Phosphine, Life, and Venus | Hacker News Reader

Phosphine, Life, and Venus

blogs.sciencemag.org

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Prof. Martyn Poliakoff on Periodic Videos has a great explanation of phosphine discovery and in general.

https://www.youtube.com/watch?v=NKWiOwt7eCo

Great video, thanks for sharing

Great video indeed and Professor Poliakoff's hair is simply stunning to boot.

tldw: Rats cannot vomit.

Horses can't either.

This story reminds me of the Viking lander biological experiments where NASA initially discovered carbon chemistry favorable to life on Mars. But it turned out, there were inorganic explanations to the observed data. In short, they had not done the preliminary work of understanding the inorganic chemistry of Mars. The recent life on Venus story reminds me of that Viking experiment in that our understanding of inorganic chemistry of the atmosphere of Venus is probably far from complete.

I agree. As much as I would like there to be microbial life in the atmosphere of Venus producing this excess phosphine, I suspect that there is some abiotic process happening that we don't understand as yet. Also, I didn't have "finding alien life" on my 2020 bingo card. :P

In any case, even if this should turn out to be a previously unknown, abiotic chemical process, it is still a significant discovery. It's just not time to run out and say "we found aliens!" yet.

Layperson, but my intuition is the same. Also, as far as I understand it, phosphine is seen on other planets (gas giants?). If phosphine is seen on these planets, is it really a stretch to think anything but similar explanations?

Is there a TLDR for why we understand that phosphine can be on other planets without life but not on Venus without life?

The temperature and pressure near the center of gas giants is crazy high. For Jupiter [0]:

> The temperature at the core boundary is estimated to be 36,000 K (35,700 °C; 64,300 °F) and the interior pressure is roughly 3,000–4,500 GPa.

It's similar to why you wouldn't be surprised to find diamonds deep underground in a mine, but if you found tiny diamonds forming in clouds that would be a major revelation.

[0]: https://en.wikipedia.org/wiki/Jupiter#Physical_characteristi...

As I understand it, the big deal about this discovery wasn't the presence of phosphine, but the amount of phosphine they found. The authors of the original paper went through all of the well-known scenarios for generating phosphine abiotically, and reasoned that the concentrations these would produce were too small for them to be the cause. That left either a biological mechanism (most likely microbial life in the atmosphere), or some unknown abiotic mechanism.

Edit: Fixed typo, phosphate -> phosphine.

To say "they had not done the preliminary work of understanding the inorganic chemistry of [Venus]" seems uncharitable, in this case. IIUC, the original paper is exactly an attempt to do that work, and the discussion in this blog post recognizes plenty of possibilities other than life.

Those Mars papers weren't necessarily any less rigorous. In context, I take "preliminary work of understanding the inorganic chemistry" to imply something like in situ sampling and analysis, which in some of the Mars cases revealed new geology, or at least hypotheses which were considered extremely unlikely given contemporary understanding--understanding that also included satellite imagery and other cutting edge remote sensing--were catapulted into hard fact shortly after the Exploration rovers landing. The paper covers its butt with qualifications like, "Even if confirmed, we emphasize that the detection of PH3 is not robust evidence for life, only for anomalous and unexplained chemistry." But the overall emphasis of the paper is rather optimistic, to say the least, very much like prior claims regarding Mars' chemistry and geology.

IMO, arguably we know far more about biological chemistry than we do about geology even on Earth. Even when we have a solid idea of the boundaries of what's geologically possible and impossible, we aren't nearly as knowledgable in terms of being able to order the possibilities in terms of relative likelihood. The Chicxulub impact and its effects were only confirmed within the lifetimes of most people on HN, for almost any reasonable value of confirmed--1990s, 2016 drilling, w'ever. We were already well along on our way to understanding the detailed chemistry of DNA before even the general concept of plate tectonics (let alone the finer details) became established scientific fact. Studies from the 2015 Mercury MESSENGER impact have overturned and are continuing to overturn established consensus on planetary geology. We should be skeptical of claims (implicit or explicit) regarding the relative likelihood of biologic vs non-biologic processes.

OTOH, perhaps governments aren't apt to fund those experiments without the enticement. Extravagant claims are useful to help make that happen, and either this group had that in mind or it's simply the case that we only ever hear about such studies when they do make extravagant claims. Either way, I would certainly support more Venusian missions even if my money is in history repeating itself--new geology, not new life.

The larger-scale lesson is that life has proved difficult to identify. We don't know all the inorganic paths to life-like signs. It will probably take a microscope to give definitive evidence, not chemistry.

The author says: "these things could mean that microbial life gets underway pretty readily" -- Or given that both Venus and Mars are close neighbours it could just mean that interplanetary debris from Earth seeded these places. I recall reading that this kind of debris is actually quite common.

I suspect we won't know until we can get samples back to earth to look at.

Might have started on Venus too.

Recent thinking is that Hot Venus is a relatively new phenomenon, possibly within the past billion years. Its previous incarnation would have been more hospitable to familiar forms of life.

https://zenodo.org/record/1253896

So assuming the phosphine is in fact indicative of life on Venus, there's a wide range of possibilities on where life started how many times and where it spread, but I think the most hilarious possibility would be if we realized we'd accidentally seeded Venus with extremophiles on one of our early probes.

(Which would basically be the least exciting option, although still kind of exciting WRT the possibility of terraforming.)

It would surprise me given the low chances that a) the particular bug that hitched a ride was capable of surviving 1. interplanetary space 2. the atmosphere of Venus and 3. happened to be one to produce phosphene (according to TFA we don't even know what that is yet); and b) reproduced so quickly and efficiently that within 40ish years was able to be detectable from earth...

Would be neat tho

Oh, extremely unlikely for a number of reasons. And neat if it happened as well.

But it would just be so, so disappointing compared to a second origin of life within the solar system or even compared to proof of some form of panspermia or natural seeding of life from planet to planet that it would be a lovely delayed "fuck you" from 2020 if we spend the next 20 years confirming the existence of microbes on Venus, retrieving samples, and finally sciencing enough to realize, goddammit, this is just recent Earth bacteria adapted to a novel environment.

This seems unlikely. We don't have many, if any, extremophiles which could actually deal well with Venus (extremophiles are normally a product of extreme environments on earth, and, if nothing else, we don't really have anything as acidic as Venus) and even if we did, it hasn't been a long time for them to establish themselves.

Yeah, it would be extremely surprising if we had anything on Earth that would do the trick (the layer of clouds in question is fairly nice, warm but not hot and fairly normal pressure, except for being chock full of sulphuric acid, so things like volcanic vents at the ocean floor or other typical "extreme" Earth environments wouldn't be a good analog for it), and even more surprising if it were able to contaminate a space probe as opposed to being confined to some, well, extreme environment on Earth.

But with respect to time, I'm not sure that intuitively 40 years wouldn't be enough -- you're talking about an environment that is uniform, free from competition, and circulating rapidly (the wind circles Venus every 4 days). So the microbes would only need to adapt to ~one environment, not a gradient of conditions of varying temperatures, humidity, and illumination; any resources that were present would be up for grabs as opposed to already claimed by better-adapted organisms; and you wouldn't be spatially bound to slowly expand from a single spot at a snail's pace. It'd be one big petri dish under the right circumstances.

"There are small and variable amounts of phosphine in Earth’s atmosphere, and its origins have been the subject of much argument."

They mention this in their press release video. We only think phosphine on earth is from life.

I think step one would be to find the life on earth that creates phosphine.

From another HN thread last week:
https://en.wikipedia.org/wiki/Will-o%27-the-wisp#Natural_exp...

( https://news.ycombinator.com/item?id=24493306 )

Cryptozoology aside, we don't know that phosphine would have come from life.

We need to reproduce the current experiments that have suggested it's life and more importantly track down the organism, now it's become a big deal.

I think this is the exciting thing, even if it turns out to be some abiotic process on Venus, there's will need to be new studies leading to improved understanding of planet-scale chemistry, in addition to new studies of life here on Earth. All of which will help refine the search for potential biosignatures on other planets.

In the video linked by dghughes [0] above Professor Sir Martyn Poliakoff outlines the mechanism by which life produces phosphine: bacterial breakdown of plant DNA.

[0] https://news.ycombinator.com/item?id=24543575

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