The big announcement about supposedly biogenic chemicals on Venus: 11 a.m. Eastern time, 4 pm BST (watch here)

September 14, 2020 • 9:00 am

I’ve written a few times since yesterday about the Big Astronomy Reveal today. It’s going to be the subject of a live announcement from the Royal Astronomical Society in about an hour from this posting: at 11 a.m. Eastern time (US) and 4 p.m. BST.

As I suspected, It’s going to report the discovery of phosphine (PH3) in the atmosphere of Venus—presumably from the light spectrum—and since the compound is made on Earth only by organisms, this is said to be “evidence for life”. I am dubious, for, as J.B.S. Haldene said, nature is queerer than we can suppose.  It would be arrogant to claim that we have exhausted all knowledge about how phosphine is produced.

There will of course be tons of speculation about life elsewhere in the Solar System, and that would be cool if it were true. We’ll just have to wait and see. At any rate, tune in here in one hour from this posting.

76 thoughts on “The big announcement about supposedly biogenic chemicals on Venus: 11 a.m. Eastern time, 4 pm BST (watch here)

    1. In the context of an atmosphere rich in oxygen, with organisms whose biochemistry depends on organic phosphates … yeah it is flammable and toxic.
      Outside those contexts, that isn’t necessarily so.

  1. “the compound is made on Earth only by organisms”


    The other famous phrase that is important in these moments:

    “Life *as we know it*”

    Still – interesting!

    1. Phosphine is produced everywhere from starts to planets of the thermodynamic conditions allow, normally > 800 K and 0.1 atmosphere pressures. (Venus has local spots, likely active volcanoes, that get that hot.)

      1. Thanks for clearing that up.

        Then there’s relative rates – enzymes make things happen in comfortable conditions within our lifetimes, though I know of no enzymes with phosphine products.

  2. According to Wikipedia, phosphine is made on earth by an abiotic means, albeit a non-natural industrial process.

    “ Industrially it can be made by the reaction of white phosphorus with sodium or potassium hydroxide, producing potassium or sodium hypophosphite as a by-product.

    3 KOH + P4 + 3 H2O → 3 KH2PO2 + PH3
    Alternatively the acid-catalyzed disproportioning of white phosphorus yields phosphoric acid and phosphine.”

    However, it requires high temperatures, above 200 degrees C, which are not common naturally on earth (except geothermal), but everywhere on Venus. It will take some work to rule out an abiotic process. We’ll see if they’ve done that.

    1. Seriously, there are so many possibilities for interesting chemical reactions on Venus, given the temperatures, pressures, and chemistry available. Life would be WAY down on my differential diagnosis list.

      1. Venerochemistry is likely to become a more important subject of research then it is currently, and become it’s own field within the planetary sciences, distinct from geochemistry.

    2. I’m listening now. They’ve ruled out a bunch of the more obvious pathways (photosynthesis, lightning, meteorites), they’ve ruled out surface production, and they’ve identified that it occurs fairly high up in the cloud layer where the temperature is lower than that.

      They’re being pretty conservative and they’re basically calling for more probes to go and Mass Spec the atmosphere to fully characterize the gas components. They’re basically saying that if it’s abiotic, it’s still very interesting because it would be an unknown process.

      1. It is well above my pay grade. I look forward to scientific back-and-forth to follow. Definitely worth another mission to the Venusian atmosphere. We’ve actually sent more probes to Venus than Mars, but if they land they do not last long.

      2. That seems reasonable. I would like to see a sampling mission lower by parachute into the atmosphere, maybe with cruise ability to linger for a time while it filter feeds for samples of airborne stuff, and then blast out of there for a return trip to earth.

        1. Their ideal mission would be a balloon-mounted instrument, so it can hang at a specific altitude/atmospheric layer.

          Just going on what they said in the Q&A, it seems we’ve done that before, but with Venus’ corrosive atmosphere the balloons only lasted a couple hours. That was decades ago though, so hopefully we can come up with better tech that will last days or weeks.

    3. I left extensive comments of the first thread, where a paper with Sara Seager among the luminaries looked at phosphine as biosignature. They found that planets with temperature > 800 K and pressures > 0.1 bar (both of which Venus fulfill locally on presumed volcanic spots) produce abiotic confounds.

      Else phosphine is seen in stars to terrestrial planets.

  3. The underlying unstated and unsupported premise is that — given a planet with at least a little bit of water — life will easily, quickly, and almost inevitably evolve. It is a philosophical, i.e. feel good, position I don’t buy.

    1. They are not making that premise, as (AIUI) there is no water in the atmosphere of Venus. So if it’s a bug, it would need to be unlike Earth life in not needing water (or it would have to produce it itself inside some protective coating).

    1. I suspect that might be because humans have long held the notion that maybe Venus, the planet most Earth-like in size and in (superficial) appearance, might have life…though the more we learned about the planet, the less likely that seemed. Venus is also just nearer and less “alien” in character than Saturn. But if it’s atmospheric organisms that are being speculated about, I don’t see why Saturn would actually be less likely a locale (or more likely).

      1. And, technically, Venus is in the habitable zone of the solar system. Which goes to show that a planet in the habitable zone may not be all that habitable.

        FWIW, I think the most likely place to discover life in our solar system may be outside the habitable zone, the moons of Jupiter and Saturn.

        1. To me, one of the most exciting discoveries of the outer planet probes is that the habitable zone may well be more extensive than previously thought.

          Early models were based on the zone where stellar radiation provided sufficient energy to result in liquid water.

          The outer planet probes, however, demonstrated that there are other energy sources that provide the same result. The massive tidal forces of the gas giants on satellites like Europa or Enceladus appear to provide the necessary energy despite their distance for our sun.

    2. Venus is not Jupiter. I don’t mean to be facetious, but that’s the reason. The conditions on Jupiter are such that phosphine can form and was expected. On Venus the conditions are different and the levels they’ve detected can’t be explained by any known abiotic processes going on on Venus.

      Of course we don’t know what we don’t know, so I’m not convinced of life there.

      I watched most of the conference – they did NOT claim they found life but what they did find is very interesting and quite possibly is life. We need to send a probe there.

      1. At the end of the Q&A they mentioned that they’re in discussions with Rocket Lab and have been offered a 3kg payload – now they need to agree on the instruments to send!

    3. They covered gas giant production. Evidently (a) we know the processes that produce it around the gas giants, and (b) those processes can’t be happening in Venus’ atmosphere because they require hundreds or thousands of atmospheres of pressure of hydrogen gas, and Venus is lacking in both the gas itself and the pressure needed for the reaction (maximum pressure is at the surface and is roughly 93 Earth atmospheres).

      It seems to me that they’ve done a lot of homework on alternative explanations, so that whether the source is life or not, the process is going to end up being something pretty novel/unexpected.

      1. The gas giants lack oxygen. Venus has atmospheric oxygen (carbon dioxide) which destroys phosphine and blocks phosphine from being created abiotically.

        1. That Venus’ atmosphere is composed primarily of a molecule that contains oxygen is irrelevant to the phosphine question.
          The significant difference between the gas giants and Venus’ atmosphere is that the gas giant atmospheres are quite strongly reducing – under which phosphine is relatively stable, like it’s nitrogen analogue, ammonia ; however the Venusian atmosphere is fairly oxidising (sulphuric acid is a moderately strong oxidising agent, in addition to being a strong acid), which would make destruction rates for phosphine a lot higher. (It would also increase the destruction rate for ammonia.)

    4. Wow. This seems instantly disqualifying to the hypothesis that Venusian phosphine might have been made by a living organism. That’s by far the least likely explanation.

    5. I didn’t know that phosphine was found on our own gas giants, but generally it is seen from star to planet atmospheres given enough heat.

      The case of Venus habitability is an old one. If Venus had an early ocean, and in modern 3D models it could still have one so the question of its loss becomes problematic, life could get started.

      The atmosphere layers that have the same temperature and pressure as Earth surface is where an EM absorber was found early on. Modeling it results in a preference for cell sized particles, and no one know what it is.

      The problem seems to be that the layer is ~80 % sulphuric acid, and Earth life can stand < 5 %. The opportunity is that the phosphine production rates seems to be 5 order of magnitudes larger than known abiotic processes can produce, but 1 order of magnitude less than then life can produce on Earth [ ].

  4. Well I left at the questions. Emphatically NOT a claim to have found life, rather possible signs thereof. Really a plea for more funding & further research especially space missions. I doubt we will then get any confirmation or clarification for some years. Those of us who are older will be impatient to know more asap!

    1. That’s the hope!

      IMO their research does a pretty good job of selling the value of more missions. Whether it’s life or not, their findings seem to me to make a good case for looking more closely into what’s causing it.

    2. Shouldn’t there be other chemical traces consistent with life?

      We could only possibly answer the question for “life similar to the life we find on Earth”.

      We have one biochemistry and so one data point.

      For an example of other plausible biochemistries I like to bring up the pressure-temperature conditions under which liquid ammonia, liquid water and liquid carbon dioxide are simultaneously stable. The chemistry isn’t wildly incompatible with a carbon-based biochemistry similar to ours, but the typical temperatures would be in the 230-250 K range. And every reaction involving solvation of a compound (e.g., all protein folding) would be considerably different with three solvating molecules to play with, all with different sizes, shapes and electron distributions. But .. below water’s freezing point ,so discard it from consideration.
      Personally, I find the fact that the atoms of life are the commonest atoms in the universe (bar helium). (There are other atoms essential to human life, but that’s not the point at issue.)

      1. What do you suppose the chances are of a DNA based genetic code developing independently? Either on early Venus, or elsewhere in the Universe?

        1. Interesting question. If we discover life based on DNA within in our solar system, I would assume a common origin. If we somehow discovered life based on DNA outside our solar system, I don’t know what I’d think. Perhaps panspermia. I cannot see why DNA should evolve inevitably.

        2. It’s not impossible, but there are a considerable number of details which there is no obvious (e.g. thermodynamic) reason for having “chosen” (e.g., the particular set of bases used to provide the digital encoding of genetic information) that finding a putative “second genesis” which matched all those details would get very suspicious,suggesting contamination, one way or the other, between planets.
          If, for an example, we found a genetic system with A, T, U and A.N.Other.Pyrimidine then that would be fairly strong evidence of an origin separate from ours (at least, since the terrestrial system stabilised on AGCT/ AGCU combination).
          Then there is always the minefield of choosing stereochemistry. There the thermodynamic barriers at choosing a system are quite low, but the barriers to changing systems rapidly get quite high.
          Another aspect that I saw some interesting work on a few years back was the encoding system between genetic and protein-synthesis systems. The current look-up table between DNA/ RNA triplet and resultant amino acid in the protein …
          [sorry, lost my train of thought. D*g-satting for the neighbours – d*g required sat.]
          … Yeah, that look up table is fairly stable in it’s core, but it isn’t precisely clear why it happened that way, when a multiple of other ways can be chosen to map 20-odd amino acids onto 64 possible codons. Something like (64!/(20!*44!)) (about 10^16, for numbers about “20-odd”). The odds of two unrelated systems making exactly the same choices are small.
          In short, I’m fairly sure that demonstrating a difference between a terrestrial biochemistry and a Genesis 2.0 biochemistry would be fairly simple (it might not even require sample return), proving that the two systems are related would be considerably harder, and probably would require sample-return. So, on probability, one would most likely have to engineer a sample-return system, but with the possibility that it would be overkill to answering the question. But equipment and procedures for sample return are going to be needed eventually, so it’s not exactly wasted effort.

          1. Interesting topic. Since there is nothing completely definite about how to configure DNA life, it would likely be somewhat different elsewhere. Makes sense.

  5. I’m old enough to remember the hullabaloo when one of the biochemistry experiments on board the 1976 Viking landers mixed Martian soil with a “soup” of radiatively-labelled organic nutrient molecules, and carbon dioxide was released. Life on Mars! Except that it was actually a non-biological reaction produced by superoxide compounds in the Martian soil.

    So phosphine in the atmosphere of Venus is an interesting discovery, but since the authors of the paper invoked Carl Sagan, we should remember his dictum that extraordinary claims require extraordinary proof.

      1. Not in the research paper, perhaps, but they were counting on the media to pick up on the “life on Venus” angle, and judging from the headlines, they succeeded:

        BBC – Is there life floating in the clouds of Venus?

        The Independent – Possible signs of alien life discovered on Venus.

        CNN – Gas found on Earth that signifies life has been detected in clouds on Venus.

        1. “BBC – Is there life floating in the clouds of Venus?

          The Independent – Possible signs of alien life discovered on Venus.

          CNN – Gas found on Earth that signifies life has been detected in clouds on Venus.”

          They can’t help themselves, apparently.

      2. I could hear the fury of journalists denied their purple headlines from here. Unless … they chose to discuss things which the scientists didn’t claim, then drum up some eyeball-seconds and clicks from that.

  6. The live announcement was interesting – they seem to have covered most contingencies from my (extremely ignorant) perspective, although of course they were careful to add caveats about exotic chemistry etc.

  7. If there does turn out to be life on Venus, will that put any dent in the popularity of creationism? Even though evidentially, it seems like a very small increment, psychologically it could be big.

    1. Nah. Given the massive evidence against creationism that already exists, why would Venusian microbes make a difference? I am curious how they would spin the discovery of ET intelligence, should that ever happen.

    2. God could shoot President Trump on Fifth Avenue during the ticker-tape memorial parade for the first Muskonauts on Mars, announcing in league-high letters of fire legible to anyone capable of reading Roman-era Greek longhand that none of it was true and he’d let evolution do all the hard work and he’d been in the pub for the last 13.8 billion years …
      and the YECs and OECs would remain at each other’s throats, united only in their demands for the resurrection of one the Hereditary Presidents.
      (Actually, whether resurrection or reincarnation would be better would probably lead to a schism or several as well.)

  8. The claims of the scientists involved appear to be modest and appropriately hedged. Venus appears to have been more hospital to life in the past so the speculation that there is still microbial life there now that consumes ultraviolet light, can handle the acidic and dry conditions, and manages to remain floating the atmosphere over millions of years, is within the realm of being plausible. Another plausible explanation is that it is not phosphine, future more thorough analysis of the light signature may be able to resolve that.

  9. Even if it isn’t life, it’s an entirely new chemical process that’s unknown to current science. This is an amazing discovery regardless of the end result.

      1. … and also the destruction rate of phosphine, by known processes, under those conditions, is higher than is compatible with the concentrations deduced from spectral modelling.

        There is a lot of logic from measuring radiation intensity at various wavelengths to getting a modelled concentration for that component. It is a mature science, but it is also complex. That’s one of the reasons they had to put a mass spectrometer onto Mars – to have a much simpler argument chain for the “is there methane on Mars?” question.

        I think they’re going to have to soft-land a balloon carrying a mass spec (or a gas chromatograph front-ending an MS detector/ characteriser end) into Venus’ atmosphere. Minor corollaries and prerequisites might include a VPS system (“GPS for V”) for tracking where the system is, extending the “interplanetary internet” to cover for when Venus is in Solar conjunction, or there is a solar storm at one end or the other of the link … less like years of work and more like decades.

        1. That’s pretty much what the scientists are asking be done.

          However IMO if we’re going to go all that way, and we suspect life, we’d better bring along some instruments that can detect and analyze huge (i.e. millions of atoms) structures too, not just GC/MS. Ideally some sort of sample return as well, though that might be a bit optimistic for an initial mission.

  10. Honolulu Star Advertiser front page (secondary) headline, over local reporter by-line: Sign of Life on Venus discovered with Hawaii Telescope (the James Clerk Maxwell radio telescope).
    Below: “could well point to extraterresrtial life”…

  11. The NY Times succumbs to speculation:

    “Life on Venus? Astronomers See a Signal in Its Clouds”

    “After much analysis, the scientists assert that something now alive is the only explanation for the chemical’s source.”

    Is that what the scientists asserted? I gathered otherwise from other posters here. (I haven’t seen the news conference.)

    [Sarah Stewart Johnson] added: “Venus has been ignored by NASA for so long. It’s really a shame.”

    She obviously needs to become NASA administrator. Thanks for your opinion and gratuitous dig at NASA.

    “Future missions to the planet are still mere concepts.”

    Fatuous reportorial bloviation.

    “Here on Earth, phosphine is found in our intestines, in the feces of badgers and penguins, and in some deep sea worms, as well as other biological environments associated with anaerobic organisms.”

    From the above, I guess, for the record, it’s also found in human (aerobic organism) feces. Apparently too uncouth a topic to mention it.

    ‘Dr. Sousa-Silva was surprised when Dr. Greaves said that she had detected phosphine.
    “That moment plays in my mind a lot, because I took a few minutes to consider what was happening,” she said.’ ” . . . she believed there could be no other obvious explanation than anaerobic life.”

    As any scientist no doubt should so consider. (Per Bill Nye the Science Guy: “Consider This”)

    ” . . . she [Sousa-Silva] believed there could be no other obvious explanation than anaerobic life.”

    Of course, what one BELIEVES is the basis of the scientific method.

    Enough of my logorrheic ranting.

    1. OK – I can summarize.

      Rats cannot vomit.

      Oh – sorry, that’s supposed to be saved til later.


      … I think everyone already got it – there’s no good mechanism to produce phosphine on Venus, while there are for – trigger warning- Jupiter and Saturn (I think Saturn). Phosphine is being replenished on Venus as the Sun’s radiation breaks it down. The Professor explains I t’d have to be something anaerobic floating in the atmosphere – but I’m not sure why it couldn’t be ground based. Professor emphasizes he knows enough to reserve conclusions for now.

      Best for last:

      Antimony compounds make H. sapiens vomit.

    2. Great lecture. In addition to the general info on phosphine, I learned that rats cannot vomit, which is why they eat poisoned food and die.

Leave a Reply