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

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

    From astrobiology.com

    There is a big press release coming out tomorrow (Monday, 14 September) morning at the Royal Astronomical Society. They want you to know its big news. The press release has been issued in advance to some journalists under embargo - but not others (like us). We have not seen the press release. But according to several sources knowledgeable with the details of the announcement (who are not under embargo) phosphine has been discovered in the atmosphere of Venus. Its presence suggests - suggests - some strange chemistry going on since phosphine is something you'd only expect to see if life (as we know it) was involved.

    The presence of phosphine is seen by many astrobiologists as a "biosignature" i.e. an indicator of the possible presence of life. The detection was made by the Atacama (ALMA) array located in Chile and the James Clerk Maxwell telescope located in Hawaii. The research team includes members from the University of Manchester, the Massachusetts Institute of Technology, and Cardiff University. A paper will appear in the 14 September issue of Nature Astronomy.

    From what we're told the researchers have concluded that abiotic mechanisms (i.e. ones that do not involve life) that might produce phosphine cannot account for the large amount that they have detected. The phosphine has been detected in the region within the atmosphere of Venus that is considered by some to be potentially habitable.

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

    Here’s Reuter’s take on the announcement.

    https://reut.rs/2ZDFta9

    WASHINGTON (Reuters) - Scientists said on Monday they have detected in the harshly acidic clouds of Venus a gas called phosphine that indicates microbes may inhabit Earth’s inhospitable neighbor, a tantalizing sign of potential life beyond Earth.

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    To sum it up: phosphine isn't something made abiotically on Earth. It's highly unlikely that it is the result of photochemistry. Volcanoes could produce tiny traces of phosphine, but many orders of magnitudes less than observed. Lightning and meteorites would also fall short by a factor of millions as an explanation. Two possibilities: some completely unknown, exotic chemistry in the clouds of Venus, or life.

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    Article from Nature Astronomy:
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    A very nice explanatory piece by radio astronomer (and now infrequent BAUTer) Yvette Cendes.

    There is a lot of information and misinformation going around today about the discovery of phosphine on Venus and life putting it there, so I wrote this post for those interested in an astronomer’s summary of what is going on! (Note, this post was originally written for Reddit, so apologies if I missed some formatting details.)
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    And even xkcd is getting on the act:

    https://xkcd.com/2359/

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    Whether the reported phosphine discovery is confirmed or not, it’s time to get past the clichés about Venus as “hellish”, “Earth’s evil sister” etc. Time to accept Earth’s neighbour planet as she is, and make the effort to learn more about her.
    It’s true that Venus surface today is much too hot and dry for life as we know it, but about 50 kilometres above the surface there is a temperate zone — a level where temperature, pressure and moisture levels are entirely compatible with life.
    It’s also true that Venus is a lot of acidity, even in the temperate zone, but here on Earth we have microbes that thrive in conditions almost as acidic.
    The surface of Venus may have been cooler and wetter 4 billion years ago, when the Sun wasn’t as bright. Perhaps micro-organisms first appeared at the surface, gradually migrating upwards as the surface became dryer and the clouds became thicker.
    One difference between finding an interesting compound in the clouds of Venus and finding it on a exoplanet, is that we can send robot probes (e.g. balloons or blimps) to Venus, equipped with devices to inspect the clouds and learn more…

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    Quote Originally Posted by Colin Robinson View Post
    Whether the reported phosphine discovery is confirmed or not, it’s time to get past the clichés about Venus as “hellish”, “Earth’s evil sister” etc. Time to accept Earth’s neighbour planet as she is, and make the effort to learn more about her.
    I don't think it's so bad to have those cliches about Venus--it will keep casual tourists from going there and getting into an unfortunate situation. I am sure (or at least I hope) that the planetary scientists and funding agencies are aware that Venus does have that other environment. In fact, having the cliche allows science writers to start stories with "Venus is not the hell we think it is--there is a temperate zone, and now scientists are exploring it..."
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    Quote Originally Posted by Jens View Post
    I don't think it's so bad to have those cliches about Venus--it will keep casual tourists from going there and getting into an unfortunate situation. I am sure (or at least I hope) that the planetary scientists and funding agencies are aware that Venus does have that other environment.
    For several decades now, planetary scientists and agencies have given Venus vastly less attention than Mars and the outer moons. Which is odd considering that Venus is the closest planet to Earth.

    In fact, having the cliche allows science writers to start stories with "Venus is not the hell we think it is--there is a temperate zone, and now scientists are exploring it..."
    True. That may be the sort of language that gets us beyond the clichés.

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    Quote Originally Posted by Colin Robinson View Post
    For several decades now, planetary scientists and agencies have given Venus vastly less attention than Mars and the outer moons. Which is odd considering that Venus is the closest planet to Earth.
    I don't think that planetary scientists and the agencies that fund them have given Venus less attention than Mars and other bodies because of a cliche. I think they have done so because it is only recently that we've recognized the more temperate regions of Venus' atmosphere might be a life zone, that visiting Venus is very difficult (the Russians showed in the 80s how hard it is on landers, and the idea of floating probes in the atmosphere is a new idea), and because all of space exploration is underfunded and so a lot of seemingly less attractive targets are given lower priority.

    My understanding is that even before this that NASA and ESA had proposed numerous Venus missions (LINK). I suspect their priority will be raised, particularly if this work is confirmed by others.
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    Quote Originally Posted by Swift View Post
    I don't think that planetary scientists and the agencies that fund them have given Venus less attention than Mars and other bodies because of a cliche.
    I'm not saying it's only because of a cliché.

    I'd suggest, though, that the clichés expressed a general sense of profound disappointment, mingled with horror, after the first probe data came back from fly-bys and landers in the 1960s. Before then, no-one really knew what to expect, and surface water and macro life weren't excluded...

    I think they have done so because it is only recently that we've recognized the more temperate regions of Venus' atmosphere might be a life zone,
    Although the same Venera missions which provided on-the-spot data from the surface of Venus also sent back data from various levels of the atmosphere during their descent. And a handful of astrobiologists have been writing for decades about the possibility of life in the clouds.

    that visiting Venus is very difficult (the Russians showed in the 80s how hard it is on landers, and the idea of floating probes in the atmosphere is a new idea),
    I take your point about how hard it is on landers. But the idea of floating probes is hardly new. It was put into practice in 1985, when Vega 1 inserted a balloon into the atmosphere of Venus and it sent back data for about 2 days.

    and because all of space exploration is underfunded and so a lot of seemingly less attractive targets are given lower priority.

    My understanding is that even before this that NASA and ESA had proposed numerous Venus missions (LINK). I suspect their priority will be raised, particularly if this work is confirmed by others.
    I suspect the same.

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    Quote Originally Posted by Swift View Post
    Nice!
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    So either it's some unknown planetary process, which is entirely plausible, or it's life... not entirely implausible.

    All the stuff I've seen mentions the "oh, the upper atmosphere's not hellish" angle. True. But my angle is not where, but how did it evolve there?

    Venus was not always hellish. In its earlier days, it's thought to have had liquid water. Then a runaway greenhouse ran away with it. So life could very well have begun back then, either on its own, or with meteors supplying microbes from Earth. And as Venus changed, so the life would have done what life does and adapted to the new conditions in the only place left where it could.

    I don't think it'll be life. But I'm not ruling it out either.
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    Could the phosphine be a relic of ancient life that died out billions of years ago? Or does need to be constantly replenished?

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    Quote Originally Posted by Superluminal View Post
    Could the phosphine be a relic of ancient life that died out billions of years ago? Or does need to be constantly replenished?
    The thinking is that it needs to be replenished. PH3 would trade Hydrogen for Oxygen very aggressively. We have it in our atmosphere in parts per Trillion and it doesn't last long.
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    Quote Originally Posted by antoniseb View Post
    The thinking is that it needs to be replenished. PH3 would trade Hydrogen for Oxygen very aggressively. We have it in our atmosphere in parts per Trillion and it doesn't last long.
    With concentrations in the ppt range on Earth and the activity of the molecule, the production may be by means not observed or though about on Earth to achieve concentrations of ppb.

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    While a sample return could give more information, it may too early to rule out the reverse process. An asteroid grazing Earths atmosphere scoops up atmosphere microbes and bounces back into space to later graze Venus and drop some microbes in a different atmosphere. A sort of upper atmosphere panspermia that goes not require an impact at either end.

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    Quote Originally Posted by Superluminal View Post
    Could the phosphine be a relic of ancient life that died out billions of years ago? Or does need to be constantly replenished?
    LINK
    ATMOSPHERIC FATE: Phosphine is a gas at ambient temperature(1). Gas-phase phosphine is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals and has a reported atmospheric half-life of 5 hours(2).
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    Quote Originally Posted by borman View Post
    While a sample return could give more information, it may too early to rule out the reverse process. An asteroid grazing Earths atmosphere scoops up atmosphere microbes and bounces back into space to later graze Venus and drop some microbes in a different atmosphere. A sort of upper atmosphere panspermia that goes not require an impact at either end.
    An Earth-grazer would be moving much too fast to scoop anything living and expect it to still be living. Its interaction with our atmosphere would be as hot as a re-entry.
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    Quote Originally Posted by Noclevername View Post
    So either it's some unknown planetary process, which is entirely plausible,
    An unknown planetary process is not impossible. But why were they looking for signs of phosphine? Wasn't it part of a broader project, aimed at eventually looking for phosphine traces in atmospheres of exoplanets? Wasn't it the working assumption of that project that non-biological production of phosphine on a rocky planet is very unlikely, so finding it on a rocky exoplanet will mean life on said planet is likely?

    If it does turn out that Venus is producing PH3 by means of non-biological process, that will be useful information for exoplanet researchers. It will mean identifying a life-bearing exoplanet will require a different strategy than trying to detect PH3...

    or it's life... not entirely implausible.

    All the stuff I've seen mentions the "oh, the upper atmosphere's not hellish" angle. True. But my angle is not where, but how did it evolve there?

    Venus was not always hellish. In its earlier days, it's thought to have had liquid water. Then a runaway greenhouse ran away with it. So life could very well have begun back then, either on its own, or with meteors supplying microbes from Earth. And as Venus changed, so the life would have done what life does and adapted to the new conditions in the only place left where it could.

    I don't think it'll be life. But I'm not ruling it out either.
    I think at this stage life is the most likely explanation. Unless and until someone can come up with an alternative hypothesis more specific than "unknown planetary process".

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    Quote Originally Posted by Colin Robinson View Post

    I think at this stage life is the most likely explanation. Unless and until someone can come up with an alternative hypothesis more specific than "unknown planetary process".
    I'm hardly a research scientist! I have no idea what alternatives have been proposed by professionals, nor how to test them. Just because a post on a forum does not have a good hypothesis does not mean no one has come up with a good hypothesis.
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    My understanding is that any abiotic process making that much phosphine on Venus would likely be so exotic that it would almost be more interesting than life.
    Kinda like LGM-1 turned out to be the first neutron star discovered.
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    Quote Originally Posted by Noclevername View Post
    I'm hardly a research scientist! I have no idea what alternatives have been proposed by professionals, nor how to test them. Just because a post on a forum does not have a good hypothesis does not mean no one has come up with a good hypothesis.
    The research scientists who published the recent findings made an effort to find a plausible non-life hypothesis, but they couldn't come up with anything more specific than "unknown photochemistry or geochemistry". Looks like it's either a form of life as we know it, or else it is chemistry as we don't know it.

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    Quote Originally Posted by Colin Robinson View Post
    The research scientists who published the recent findings made an effort to find a plausible non-life hypothesis, but they couldn't come up with anything more specific than "unknown photochemistry or geochemistry". Looks like it's either a form of life as we know it, or else it is chemistry as we don't know it.
    How much research has there actually been about complex chemistry under native conditions on Venus?
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    Quote Originally Posted by Noclevername View Post
    How much research has there actually been about complex chemistry under native conditions on Venus?
    There does seem to be a body of knowledge in this field. The researchers mention that they considered "~75 relevant reactions under thousands of conditions encompassing any likely atmosphere, surface or subsurface properties (temperatures of 270–1,500 K, atmospheric and subsurface pressures of 0.25–10,000 bar, wide range of concentrations of reactants)." They found that "PH3 formation is not favoured".

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    OK, thanks.

    I guess I'm just hung up on that word "likely". So often in studying the real world(s) we get surprised by the things we thought unlikely. We're still getting that effect from Mars, and we've studied it twice as much as Venus.
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    Quote Originally Posted by Colin Robinson View Post
    The research scientists who published the recent findings made an effort to find a plausible non-life hypothesis, but they couldn't come up with anything more specific than "unknown photochemistry or geochemistry". Looks like it's either a form of life as we know it, or else it is chemistry as we don't know it.
    I think there are other possibilities, for example, it could be that the signal has been misidentified as phosphine, or the concentration has been miscalculated (which may mean that abiotic sources could explain it). Or abiotic sources may be more abundant than currently know.

    I can also imagine, given the conditions on Venus, that there is some unusual chemistry going on there.

    None of those thoughts fault the authors. They seem to have done an extraordinary job in exploring as many possibilities as they good. But even their own wording hedges their bets.

    Claims of extra-terrestrial life is extraordinary and requires extraordinary proof. Let's see what follow-up research finds.
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    Quote Originally Posted by Swift View Post
    I think there are other possibilities, for example, it could be that the signal has been misidentified as phosphine, or the concentration has been miscalculated (which may mean that abiotic sources could explain it). Or abiotic sources may be more abundant than currently know.

    I can also imagine, given the conditions on Venus, that there is some unusual chemistry going on there.

    None of those thoughts fault the authors. They seem to have done an extraordinary job in exploring as many possibilities as they good. But even their own wording hedges their bets.

    Claims of extra-terrestrial life is extraordinary and requires extraordinary proof. Let's see what follow-up research finds.
    Venus being so (comparatively) near, I expect we'll get answers a lot more quickly than in the case of (for instance) Titan. After all, a probe mission like Dragonfly takes 8 years to get to Titan, whereas a probe can get to Venus in 6 months.

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    Also... Whether or not the presence and quantity of phosphine is confirmed, whether or not it's produced by microbes...

    In any case, it shows that extraterrestrial life, even in the inner solar system, is far more of an open question than sometimes supposed.

    Absence of evidence is not evidence of absence, at least not when our knowledge of even the nearest other planets is still so incomplete.
    Last edited by Colin Robinson; 2020-Sep-16 at 10:19 PM.

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