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Thread: Mars' Methane - Martian Microbes?

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    Mars' Methane - Martian Microbes?

    Life on Mars? Scientists close to solving mystery of the red planet:
    Mission to find source of methane detected in atmosphere may have an answer in months, researchers believe
    ...
    In the next few months they hope to determine whether tantalising whiffs of the gas that have been detected on the red planet in recent years are geological in origin – or are produced by living organisms.
    ...
    Scientists expect it will take more than a year to complete a full survey of the planet’s methane hotspots but are hopeful that within a month or two they will have a good idea if its source is biological or geological in origin.
    ...
    “If we find traces of methane that are mixed with more complex organic molecules, it will be a strong sign that methane on Mars has a biological source and that it is being produced – or was once produced – by living organisms,” said Mark McCaughrean, senior adviser for science and exploration at the European Space Agency. “However, if we find it is mixed with gases such as sulphur dioxide, that will suggest its source is geological, not biological. In addition, methane made biologically tends to contain lighter isotopes of the element carbon than methane that is made geologically.”
    ...
    “We will look at sunlight as it passes through the Martian atmosphere and study how it is absorbed by methane molecules there,” said Håkan Svedhem, the orbiter’s project scientist. “We should be able to detect the presence of the gas to an accuracy of one molecule in every 10 billion molecules.”

    If the methane is found to be biological in origin, two scenarios will have to be considered: either long-extinct microbes, which disappeared millions of years ago, have left the methane to seep slowly to the surface – or some very resistant methane-producing organisms still survive underground. “Life could still be clinging on under the Martian surface,” said Svedhem.
    Noteworthy is that methane was first detected in 2004. 14 years later, and several on-surface laboratories, evidently still hasn't resolved the matter as far as ESA is concerned ...

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    I had read that the methane detected on Mars was a seasonal occurrence where levels spiked during the Martian summer. I suppose that both the bio v geo source debate could be connected to warming either way but I'd lean towards bio.

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    Methane detection has always been regarded as being a pretty poor so-called 'bio-indicator' (except on Earth .. where other lines of evidence are blatant).

    Whilst the press release speaks of what scenarios might emerge if a bio-positive origin is deduced, what of the bio-negative scenarios?
    One then has to wonder what is the value in planning to send even more rovers, given the amount of data already accumulated by orbiters, Earth based observations and the multiple onsite laboratories?

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    Quote Originally Posted by Selfsim View Post
    Methane detection has always been regarded as being a pretty poor so-called 'bio-indicator' (except on Earth .. where other lines of evidence are blatant).

    Whilst the press release speaks of what scenarios might emerge if a bio-positive origin is deduced, what of the bio-negative scenarios?
    One then has to wonder what is the value in planning to send even more rovers, given the amount of data already accumulated by orbiters, Earth based observations and the multiple onsite laboratories?
    I would suppose that as long as there is a possibility of terraforming Mars, there will be an interest in studying the planet. Even it is proved to be totally lifeless.

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    Quote Originally Posted by Superluminal View Post
    I would suppose that as long as there is a possibility of terraforming Mars, there will be an interest in studying the planet. Even it is proved to be totally lifeless.
    Then why keep reinforcing the 'martian life' story if/when there is zip physical evidence emerging for it from past and current missions? (We'll have to wait and see what happens with this methane pondering exercise first, but surely it makes sense to start working on the 'other goals' story now?)

    Just as support for the Apollo missions dwindled towards program end, I get the distinct impression the same is very likely to happen with 'search for martian microbe' expeditions. There are two more rovers scheduled in the next 2020 launch window. At least NASA's Mars 2020 Rover is openly more tailored to things other than searching for 'martian microbes'!

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    Quote Originally Posted by Selfsim View Post
    Then why keep reinforcing the 'martian life' story if/when there is zip physical evidence emerging for it from past and current missions? (We'll have to wait and see what happens with this methane pondering exercise first, but surely it makes sense to start working on the 'other goals' story now?)

    Just as support for the Apollo missions dwindled towards program end, I get the distinct impression the same is very likely to happen with 'search for martian microbe' expeditions. There are two more rovers scheduled in the next 2020 launch window. At least NASA's Mars 2020 Rover is openly more tailored to things other than searching for 'martian microbes'!
    How do prove Mars is and has always been totally lifeless? Absence of evidence is not evidence of absence. At some point, the search for life or fossils, will start to look like the search for Bigfoot. Interest in Mars will dry up.

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    The point is that when there has been no distinctive observations in the first place, then there isn't is any case to be 'proven'.

    At least Bigfoot left big footprints!

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    I don't know why you're all so negative about the likelihood of life on Mars.

    Billions of years ago it was quite Earth-like.

    The person leading the Viking life-finding experiments says the experiments did find life.

    Recent probes, intentionally, have been sent to areas which are least likely to support life.

    With this methane, there could be evidence of primitive life just about hanging on under the surface, perhaps in the caves which have been imaged.

    Scientifically, life on Mars is one of the very most important questions. The identification of independent-origin life would be a philosophical game-changer. It is well worth spending money on.

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    I don't know why you're all so negative about the likelihood of life on Mars.
    Don't forget, NASA has a rock from Mars in its possession and back in the 90's they claimed (and still do) that it contains fossilized evidence of past microbial life. Geochemists beg to differ. Here we have it in our hands, in a lab, and yet cannot come to a conclusion about it. Good luck getting a remote rover to make the final decision for us.

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    An interesting development, published just yesterday:

    Microbes living in a toxic volcanic lake could hold clues to life on Mars:

    Researchers at the University of Colorado Boulder have discovered microbes living in a toxic volcanic lake that may rank as one of the harshest environments on Earth. Their findings, published recently online, could guide scientists looking for signs of ancient life on Mars.
    ...
    To search for living organisms in this "fringe" environment, the researchers scanned samples of lake water for DNA. In research published this month in Astrobiology, they found the signature of one species of bacteria belonging to the genus Acidiphilium—a group of microbes that scientists have previously seen in toxic drainage from coal mines and other harsh locations.

    "It's not uncommon to find an environment with no life, say in a volcano that's self-sterilizing," Hynek said. "But to find a single type of organism and not a whole community of organisms is very, very rare in nature."

    If life did evolve on Mars, Hynek said, it would likely have survived in ways similar to the lake's bacterium—by processing the energy from iron- or sulfur-bearing minerals. Hynek has spent much of his career searching for places on Earth today that look like Mars did nearly four billion years ago, when liquid water was plentiful on the surface.

    It's a hard task: Rampant volcanism during that period created volatile and mineral-rich pools of water, giving rise to "Yellowstones all over Mars," Hynek said.
    In 2020, NASA is planning to send the Mars 2020 Rover to the Red Planet to hunt for fossil evidence of life. Hynek said that they should look first at these "Yellowstones."
    All interesting stuff, however the section I've emboldened above, I think, is a very interesting and a very unexpected comment to come from a scientist! In a resource constrained eco-system, the organisms most suited to that environment, will outcompete all others. So finding a single niche filling species should come as no real surprise!?

    Also, ESA's looking for sulfur free methane would seem to be at odds with the recommended environment from this particular study (ie: Hynek etal)?

    Ie, the ESA methane study focus is as follows (my emboldenment):
    “If we find traces of methane that are mixed with more complex organic molecules, it will be a strong sign that methane on Mars has a biological source and that it is being produced – or was once produced – by living organisms,” said Mark McCaughrean, senior adviser for science and exploration at the European Space Agency. “However, if we find it is mixed with gases such as sulphur dioxide, that will suggest its source is geological, not biological. In addition, methane made biologically tends to contain lighter isotopes of the element carbon than methane that is made geologically.”

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    My guess on where they are coming from is this:

    Sulphur dioxide production needs a source of oxygen for it to be an energy source for life. (In fact, you are more likely to get SO2 reduction to sulphides as an energy source on Mars.)

    Likewise, oxidising iron also needs oxygen availability.

    Oxidation doesn't look particularly viable on Mars because there's hardly any oxygen.

    Methane-producing bacteria use CO2 and hydrogen to make methane (CH4), and this reaction is their energy source. There is CO2 on Mars and there could be sources of geological hydrogen. So this looks more promising as a viable form of life on (more likely in) Mars.

    This methane won't be definitive proof one way or the other, I accept that. It will provide more weight to one side or the other, that is all.

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    Quote Originally Posted by kzb View Post
    ... This methane won't be definitive proof one way or the other, I accept that. It will provide more weight to one side or the other, that is all.
    And the point here, which I think needs to be made, is that proceeding with the science, does not benefit one iota from imagining there as being 'two sides' .. there are counterproductive drawbacks (ie: the 'Bigfoot' issue).

    With Mars, the hypothesis of: 'There may be methane producing martian microbes', can only really acquire 'weight' in the case of a bio-positive determination .. and not for the bio-negative. Its time to move on from that story unless some other solid observation presents (IMO).

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    Quote Originally Posted by Selfsim View Post
    And the point here, which I think needs to be made, is that proceeding with the science, does not benefit one iota from imagining there as being 'two sides' .. there are counterproductive drawbacks (ie: the 'Bigfoot' issue).

    With Mars, the hypothesis of: 'There may be methane producing martian microbes', can only really acquire 'weight' in the case of a bio-positive determination .. and not for the bio-negative. Its time to move on from that story unless some other solid observation presents (IMO).
    Well, the isotopic composition of the methane does provides weight in either direction. The methane may have a abiological isotope ratio, in which case it adds weight to the no-life scenario. This is important because the methane is the only pro-life evidence that the mainstream accepts as credible. I think.

    I do accept that the methane isotope ratio won't be the end of the story, and neither should it be. I have come round to the idea it would be more surprising if there wasn't life on Mars than the other way round.

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    Quote Originally Posted by kzb View Post
    Well, the isotopic composition of the methane does provides weight in either direction.
    .. or does it just lead to more questions?
    Carbon isotopic content is not always indicative of biogenic origin .. even for Earth specimens!

    Quote Originally Posted by kzb
    The methane may have a abiological isotope ratio, in which case it adds weight to the no-life scenario. This is important because the methane is the only pro-life evidence that the mainstream accepts as credible. I think.
    Some years ago now, (IIRC), isotopic carbon analysis of specimens taken from the Baja Peninsula did not return definitive biogenic origins even though cyanobacteria was evident from other testing.
    Its even trickier on Mars because C12/C13 ratios are different from Earth's also.

    Quote Originally Posted by kzb
    I do accept that the methane isotope ratio won't be the end of the story, and neither should it be. I have come round to the idea it would be more surprising if there wasn't life on Mars than the other way round.
    Then feel free to experience the surprise ahead of schedule!
    I personally find it difficult to envisage that such a conclusion can or will ever be concluded because of the entrenced beliefs about the existence of martian life. (And I think ESA has way more of these in the midst of their scientific community than NASA does).

    Eg: even the Curiosity MSL/SAM Prinicple Investigator (Paul Mahaffy) has shied away from dedicating SAM's TLS (Tunable Laser Spectrometer) time to investigating methane isotopes. This demonstrates the priority NASA has once assigned to the issue ..

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    Quote Originally Posted by Selfsim View Post

    Whilst the press release speaks of what scenarios might emerge if a bio-positive origin is deduced, what of the bio-negative scenarios?
    One then has to wonder what is the value in planning to send even more rovers, given the amount of data already accumulated by orbiters, Earth based observations and the multiple onsite laboratories?
    If there is/was life on Mars we wouldn't want to not know about its existence.

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    Quote Originally Posted by Paul Wally View Post
    If there is/was life on Mars we wouldn't want to not know about its existence.
    There are other ways which also achieve broader goals, if its not there, though .. (Eg: more focus on human onsite presence, and a build up of more extensive onsite lab-tools).

    I think ESA's announcements in the OP have also been leap-frogged, to an extent, by the recent NASA/Curiosity findings about seasonal methane variations .. At the end of the day, any orbiter derived methane analysis will probably call for more complex localised ground-based investigations involving the onsite presence of a human problem-solver(?)

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