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Thread: Phosphine, a strong biosignature, has been detected in the atmosphere of Venus

  1. #91
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    Quote Originally Posted by Noclevername View Post
    Earth life has surprised us in this regard before, showing up in places where we thought it couldn't possibly survive. Extremophiles, life that harvests energy in uncommon ways, we didn't know until we found them.
    Earth-life has evolved alongside an (evidenced) abundant, ubiquitous water supply, whereas Venus' hypothesised water analogy is purely model dependent.
    Water facilitates life's evolvability (and adaption), so the argument that speculated Venusian life evolved and adapted to present-day conditions, is also purely model dependent and lacking in an accurate (objective) Venusian context.

    Quote Originally Posted by Noclevername
    Let's go find out what's really there. Design and send probes that actually examine in detail the atmosphere at the level where phosphene was found.
    'Unknown' is the accurate (and honest) basis for initiating such investigatory missions.
    Venusian life-searching missions however, are based on pure speculation.

  2. #92
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    Quote Originally Posted by Selfsim View Post
    Earth-life has evolved alongside an (evidenced) abundant, ubiquitous water supply, whereas Venus' hypothesised water analogy is purely model dependent.
    Water facilitates life's evolvability (and adaption), so the argument that speculated Venusian life evolved and adapted to present-day conditions, is also purely model dependent and lacking in an accurate (objective) Venusian context.

    'Unknown' is the accurate (and honest) basis for initiating such investigatory missions.
    Venusian life-searching missions however, are based on pure speculation.

    Tests designed to find out if there is life, are honestly a good basis for a probe. The results of those tests, will give us something to talk about. Until then it's all speculation. Including your conclusions.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  3. #93
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    Quote Originally Posted by Selfsim View Post
    Sigh ..

    No need for me withdraw anything, as what I said was: there is (now) evidence of its implausibility .. not the least of which is:

    (i) the decreased levels of phosphine subsequently announced by Greaves etal, due to the original errored (uncalibrated?) raw data (now down to only several ppb),
    (ii) the exothermic nature of the 2SO₃ + 4H₂O → 2H₂SO₄+ H₂O. reaction and its effect on any active biochemistry and;
    (iii) the known highly corrosive effects of H₂SO₄ on organic matter.
    H₂SO₄ is destructive to some organic compounds, but by no means to all of them. As the eminent chemist Ronald J. Gillespie observed back in 1959: "anhydrous sulfuric acid... is a good solvent for a wide variety of organic compounds, very many of which give stable solutions, from which they may be recovered unchanged".

  4. #94
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    Quote Originally Posted by Noclevername View Post
    Tests designed to find out if there is life, are honestly a good basis for a probe.
    In the case of Venus, please cite the specific probe tests which would permit constraining a conclusion to 'life' or 'no life'.

    Quote Originally Posted by Noclevername
    Until then it's all speculation. Including your conclusions.
    Which conclusions do you refer to there, specifically?

  5. #95
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    Quote Originally Posted by Colin Robinson View Post
    H₂SO₄ is destructive to some organic compounds, but by no means to all of them. As the eminent chemist Ronald J. Gillespie observed back in 1959: "anhydrous sulfuric acid... is a good solvent for a wide variety of organic compounds, very many of which give stable solutions, from which they may be recovered unchanged".
    Can you please list the plausible bio-active organic compounds?

  6. #96
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    Quote Originally Posted by Selfsim View Post
    Can you please list the plausible bio-active organic compounds?
    I won't attempt to list all of them, but here are three categories for a start:

    1. Compounds containing oxidised sulfur

    Carbon chains linked to the sulfate (SO₄) functional group, a fragment of the sulfuric acid molecule, are known as organosulfates or sulfate esters. They are analogous to carbohydrates, which contain fragments of the water molecule. But compared to carbohydrates, organosulfates are weaker bases and stronger acids, and therefore more likely to occur in an acidic environment.

    Sulfonic acids and sulfonates are a related class of compounds with one less oxygen atom in each functional group. Organosulfates and sulfonates are found in soils here on Earth, and play a part in sulfur cycling. The sulfonic acid taurine is present in the bodies of all living things with complex cells (eukaryotes), including us humans.

    2. Compounds with alkene bonds

    The alkene group consists of two carbon atoms with a double bond (C=C). In sulfuric acid solution, the alkene group behaves similarly to the carbonyl (C=O) group in water solution, enabling synthesis of long chains of carbon atoms out of shorter chains. (See The Limits of Organic Life in Planetary Systems, National Research Council, Washington 2007. Chapter 6, Section 6.2.1.2)

    3. Carbon chains which also include silicon atoms

    Carbon chain compounds which incorporate silicon atoms in the chain are well known to chemists. However, they are unstable in water, and are seldom if ever used by Earth life. As Janusz Petkowski, William Bains and Sara Seager recently found, these compounds are more stable in sulfuric acid, and have properties which could be useful for life, such as enabling movement of electrons along the chain.

  7. #97
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    Quote Originally Posted by Colin Robinson
    .. here are three categories for a start
    Noted that you shifted to generalised compound categories, rather than the more specific and narrowly focused bio-active compounds in my original query.
    Quote Originally Posted by Colin Robinson
    1. Compounds containing oxidised sulfur
    ..
    The sulfonic acid taurine is present in the bodies of all living things with complex cells
    Taurine is biosynthesized by the enzymatic modification of proteins following protein biosynthesis. It is also a product of the transsulfuration metabolic pathway.

    So, how can the protein biosynthesis and metabolic bio-active precursor processes, needed by life to produce such sulfonic acids, plausibly function in Venus’ concentrated atmospheric sulfuric acid (given that such precursor processes rely on the presence of water -ie: cytoplasm’s key constituent)?
    Quote Originally Posted by Colin Robinson
    2. Compounds with alkene bonds
    These are more generalised classes of organic molecules and not the more specific bio-active compounds specified in my original query.
    This is akin to an organic chemistry ‘algebra error’ to me, unfortunately(?)
    Quote Originally Posted by Colin Robinson
    3. Carbon chains which also include silicon atoms
    It seems you are attempting to manufacture a life-as-we-don’t-know-it (LAWDKI) solution .. which is ok .. but when discussing the evidence of plausibility, LAWDKI explanations tend to produce a major plausibility nose-dive in comparison with non-life explanations for Venus’ reported trace levels of atmospheric phosphine.

  8. #98
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    Quote Originally Posted by Selfsim View Post
    Noted that you shifted to generalised compound categories, rather than the more specific and narrowly focused bio-active compounds in my original query.
    You want me to list every individual compound which could be "bio-active"?

    Why aren't generalised compound categories enough to back up the general idea that something may be growing and reproducing in Venus' clouds?

    Taurine is biosynthesized by the enzymatic modification of proteins following protein biosynthesis. It is also a product of the transsulfuration metabolic pathway.

    So, how can the protein biosynthesis and metabolic bio-active precursor processes, needed by life to produce such sulfonic acids, plausibly function in Venus’ concentrated atmospheric sulfuric acid (given that such precursor processes rely on the presence of water -ie: cytoplasm’s key constituent)?
    Sounds like you don't just want a list of specific compounds, you also want a complete metabolic path to get to each compound...

    It seems you are attempting to manufacture a life-as-we-don’t-know-it (LAWDKI) solution ..
    The clouds of Venus contain H2SO4 at concentrations which occur on Earth only in artificial situations, e.g. chemical laboratories. If something is growing and reproducing there, I'd expect it to be chemically somewhat different from life on Earth.

    which is ok .. but when discussing the evidence of plausibility, LAWDKI explanations tend to produce a major plausibility nose-dive in comparison with non-life explanations for Venus’ reported trace levels of atmospheric phosphine.
    What are your non-life explanations for Venus' reported phosphine?
    Last edited by Colin Robinson; 2020-Dec-20 at 09:07 AM.

  9. #99
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    Quote Originally Posted by Selfsim View Post
    In the case of Venus, please cite the specific probe tests which would permit constraining a conclusion to 'life' or 'no life'.

    Which conclusions do you refer to there, specifically?
    As already addressed, I cannot design tests. It's a strawman to put the burden of doing so on an amateur.

    And you always draw the same conclusion in these LIS threads, so if you don't know what that is, it may entail some self-reflection.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  10. #100
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    Quote Originally Posted by Noclevername View Post
    As already addressed, I cannot design tests. It's a strawman to put the burden of doing so on an amateur.
    And in years past we have discussed the limitations of present technology life tests on probes, like those on, for instance, the Viking Mars landers. Given mass limits and complexity, it is possible to do certain specific tests, but it isn’t like a general laboratory where many things can be tested as different research routes are suggested. That’s why sample return becomes important. Alternatively, there could be a series of experiments on different probes done over a period of years, depending on prior experimental results. In either case, it is unreasonable to ask for a specific probe test. I wouldn’t expect subject matter experts to answer such a leading question.

    And you always draw the same conclusion in these LIS threads, so if you don't know what that is, it may entail some self-reflection.
    Yes, and absolute negativity when discussing questions like these is as unscientific as absolute positivity. Whether there is life or not in the Venusian atmosphere, it isn’t going to be determined on a discussion board.
    Last edited by Van Rijn; 2020-Dec-20 at 08:32 PM. Reason: spelling and clarification

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