Another hype down

Discussion in 'Astronomy, Exobiology, & Cosmology' started by timojin, Jul 7, 2017.

  1. timojin Valued Senior Member

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    Mars is toxic

    https://www.yahoo.com/finance/news/mars-even-more-toxic-life-230200630.html

    We haven't found life on Mars yet, but the discovery of organic molecules in the soil and atmosphere have left many hoping that it's just a matter of time before we do. However, recent experiments may have thrown some cold water on these dreams. Scientists have studied compounds within Martian soil and discovered that they are toxic when combined with Mars' UV rays.

    We've suspected that Mars was home to perchlorates since the Viking Lander missions four decades ago; the discovery was confirmed by more recent rovers. However, scientists were divided on what it could mean. Some have argued that the presence of perchlorates on Mars actually might increase the likelihood of finding life on the red planet. Not only do perchlorates lower the freezing point of liquid water, but these compounds could be used as an energy source for bacterial life. After all, one type of perchlorate, ammonium perchlorate, is currently used as solid rocket fuel.

    According to their published findings in the journal Scientific Reports, scientists took common Earth bacteria, mixed them with Martian perchlorates and then exposed them to UV rays similar to those on Mars. The results were definitive: Bacteria were wiped out twice as quickly when perchlorates were present. Upon adding in other components found in Martian soil, iron oxide and hydrogen peroxide, the results were even worse: Bacteria were killed 11 times faster than with just perchlorates. The paper states, "These data show that the combined effects of at least three components of the Martian surface, activated by surface photochemistry, render the present-day surface more uninhabitable than previously thought."

    There is one upside to this discovery, though. While it's unlikely at this point that we'll find life on the surface of Mars (underground is still a possibility), the results of this study alleviate concerns about Earth-based bacteria contaminating the surface of Mars. While we should continue to take care when sending anything into outer space, any microscopic Earth-based life that hitches a ride to Mars will likely be killed by Mars' toxic conditions.
     
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  3. Yazata Valued Senior Member

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    I think that there is a remote chance that bacteria, archaea or something similar (but perhaps quite different) might still survive deep beneath the surface in cracks and voids in Martian rocks. Life is found here on Earth in similar environments.

    But the more likely possibility regarding life on Mars is that simple life once existed on Mars long ago but no longer does.

    And if the degradation of the Mars environment was a slow and gradual change, any early hypothetical Mars bacterial analogues might conceivably have evolved to adapt to the changes. So they may be more UV resistant than Earth bacteria.
     
    Last edited: Jul 7, 2017
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  5. Yazata Valued Senior Member

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    I think that the phrase "common Earth bacteria" might reveal a defect in this paper. What they should have done is select known Earth bacteria that metabolize perclorates. They aren't common, but they indeed exist.

    Wikipedia thinks that there is a diverse set of some 40 kinds of recently discovered (since the 1990's) Earth bacteria that are known to do this. They possess enzymes that reduce perclorate to chloride through several steps, producing energy, water and oxygen in the process.

    https://www.hou.usra.edu/meetings/lpsc2016/pdf/2946.pdf

    The most amazing thing about bacteria is their tremendous biochemical diversity. No matter what hypothetical biochemical pathway can be imagined, there's probably a bacterium already out there making use of it.

    And interestingly, perchlorates are apparently a basic chemical feedstock for some kinds of rocket fuel.
     
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  7. billvon Valued Senior Member

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    Exactly. It would be like taking extremophiles from a deep-ocean volcanic vent, putting them on moist soil at 70F, and noting that they died. "The Earth is toxic!"
     
  8. Yazata Valued Senior Member

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    Endoliths are forms of life here on Earth, typically bacteria, that live in the cracks and tiny voids deep inside rocks. This "deep biosphere" habitat is very mysterious and little is known about the life that's found in it. Nobody knows the history of these microorganisms or how they got where they are found.

    They have been found as deep as 3 km down in Earth rock, but that doesn't seem to be their limit, only the depth of the mines or drilling that discovered them. The limiting factor seems to be temperature, and given the tolerance of thermophiles for heat, the theoretical limit might be 4 to 4.5 km.

    If endolithic life exists on Mars, and given the likelihood that Mars' subsurface temperatures are lower than Earth's, it's conceivable that they might be found even deeper beneath the Martian surface.

    That would effectively make the surface UV referred to in the OP a non-factor.

    A bigger factor might be the nature of the Martian rocks. Here on Earth, endolithic microbial life is typically found in relatively unconsolidated sedimentary rock where voids exist among the rock grains. If Mars once had oceans and running surface water, do sedimentary rocks exist there?

    But apparently Earth endolithic life isn't always restricted to sedimentary rock, and is found in igneous and metamorphic rock too. (Research is underway investigating this.) Microorganisms might be able to grow their own voids by dissolving rock around themselves, burrowing in so to speak over long periods of time. (On Mars, they might have had billions of years.)

    https://en.wikipedia.org/wiki/Endolith

    https://searocksblog.org/2015/09/23/what-are-microbes-2/
     
    Last edited: Jul 7, 2017
  9. DaveC426913 Valued Senior Member

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    In a dimly-lit lab under the frozen polar ice of Mars, a Martian scientist just published a paper showing that Martian bacteria, when exposed to the deadly oxygen and water atmosphere of Earth, die 20 times faster - showing that Earth is far less hospitable to life previously thought.
     
  10. Write4U Valued Senior Member

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    You must be joking.....

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    Think about what you just said. A dimly-lit lab under the frozen polar ice of Mars . What kind of ice are you talking about? Frozen water?

    Are you talking about anaerobic bacteria to which oxygen is deadly? Then the conclusion is ridiculous. And even if you could find life that does require oxygen, ice itself contains oxygen, it's frozen water !

    If indeed life exists on Mars that is a tremendous discovery, but as far as the conclusion that therefore Mars provides a more hospitable environment that the earth, makes it a candidate for the trash-can, IMO.

    If you consider the enormous variety of life on earth and its chemical composition of the air we breathe which made this richness of fauna and flora possible v the variety of anaerobic life forms that might exist on Mars, you can readily see that the earth's troposphere is much, much more conducive to life than the (near) airless troposphere of Mars.

    But here on earth we also have anaerobic organisms and extremophiles, which can live in environments that are deadly to all other life on earth. Life around Black Smoker is deadly to surface life and vice versa. So are ice worms which exist in our poles. Water Bears can remain alive for years without water. Those are the left-overs from when the earth's atmosphere was still forming and living organisms managed to find niches where they can exist. The earth is a Cindarella planet, make no mistake about that, and any proposition that we should start building cities on Mars, because it is a more hospitable planet the earth as has been proposed by some demented minds, is just plain madness.

    Check out the Robert Hazen lecture on how life began as probabilistic combinations of chemicals. (start viewing at 25:10)

    p.s. The Carnegie Institute of sciences is now doing deep-earth research for signs of bio-molecules and possible life forms.

    If anything, the existence of anaerobic organisms on Mars proves that life can exist, regardless of environment, but the claim that, a few species of living organisms can withstand the conditions of the Martian environment logically leads to the conclusion that Mars is more amenable to life than the earth, is utterly ridiculous .

    However it would do away with the notion that Earth is the only planet that can support life and that life may well be abundant throughout the universe. Bye, bye, Creationism as revealed in Scripture..
     
    Last edited: Jul 8, 2017
  11. DaveC426913 Valued Senior Member

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    Seriously? You can't get your head around the idea that "our bacteria cannot survive on their planet" is biased toward which planet you're on?
     
  12. Write4U Valued Senior Member

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    My objection is to this statement you made
    Well yes, maybe for those organisms which exist on Mars. Perhaps Mars organisms might thrive in some areas on Earth, perhaps not.

    And conversely, most Earth organisms would die on Mars. But how would you know? What proof do you have ?
    We know Earth also harbors some anaerobic extremophiles that can withstand incredibly harsh conditions and can even survive in pure space for a period of time. They might do very well on Mars.

    We don't know either way, but we can test both ways once we get to Mars and test some of Earth's extremophiles in that environment and bring back samples from Mars and test them in certain areas on Earth that resemble the conditions on Mars.

    But you cannot seriously suggest that Mars offers a more hospitable ecological environment than Earth. Do you believe it likely we'll find that Mars is teeming with millions of species of incredible variety, such as on Earth? Do you believe Mars has a more "balanced chemical menu" than Earth (as Hazen suggested in his lecture)?

    I understand the thrust of your statement, but the way you stated it is the opposite of what you were trying to say, IMO.
     
    Last edited: Jul 9, 2017
  13. Write4U Valued Senior Member

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    That must be an ironic statement..

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    Take a fish out of water and it dies, what is so remarkable about that?
    And as to your example, here is another.

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    Thermophiles, a type of extremophile, produce some of the bright colors of Grand Prismatic Spring, Yellowstone National Park
    https://en.wikipedia.org/wiki/Extremophile
     
    Last edited: Jul 9, 2017
  14. Write4U Valued Senior Member

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    As I understand the word extremophile, it is not that that they have evolved in extreme environments, but that they are adaptable to extreme environments, .....difference!
     
  15. billvon Valued Senior Member

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    Nothing. Put a human 20 feet under water and keep him there, he also dies. That is not an argument that either Earth seas or Earth lands are "toxic."
    Nope. Extremophiles just live in extreme conditions, ones that would kill most other Earth life. They are not necessarily more (or less) adaptable than any other organisms.
     
  16. DaveC426913 Valued Senior Member

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    I think you should re-read my post 6. I think you just scanned it and misinterpreted it.

    They're Martian scientists in a Martian lab. Thus, their default about "life" is a Martian bias.
     
  17. Yazata Valued Senior Member

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    4,659
    Everybody seems to agree, but that agreement is being expressed confrontationally.

    Bacillus subtilis bacteria from Earth were observed to cease being viable fairly quickly then exposed to magnesium perchlorate and UV radiation in various test setups. The paper mentions the bacteria tested being in a 'vegetative state' but it isn't clear to me if that means endospores (which are highly resistant to environmental conditions).

    My objection up in post #3 was that they probably shouldn't have used Bacillus subtilis but rather some bacterium that possesses the necessary enzymes to metabolize perchlorates. Presumably perchlorate toxicity wouldn't be an issue for bacteria that feed on perchlorates. And I also mentioned endolithic bacteria that live inside rock to eliminate the effects of UV radiation (as well as minimize temperature extremes, dryness and so on).

    So I'm inclined to think that the research in the OP does demonstrate that Mars surface conditions in direct sunlight in particularly perchlorate rich areas might be hostile for Bacillus subtilis. But that doesn't mean that Mars is hostile for all life, particularly for hypothetical bacterial analogues that evolved there and occupy hospitable ecological niches.

    Mars may have ceased having liquid oceans and running water, and turned into a cold almost airless desert very slowly. If that's the case, then any life that may hypothetically have arisen there in the planet's early days would have had billions of years to evolve to adapt to the new conditions. That means becoming what Earth microbiologists would think of as extremophiles. (Since on Mars, extreme is pretty much all you have these days.)
     
    Last edited: Jul 9, 2017
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  18. Write4U Valued Senior Member

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    That was my first thought visualization. Note that my response was that you had to be joking.
    http://www.bioxplorer.com/extremophile-bacteria/

    Ice on Mars is not the same as ice on earth? I know, I know there are planets with frozen methane, etc.
    But then methane can also be found on earth and in fact is caused from bacterial excretia.
    https://www.khanacademy.org/partner...ife/mars-modern-exploration/v/martian-methane

    And in a later post I explained that if an organism can survive on Mars it, might well be able to thrive on earth. Is that not the foundation of the concept Panspermia ? Are you rejecting this possibility out of hand?

    I also addressed the possibility, that certain extremophiles which we know exist on earth and have been tested in space, might well be able to survive the Martian environment. That is why they are called extremophiles as per wiki.

    The point is that extremophiles are so simple in structure, they can use almost any available resource to their advantage. And as Hazen explains, UV in deep space may well be causal to forming bio-molecules.
    Why did we take extraordinary steps to ensure sterility inside our capsule when we visited the moon. Is to avoid bacterial contamination ? Why else should we have to bother with such a cumbersome process?
     

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  19. Write4U Valued Senior Member

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    Take your pick,
    I think the misunderstanding is the assumption that all extremophiles are complex structures, rather than pure strands of bio-chemical compounds, able to duplicate themselves, and able to use other available compatible chemicals. This ability would be difficult for more complex living organisms with fixed DNA structures, which require a specific environment for them to be able to use specific sources of energy.
    https://en.wikipedia.org/wiki/Extremophile

    We keep trying to view the universe as a collection of separate things, but the reality is that we are all part of the whole and everything shares many parts of the whole.

    I do agree that for Humans to find a hospitable planet, it has to have a very specific ecological environment. But certain extremophile organisms are perhaps more virus-like than actual living organisms and able to convert (morph) from one state into another state.
     
  20. DaveC426913 Valued Senior Member

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    Tongue-in-cheek is more like it.
    Changing perspective to a hypothetical Martian viewpoint sheds light on our Earth-centric biases.
     
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  21. Write4U Valued Senior Member

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    That seems a reasonable assumption, but then I just ran across this lecture by Robert Hazen about the existence of carbon based bio-chemicals and possible microbial life in extreme environments, both on Earth and on Mars.
    A fairly new science of carbon based bio-molecules at extreme depths, temperatures, and pressures.
    It is a fascination presentation of otherwise completely unknown bio-chemistry.
     
    Last edited: Jul 11, 2017

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