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Thread: Testable predictions about life on Titan

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    Testable predictions about life on Titan

    From the thread "What do you think is the most likely explanation for the Fermi paradox"

    Quote Originally Posted by Selfsim View Post
    (Perhaps a more interesting topic) but what happens to mold spores in conditions such as Titan's?
    According to Chris McKay, there is extremely low risk of Titan's surface getting contaminated by organisms from Earth, or vice versa. Conditions are too different. He mentions this in the conclusion of his concept paper Titan as the abode of life

    What kind of testable predictions does McKay's methanogen hypothesis make?
    McKay didn't actually originate the methanogen hypothesis. But yes, he has developed testable predictions from it.

    1. Methanogens, if present, will affect levels of H2 in the atmosphere. Where methanogens are active, H2 levels will be lower.
    2. Life chemistry on Titan (as on Earth) will favour the formation of the specific organic molecules it has a use for. Because of this, a graph showing relative abundance of different organics will have spikes in it, rather than being a smooth curve.

    What are his predicted impacts the drone will have on his hypothetical methanogen?
    As I understand it, he doesn't expect any impact on their overall population, if they are there.

    If they can grow and reproduce in liquid methane and/or ethane, they have plenty of available habitat. Which won't be diminished (or extended) by a small scientific drone mission.

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    Quote Originally Posted by Colin Robinson View Post
    According to Chris McKay, there is extremely low risk of Titan's surface getting contaminated by organisms from Earth, or vice versa. Conditions are too different. He mentions this in the conclusion of his concept paper Titan as the abode of life
    As is typical of McKay, his bold assertions about the topic are unsupported in evidence. His exact words in that conclusion are:
    Quote Originally Posted by McKay
    In contrast, possibilities of contamination of Titan with water-based life from Earth are essentially zero ..
    .. so where is his (chemical) evidence about what happens when dormant, say dessicated, mold spores are released into a Titan-like physical environment? I don't think anyone has considered that (or at least, I've never seen anything on that .. Have you?)
    Last I heard, Titan is believed to be composed of half water ice, has subsurface liquid water/ammonia eutectic magma mixtures and trace stratospheric water vapour(?) Why wouldn't reactivation occur under certain conditions if those physical conditions do in fact exist on Titan? Why would his above 'prediction' rule that out (if it wasn't just all his opinion?)

    Quote Originally Posted by Colin Robinson
    McKay didn't actually originate the methanogen hypothesis. But yes, he has developed testable predictions from it.
    He's certainly also responsible for hyping it ..

    Quote Originally Posted by Colin Robinson
    1. Methanogens, if present, will affect levels of H2 in the atmosphere. Where methanogens are active, H2 levels will be lower.
    Depends on the abundance of said hypotheticals ... and 'lower' compared with what exactly?

    If they're of sufficient abundance to affect H2 levels in the atmosphere, shouldn't we also be able to get direct visual evidence of them with say, DragonFly cameras? Why doesn't his hypothesis also 'predict' that?

    Its all just speculative musing .. with virtually nothing but faith in the existence of some McKay concoted hypothetical Titan life-form backing it all up.
    What are his predicted error bars on H2 variations where life might not be inferred?
    I mean .. even the Electric Universe and Creationist folk can come up with better 'predictions' than that!

    Quote Originally Posted by Colin Robinson
    2. Life chemistry on Titan (as on Earth) will favour the formation of the specific organic molecules it has a use for. Because of this, a graph showing relative abundance of different organics will have spikes in it, rather than being a smooth curve.
    What sort of a 'prediction' is that?
    'Spikes'? Are you/he serious? 'Spikes'? Hilarious!
    (Note: I don't mean to be mean to you here if you're just interpreting 'predictions' from his musings .. Are they his predictions or just his musings? .. I'm not entirely clear on this).

    Quote Originally Posted by Colin Robinson
    As I understand it, he doesn't expect any impact on their overall population, if they are there. If they can grow and reproduce in liquid methane and/or ethane, they have plenty of available habitat. Which won't be diminished (or extended) by a small scientific drone mission.
    I was more pondering the impact of stowaway mold spores on the DragonFly's science (organics) measurements in, specifically, a Titan environment .. (ie: false positives of detection of his methanogen increased or decreased as a result?) .. (Admittedly my question wasn't at all clear on that though ...)

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    Quote Originally Posted by Selfsim View Post
    As is typical of McKay, his bold assertions about the topic are unsupported in evidence. His exact words in that conclusion are:.. so where is his (chemical) evidence about what happens when dormant, say dessicated, mold spores are released into a Titan-like physical environment? I don't think anyone has considered that (or at least, I've never seen anything on that .. Have you?)
    Last I heard, Titan is believed to be composed of half water ice, has subsurface liquid water/ammonia eutectic magma
    "Magma" is right. If Titan has subsurface liquid water, it is not only subsurface but subcrust, like liquid rock on Earth.

    mixtures and trace stratospheric water vapour(?) Why wouldn't reactivation occur under certain conditions if those physical conditions do in fact exist on Titan? Why would his above 'prediction' rule that out (if it wasn't just all his opinion?)
    The paper I linked to is about the surface of Titan as a habitat for life. It is much colder than the surface of Mars, too cold for liquid water, and is not an environment where an organism (such as mould) whose cells contained liquid water could grow and reproduce.

    Could something from Earth grow and reproduce if it found its way to Titan's magma? That's another question.

    'lower' compared with what exactly?
    ... lower compared to other regions of the atmosphere, e.g. high above the surface.

    If they're of sufficient abundance to affect H2 levels in the atmosphere, shouldn't we also be able to get direct visual evidence of them with say, DragonFly cameras? Why doesn't his hypothesis also 'predict' that?
    Consider phytoplankton here on Earth. They're of sufficient abundance to affect levels of O2 and CO2 in the atmosphere, but without a microscope the only direct visual evidence is the green tinge they give to sea water. Which is only visual evidence if you already had reason to think they use a green compound such as chlorophyl as a catalyst. How to predict what sort of colour, if any, Titan organisms would impart to the surface liquids?

    Even using a microscope, it can be difficult to distinguish microbes from mineral particles, especially when you don't know what the local minerals look like under a microscope.

    What sort of a 'prediction' is that?
    'Spikes'? Are you/he serious? 'Spikes'? Hilarious!
    Why do you find that hilarious? Is it because the word "spikes" has only one syllable, and you think multi-syllable words sound more scientific?

    (Note: I don't mean to be mean to you here if you're just interpreting 'predictions' from his musings .. Are they his predictions or just his musings? .. I'm not entirely clear on this).
    They're not just musings, and they're not just his.

    As he mentions, James Lovelock has pointed out that life chemistry is very selective in the molecules it produces and uses, compared to non-living chemistry. Two molecules which are chemically very similar can be produced in very different amounts by a biochemical system.

    He is not making predictions in the everyday sense, though. He is NOT saying that the graph of Titan's chemical compounds WILL be spiky rather than smooth. He is arguing that IF there's life on the surface of Titan THEN we can expect a spiky graph for chemical compounds instead of a smooth curve.

    I was more pondering the impact of stowaway mold spores on the DragonFly's science (organics) measurements in, specifically, a Titan environment .. (ie: false positives of detection of his methanogen increased or decreased as a result?) .. (Admittedly my question wasn't at all clear on that though ...)
    I can't see how stowaway mould spores would affect measurements of atmospheric hydrogen. And considering the amount of carbon compounds on Titan (they are much more abundant there than on Mars), I doubt that a few mould spores would much affect measurements of the relative quantities of different carbon compounds.
    Last edited by Colin Robinson; 2019-Jun-30 at 10:54 AM.

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    Reading with great interest.

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    No life on Titan expert here (either?), but if life is on Titan, as say, some kind of a facsimile of extreme sub-zero microbes, then life is most likely probable on all the other top contenders such as Mars, Europa, Enceladus, others such as Pluto & Ceres.

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    Quote Originally Posted by Colin Robinson View Post
    "Magma" is right. If Titan has subsurface liquid water, it is not only subsurface but subcrust, like liquid rock on Earth.
    ...
    The paper I linked to is about the surface of Titan as a habitat for life. It is much colder than the surface of Mars, too cold for liquid water, and is not an environment where an organism (such as mould) whose cells contained liquid water could grow and reproduce.

    Could something from Earth grow and reproduce if it found its way to Titan's magma? That's another question.
    Well its another question .. so for what reason would McKay rule it out in his blanketing, all encompassing, and obviously carelessly made statement, if he is not just full of speculatively motivated premises?
    The cryovolcano mechanism is also thought to bring the mixture to the surface .. and in some models, its a continuous process for replenishing the atmospheric methane.
    McKay appears as leaning towards being a 'woo-cowboy' who jumps ahead of the step-by-step methodical process of categorisation of the overall mission of exploration of new planetary environments.

    Quote Originally Posted by Colin Robinson
    ... lower compared to other regions of the atmosphere, e.g. high above the surface.
    And where's your evidence for supporting that?


    Quote Originally Posted by Colin Robinson
    Consider phytoplankton here on Earth. They're of sufficient abundance to affect levels of O2 and CO2 in the atmosphere, but without a microscope the only direct visual evidence is the green tinge they give to sea water. Which is only visual evidence if you already had reason to think they use a green compound such as chlorophyl as a catalyst. How to predict what sort of colour, if any, Titan organisms would impart to the surface liquids?
    No one would expect colors to be predictable .. but some surface visual evidence would have to be present somewhere where some 'hypothetical' atmosphere-affecting methanogen might be present (where its based on earth-life characteristics) .. and all one would therefore need, is camera capable of noticing it.

    Quote Originally Posted by Colin Robinson
    Even using a microscope, it can be difficult to distinguish microbes from mineral particles, especially when you don't know what the local minerals look like under a microscope.
    So you just blew away the need for a microscope because it doesn't sufficiently support the need for distinguishing McKay's 'might be there', yet testable, speculative microbes from minerals?

    Quote Originally Posted by Colin Robinson
    Why do you find that hilarious? Is it because the word "spikes" has only one syllable, and you think multi-syllable words sound more scientific?
    I'm not the subject here .. McKay's claim is .. was it his word, or did it come from somewhere else? Where's his evidence for such an obviously ludicrous mythical 'graph showing relative abundance of organics' claim?

    Quote Originally Posted by Colin Robinson
    They're not just musings, and they're not just his.
    So his woo has already propagated to others then? Before the basic surface surveys have even started then? And that's what he thinks is 'being scientific'?

    Quote Originally Posted by Colin Robinson
    As he mentions, James Lovelock has pointed out that life chemistry is very selective in the molecules it produces and uses, compared to non-living chemistry. Two molecules which are chemically very similar can be produced in very different amounts by a biochemical system.
    James Lovelock was speaking about Earth-life chemistry .. supported from evidence taken from Earth's biosphere .. Not some speculative 'Titan microbe' which relies solely on hijacking that term, and its definition, by taking it out of its contextual basis of evidence.

    Quote Originally Posted by Colin Robinson
    He is not making predictions in the everyday sense, though. He is NOT saying that the graph of Titan's chemical compounds WILL be spiky rather than smooth. He is arguing that IF there's life on the surface of Titan THEN we can expect a spiky graph for chemical compounds instead of a smooth curve.
    So all he's doing is arguing then(?) .. and not getting on with doing science. He's an arguer then .. and not being a scientist.

    Quote Originally Posted by Colin Robinson
    I can't see how stowaway mould spores would affect measurements of atmospheric hydrogen. And considering the amount of carbon compounds on Titan (they are much more abundant there than on Mars), I doubt that a few mould spores would much affect measurements of the relative quantities of different carbon compounds.
    Well using Curiosity's SAM organics lab's mass spectrometer sensitivity as a guideline, I think you may be mistaken about that. If a mould spore turned up in the sampling chain somehow I don't think it'd have much trouble picking it up by its organic mass difference from the background levels .. We can all imagine the hype that would then ensue ... (Which of course would, hypothetically speaking, then clearly demonstrate McKay etal's non-scientific purpose ...)

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    Quote Originally Posted by Spacedude View Post
    No life on Titan expert here (either?), but if life is on Titan, as say, some kind of a facsimile of extreme sub-zero microbes, then life is most likely probable on all the other top contenders such as Mars, Europa, Enceladus, others such as Pluto & Ceres.
    Yes .. that's an argument consistent with McKay's.
    So why isn't there visible evidence of it on Mars? Which is of course a rhetorical question .. (just staying consistent with McKay's own logical line of argument here) .. because its pretty clear that even IF its not found underground by sub-surface drilling .. they'll be more ​excuses reasoning for why it wasn't .. and so the existence of the speculative/hypothetical martian life-form meme continues forever ..

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    Quote Originally Posted by Spacedude View Post
    No life on Titan expert here (either?), but if life is on Titan, as say, some kind of a facsimile of extreme sub-zero microbes, then life is most likely probable on all the other top contenders such as Mars, Europa, Enceladus, others such as Pluto & Ceres.
    Because all these places seem to have subsurface liquid water?

    The thing is, Titan not only has subsurface water, it also has a much thicker atmosphere than any of the places you've mentioned. The upper atmosphere is chemically very active, and generates an energy-rich mixture of hydrogen and organic compounds. Plus, Titan has stable bodies of liquid (rivers, lakes, seas) on its surface, which are composed of liquid methane and ethane. And liquid precipitation in its atmosphere (rain, fog, etc) which feeds the rivers and lakes.

    These features make it a natural chemical laboratory unique in the solar system, whether there is life there on not.

    If it has living things in its subsurface liquid water, they might be chemically somewhat like the low-temperature Earth microbes you mentioned.

    But there's also the possibility of living things at the surface, which would need to be chemically quite different.

    Although all living things on Earth depend on liquid water to do their internal chemistry, scientists have long been interested in the idea of a different liquid (or combination of liquids) having a comparable function somewhere else. Titan's surface is a test case for this idea.

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    Quote Originally Posted by Selfsim View Post
    So all he's doing is arguing then(?) .. and not getting on with doing science. He's an arguer then .. and not being a scientist.
    Do you think that developing a logical argument isn't part of science?

    Is science (in your view) just a matter of making general observations, never considering the implications of what your observe, never developing and testing a hypothesis about it?

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    Examples

    Quote Originally Posted by Colin Robinson View Post
    Do you think that developing a logical argument isn't part of science?

    Is science (in your view) just a matter of making general observations, never considering the implications of what your observe, never developing and testing a hypothesis about it?
    How many observations of life on Titan do you have?
    I'm not a hardnosed mainstreamer; I just like the observations, theories, predictions, and results to match.

    "Mainstream isn’t a faith system. It is a verified body of work that must be taken into account if you wish to add to that body of work, or if you want to change the conclusions of that body of work." - korjik

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    Now we can't be entirely sure ... but I think the dude in glasses in this link might be McKay(?)



    .. Oh well .. at least that's testable without having ta go ta Titan, I suppose(?)

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    Quote Originally Posted by John Mendenhall View Post
    How many observations of life on Titan do you have?
    No direct observations of life on Titan. But the Cassini-Huygens mission made observations of some very intriguing phenomena there, for which presence of life is one possible explanation.

    One of these has to do with the liquid ethane (C2H6) on the surface. Not that fact that liquid ethane has been detected there — scientists were expecting that, even before the Cassini-Huygens mission reached the Saturn system in December 2004. The puzzling bit is how much liquid ethane there is, or rather, how much there isn't.

    It's kinda like the detective story of the dog that didn't bark...

    Planetary scientists knew that Titan's upper atmosphere produces ethane, they had a reasonable idea of the rate of production, they also knew that the ethane would precipitate to the surface and build up there. So they multiplied the rate of ethane production by the age of Titan, and concluded that there would be enough liquid ethane on the surface to form a global ocean. Guess what? There isn't one. Hydrocarbon lakes and rivers, yes. But a global ocean, no.

    There are several possible explanations for this, each of which has its problems. For instance:

    1. Titan's atmosphere has been producing ethane for a length of time much shorter than the age of Titan, because the atmosphere itself was generated quite recently. This hypothesis has been taken quite seriously by planetary scientists, including Chris McKay. Problem: Since this hypothesis was put forward, studies about Titan's atmosphere concluded that it is not recent, it is as old as Titan itself.

    or

    2. Non-living chemical reactions are taking place on the surface, adding hydrogen to ethane and other hydrocarbons to get methane, which can then evaporate into the atmosphere. Problem: How does such a chemical reaction take place at the low temperatures found at Titan's surface? As McKay notes, it would be a startling discovery to find a non-living catalyst which could enable this, though not as startling as finding that the third hypothesis is right.

    or

    3 Chemical reactions are taking place, hydrogenating ethane and other hydrocarbons to get methane, and the catalytic agent is a population of living organisms. The reaction is exothermic, so could provide an organism with something all scientists agree that life requires — an energy source. The density of energy available that way seems to match the energy needs of bacteria-like organisms, whose energy inputs are modest compared to those of more complex living things. Problem: As sceptics keep reminding us, we have very little idea how something could grow and reproduce at Titan surface temperatures, in an environment where the predominant liquids are methane and ethane.
    Last edited by Colin Robinson; 2019-Jul-01 at 03:31 AM.

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    Quote Originally Posted by Colin Robinson View Post
    No direct observations of life on Titan. But the Cassini-Huygens mission made observations of some very intriguing phenomena there, for which presence of life is one possible explanation.

    One of these has to do with the liquid ethane (C2H6) on the surface. Not that fact that liquid ethane has been detected there — scientists were expecting that, even before the Cassini-Huygens mission reached the Saturn system in December 2004. The puzzling bit is how much liquid ethane there is, or rather, how much there isn't.

    It's kinda like the detective story of the dog that didn't bark...

    Planetary scientists knew that Titan's upper atmosphere produces ethane, they had a reasonable idea of the rate of production, they also knew that the ethane would precipitate to the surface and build up there. So they multiplied the rate of ethane production by the age of Titan, and concluded that there would be enough liquid ethane on the surface to form a global ocean. Guess what? There isn't one. Hydrocarbon lakes and rivers, yes. But a global ocean, no.

    There are several possible explanations for this, each of which has its problems. For instance:

    1. Titan's atmosphere has been producing ethane for a length of time much shorter than the age of Titan, because the atmosphere itself was generated quite recently. This hypothesis has been taken quite seriously by planetary scientists, including Chris McKay. Problem: Since this hypothesis was put forward, studies about Titan's atmosphere concluded that it is not recent, it is as old as Titan itself.

    or

    2. Non-living chemical reactions are taking place on the surface, adding hydrogen to ethane and other hydrocarbons to get methane, which can then evaporate into the atmosphere. Problem: How does such a chemical reaction take place at the low temperatures found at Titan's surface? As McKay notes, it would be a startling discovery to find a non-living catalyst which could enable this, though not as startling as finding that the third hypothesis is right.

    or

    3 Chemical reactions are taking place, hydrogenating ethane and other hydrocarbons to get methane ...
    So new minerals and compounds have recently been created in the lab under Titan-like conditions. Cassini observations also reveal 'rings' of unknown materials surrounding the lakes. See here for journo summary.
    Scientists re-creating Titan-esque conditions in their laboratory have discovered new compounds and minerals not found on Earth, including a co-crystal made of solid acetylene and butane.
    ...
    The first things to drop out of their Titan hydrocarbon soup were benzene crystals. Benzene is perhaps best known as a component of gasoline and is a snowflake-shaped molecule made out of a hexagonal ring of carbon atoms. But Titan benzene held a surprise: The molecules rearranged themselves and allowed ethane molecules inside, creating a co-crystal.

    The researchers then discovered the acetylene and butane co-crystal, which is probably a lot more common on Titan than benzene crystals, based on what's known about the moon's composition, Cable said.

    In the moon's cold climate, the acetylene-butane co-crystals might form rings around the moon's lakes as the liquid hydrocarbons evaporate and the minerals drop out—in the same way that salts can form crusts on the shores of Earth's lakes and seas, according to Cable.
    Geophysics thus predicts new compounds and minerals not found on Earth .. which deepens the investigation of (2) above .. in spite of McKay's personal, predicted 'enstartlement' about this option.

    Exactly what happens when these previously unforeseen mineral crystals interact with combined atmospherics/geology, is unknown (and will remain that way until properly formed scientific study is performed and demonstrated .. despite other scientifically undisciplined attempts to clutter up such unknowns).

    A similar unforeseen interaction between the martian surface chemistry and ionised methane is also now under active investigation to explain Mars' vanishing methane and its impact on any extant surface organics.

    Such useful and productive scientific research, shown in these examples, contrasts sharply with the 'wanting-in-quality' shoot-from-the-hip approach, (like McKay's).

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    Quote Originally Posted by Selfsim View Post
    So new minerals and compounds have recently been created in the lab under Titan-like conditions. Cassini observations also reveal 'rings' of unknown materials surrounding the lakes. See here for journo summary.
    Thanks for the link.

    Clearly we humans are on a learning curve about how organic molecules behave on Titan...

    The head of the group who created these co-crystals, Morgan Cable, is on the science and engineering team of the Dragonfly mission.

    Chris McKay's on that team too, by the way.

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    Quote Originally Posted by Spacedude View Post
    No life on Titan expert here (either?), but if life is on Titan, as say, some kind of a facsimile of extreme sub-zero microbes, then life is most likely probable on all the other top contenders such as Mars, Europa, Enceladus, others such as Pluto & Ceres.
    Titan is lousy with hydocarbons - the basis for life as we know it. That's what makes it a good candidate.

    Some of those you list also have huge amounts of hydrocarbons, but not all.

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    Quote Originally Posted by Colin Robinson View Post
    Clearly we humans are on a learning curve about how organic molecules behave on Titan...
    The noteworthy point here is that the study of one of the traditional 'possible biosign' organic compounds (methane gas), when examined more closely in a non-earthly (exo)environment, has shown us that it is capable of showing up in unexpected physical forms which are capable of actively transforming a landscape in unexpected ways.
    Its our expectation that must be adjusted here to accommodate the new findings .. and not the other way around. What does this tell us about how real or unreal our expectations (or so-called exo-life predictions) really are?

    Also, its therefore not just organic life that's capable of transforming a landscape. In a sense, we could be seeing a new category of 'landscape transforming conditions' of organic compounds, in which Earth's (evolving) environment may have just given us exposure to one specific, limited subset thereof. Its almost like we're completely oblivious to noticing the sheer diversity of combinations of physical variations of organic compounds and yet, the evidence of this, as we look around our own solar system, is glaringly obvious.

    Just contemplating this over the billions of years of evolution of some given, always changing, planetary geophysical environment, (I think), leads to virtually exponential degrees of complexity along with all its unimaginable permutation/combination implications.

    IMO, we should all bear this in mind when exploring what's out there ... and not just our own familar bag of organic Leggo building blocks.

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    Quote Originally Posted by Selfsim View Post
    The noteworthy point here is that the study of one of the traditional 'possible biosign' organic compounds (methane gas),
    Methane (CH4) is one of the many organic compounds found on Titan — the most common, and the simplest.

    when examined more closely in a non-earthly (exo)environment, has shown us that it is capable of showing up in unexpected physical forms which are capable of actively transforming a landscape in unexpected ways.
    Morgan Cable's co-crystals are not composed of forms of methane (CH4). They are composed of acetylene (C2H2), ethane (C2H6), butane (C4H10), and benzene (C6H6).

    Cable may not have expected the specific results he got. But why would he have performed the experiment in the first place, if he hadn't expected (or half-expected) that these substances would behave in significantly different ways in Titan-like conditions?

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    Quote Originally Posted by Colin Robinson View Post
    Morgan Cable's co-crystals are not composed of forms of methane (CH4). They are composed of acetylene (C2H2), ethane (C2H6), butane (C4H10), and benzene (C6H6).
    These species can be the products of photochemistry in Titan's atmosphere, induced by solar radiation and energy from Saturn's magnetosphere, which dissociates extant N2 and CH4, which then continue to cascade react as they fall through the Titan atmosphere. In this atmospheric model, the products would be deposited on the surface within the vicinity of, (or in), Titan's hydrocarbon lakes in the polar regions, and become exposed as the foreshore liquid evaporates. Cassini's VIMs direct observation of the 5-μm bright evaporite features on the lake shores could then be accounted for by this same mechanism.

    What's your point?


    Quote Originally Posted by Colin Robinson
    Cable may not have expected the specific results he got. But why would he have performed the experiment in the first place, if he hadn't expected (or half-expected) that these substances would behave in significantly different ways in Titan-like conditions?
    He'd been investigating the above geophysical process model.

    The proposed co-crystals are now predictions of that model .. backed up by lab test objective evidence and VIMs observations.

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    Quote Originally Posted by Selfsim View Post
    These species can be the products of photochemistry in Titan's atmosphere, induced by solar radiation and energy from Saturn's magnetosphere, which dissociates extant N2 and CH4, which then continue to cascade react as they fall through the Titan atmosphere. In this atmospheric model, the products would be deposited on the surface within the vicinity of, (or in), Titan's hydrocarbon lakes in the polar regions, and become exposed as the foreshore liquid evaporates. Cassini's VIMs direct observation of the 5-μm bright evaporite features on the lake shores could then be accounted for by this same mechanism.
    Is that a cut-and-paste from Cable's paper?

    Anyway, it is not the same as saying that they are methane in "unexpected physical forms" as you wrote in your earlier message.

    He'd been investigating the above geophysical process model.
    An example which shows that working with models (developing and investigating them) is a normal part of science. Science is therefore not just a process of observing and cataloguing, as you told us the other day...

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    Quote Originally Posted by Colin Robinson View Post
    Is that a cut-and-paste from Cable's paper?
    The content references the 2019 Planetary Science Conference paper .. but so what? Perhaps a sci-fi story is expected?
    Quote Originally Posted by Colin Robinson
    Anyway, it is not the same as saying that they are methane in "unexpected physical forms" as you wrote in your earlier message.
    That's it? .. That's your point? How do think an unexpected 'physical form' comes about? Magic?

    Quote Originally Posted by Colin Robinson
    An example which shows that working with models (developing and investigating them) is a normal part of science. Science is therefore not just a process of observing and cataloguing, as you told us the other day...
    Science is defined by its texbook documented, and its widely taught process (as you have had demonstrated to you many, many times over, now). No human can perform cognitive functions without models. Why would you ever think a scientifically thinking mind would exclude models?

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    Quote Originally Posted by Selfsim View Post
    Also, its therefore not just organic life that's capable of transforming a landscape. In a sense, we could be seeing a new category of 'landscape transforming conditions' of organic compounds, in which Earth's (evolving) environment may have just given us exposure to one specific, limited subset thereof... Just contemplating this over the billions of years of evolution of some given, always changing, planetary geophysical environment, (I think), leads to virtually exponential degrees of complexity along with all its unimaginable permutation/combination implications.
    Yes, it is possible that Earth's biosphere belongs to a subset of a larger category. The word "chemosphere" comes to mind for a region where organic compounds are forming, interacting, going into and out of liquid solution, and transforming the landscape...

    We know Titan has a chemosphere. We don't know whether or not its chemosphere is in the biosphere subset.

    It's a scientific treasure either way.

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    Quote Originally Posted by Colin Robinson View Post
    Yes, it is possible that Earth's biosphere belongs to a subset of a larger category. The word "chemosphere" comes to mind for a region where organic compounds are forming, interacting, going into and out of liquid solution, and transforming the landscape...
    It seems that term is already reserved and has the meaning of an upper region of the atmosphere where specifically photochemistry is occurring, (Atmospheric physics), from the AMS Meteorology Glossary:
    The vaguely defined region of the upper atmosphere in which photochemical reactions take place.

    It is generally considered to include the stratosphere (or the top thereof) and the mesosphere, and sometimes the lower part of the thermosphere. This entire region is the seat of a number of important photochemical reactions involving atomic oxygen O, molecular oxygen O2, ozone O3, hydroxyl OH, nitrogen N2, sodium Na, and other constituents to a lesser degree.
    I don't see how landscape interactions can be part of the upper atmosphere region where specifically photochemistry is occurring?
    Photochemistry is a specific physical process and is obviously distinct from what happens on a lake shore in the case of evaporites.

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    Quote Originally Posted by Selfsim View Post
    It seems that term is already reserved and has the meaning of an upper region of the atmosphere where specifically photochemistry is occurring,
    I didn't know that... It turns out that "chemosphere" has a couple of other meanings as well. It's the name of a journal about environmental chemistry, for instance.

    (Atmospheric physics), from the AMS Meteorology Glossary:
    I don't see how landscape interactions can be part of the upper atmosphere region where specifically photochemistry is occurring?
    Photochemistry is a specific physical process and is obviously distinct from what happens on a lake shore in the case of evaporites.
    Isn't it just as obvious that I was using the term in a different sense?

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    Speaking of how words are used, you asked earlier in this thread about Chris McKay's use of "spike"...

    Quote Originally Posted by Selfsim View Post
    ... was it his word, or did it come from somewhere else?
    One of the definitions of "spike" in The Free Dictionary:

    "7.a. A sharp rise followed by a sharp decline in a graph or in the tracing of a scientific instrument."

    This is the sense in which McKay used the term in his concept paper about Titan as an abode for life.

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    Quote Originally Posted by Colin Robinson View Post
    Speaking of how words are used, you asked earlier in this thread about Chris McKay's use of "spike"...
    You're bogged down in semantics here.

    The laughable point is about McKay's supposedly humungously earth-shattering 'prediction'.

    See the attachment which shows real-life GCMS (SAM) plots of the martian Cumberland mudstone sample and then try and argue that predicting 'spikes' in a relative abundance graph of organics in some sample as being 'evidence of life', is anything other than just pure linguistic rubbish!
    Attached Images Attached Images

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    Quote Originally Posted by Selfsim View Post
    You're bogged down in semantics here. The laughable point is about McKay's supposedly humungously earth-shattering 'prediction'.
    I'm glad you're no longer objecting to the word "spikes" in itself. That indicates to me that you are no longer bogged down in semantics.

    See the attachment which shows real-life GCMS (SAM) plots of the martian Cumberland mudstone sample and then try and argue that predicting 'spikes' in a relative abundance graph of organics in some sample as being 'evidence of life', is anything other than just pure linguistic rubbish!
    (Deep breath)

    McKay's point is not simply about "a relative abundance graph of organics". It is about relative abundance of chemically related organics. Related, in the sense that e.g. two different amino acids with similar numbers of carbon atoms are related.

    The spikes in your attachment would be relevant IF you could show that the low points between them correspond to abundance of molecules that are related (as closely as two amino acids) to molecules whose abundance is indicated by the spikes.

    McKay's prediction may or may not be earth-shattering, but at least it is testable...
    Last edited by Colin Robinson; 2019-Jul-05 at 07:53 AM.

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    Quote Originally Posted by Colin Robinson
    2. Life chemistry on Titan (as on Earth) will favour the formation of the specific organic molecules it has a use for. Because of this, a graph showing relative abundance of different organics will have spikes in it, rather than being a smooth curve.
    ...
    Quote Originally Posted by Colin Robinson
    McKay's point is not simply about "a relative abundance graph of organics". It is about relative abundance of chemically related organics. Related, in the sense that e.g. two different amino acids with similar numbers of carbon atoms are related.

    The spikes in your attachment would be relevant IF you could show that the low points between them correspond to abundance of molecules that are related (as closely as two amino acids) to molecules whose abundance is indicated by the spikes.

    McKay's prediction may or may not be earth-shattering, but at least it is testable...
    This is such a dumb ‘prediction’, its hard to know where to start.

    A sample taken from Titan’s surface tholins is already expected to contain, (for eg), amino acids. Determining the presence of such molecules firstly requires classifying by molecular weight (using a mass spectrometer), but this is by no means sufficient for determining whether or not such molecules are actually biomolecules. Tholins are already known to contain many different structural isomers for a given mass molecule, so determining the isomers is vital before concluding biologically relevant content (biomolecules).

    So, any measure of McKay’s ‘relative abundance of different organics’ in a Titan sample, is already expected to include a wide variety of non biomolecular isomers which will produce ‘spikes’ in the detection spectrum window of ‘organics’, due to the isomer diversity alone .. and this has absolutely nothing to do with ‘life chemistry’.

    McKay’s ‘prediction’ is completely moot .. its not even worthy of being stated .. let alone the paper its written on!
    Last edited by Selfsim; 2019-Jul-07 at 08:58 AM. Reason: Corrected attribution

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    Quote Originally Posted by Selfsim View Post
    Originally Posted by Colin Robinson (on behalf of McKay)
    The first nine words of your message already contain a quite serious misrepresentation.

    My postings here are on no-one's “behalf” except my own.

    Do you understand that, Selfsim?
    Last edited by Colin Robinson; 2019-Jul-07 at 08:39 AM.

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    Quote Originally Posted by Colin Robinson View Post
    The first nine words of your message already contain a quite serious misrepresentation.

    My postings here are on no-one's “behalf” except my own.

    Do you understand that, Selfsim?
    Ok then .. I was merely trying to give the benefit of the doubt .. I asked previously whether or not the wording in these 'predictions' was yours or McKays .. You left that ambiguous .. so I was unsure .. If you like, I shall correct it.

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    Quote Originally Posted by Selfsim View Post
    Ok then .. I was merely trying to give the benefit of the doubt .. I asked previously whether or not the wording in these 'predictions' was yours or McKays .. You left that ambiguous .. so I was unsure .. If you like, I shall correct it.
    Thank you for correcting the "on behalf" bit. You can check exactly how McKay worded his predictions by following the link I provided in the opening post, that goes to his paper.
    Quote Originally Posted by Selfsim View Post
    ...

    This is such a dumb ‘prediction’, its hard to know where to start.

    A sample taken from Titan’s surface tholins is already expected to contain, (for eg), amino acids. Determining the presence of such molecules firstly requires classifying by molecular weight (using a mass spectrometer), but this is by no means sufficient for determining whether or not such molecules are actually biomolecules. Tholins are already known to contain many different structural isomers for a given mass molecule, so determining the isomers is vital before concluding biologically relevant content (biomolecules).

    So, any measure of McKay’s ‘relative abundance of different organics’ in a Titan sample, is already expected to include a wide variety of non biomolecular isomers which will produce ‘spikes’ in the detection spectrum window of ‘organics’, due to the isomer diversity alone .. and this has absolutely nothing to do with ‘life chemistry’.

    McKay’s ‘prediction’ is completely moot .. its not even worthy of being stated .. let alone the paper its written on!
    I don't think you understand McKay's point. Perhaps because my summary was too brief and sketchy...

    He says: " a biological distribution of molecules would be a series of relatively sharp spikes while an abiotic distribution would be smooth." Note that he doesn't just say "spikes", he says "relatively sharp spikes". By "relatively" he means: in comparison to an abiotic distribution.

    You mention the diversity of molecules produced on Titan by abiotic processes. That diversity would indeed mean lots of little spikes, but the broad outline would still be smooth. If McKay's hypothesis is correct, a series of relatively sharp spikes, corresponding to molecules favoured by Titan biology, would be present if there are biological processes happening, even if there were abiotic processes happening as well.

    The molecules showing up as relatively sharp spikes would not necessarily be those which are biologically significant on Earth, such as amino acids and lipids. They would be molecules which in Titan conditions have biologically useful properties such as functioning as catalysts (as amino acid polymers do in Earth conditions) or forming membranes (as lipids do in Earth conditions).
    Last edited by Colin Robinson; 2019-Jul-07 at 01:02 PM.

  31. 2019-Jul-07, 11:02 AM

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