Member

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    Oh, neat. I learned something new today.

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  17. paddoboy Valued Senior Member

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    Great stuff
     

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