Phosphine in Venus's atmosphere: evidence of life or chemistry?

Peter Dow

Peter Dow

Registered Senior Member
The BBC and reputable news agencies like Reuters are hyping claims that the detection of phosphine in the atmosphere of Venus "could be" evidence of life on Venus.

Are they right or don't they know their chemistry?

P4(g) + 6H2O(g) + 6CO(g) → 4PH3(g) + 6CO2(g)
 
Peter Dow said:
The BBC and reputable news agencies like Reuters are hyping claims that the detection of phosphine in the atmosphere of Venus "could be" evidence of life on Venus.

Are they right or don't they know their chemistry?

P4(g) + 6H2O(g) + 6CO(g) → 4PH3(g) + 6CO2(g)
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Hmm, I'm not sure why the reaction you post would be relevant. What makes you think gaseous elemental phosphorus would be expected in the Venusian atmosphere?
 
Peter Dow said:
The BBC and reputable news agencies like Reuters are hyping claims that the detection of phosphine in the atmosphere of Venus "could be" evidence of life on Venus.

Are they right or don't they know their chemistry?

P4(g) + 6H2O(g) + 6CO(g) → 4PH3(g) + 6CO2(g)
Click to expand...
You do know that chemistry doesn’t work just because you can balance each side of the supposed reaction with equal numbers of each element? Care to explain under what conditions those molecules are supposed to interact to combine the carbon dioxide and phosphine? Why is the carbon monoxide needed, when phosphorous can react directly with water? And why not react directly with hydrogen?

But I’m sure you are going to explain all this, right?

As for hyping, sure, it’s how they make their money. But they are right, in that it could be produced biologically in the atmosphere of Venus. They have ruled out some of the more obvious means of producing the gas, but since they don’t know everything about Venus, there is always the option of a geophysical cause, or something else.
What they also don’t actually tell you, though, is that microbes aren’t yet proven to produce phosphine biologically. It is widely thought to be the breakdown of certain biomass that gives rise to it, not the biological activity of that biomass itself. But more testing in labs is needed.

But please, do explain your reaction and how you think it actually works. :)
 
The overall reaction looks plausible to me if we experimentally mix phosphorus with water and carbon monoxide at the pressure (92 bar) and temperature (464 °C) found at or near the surface of Venus.

If experimentally some phosphine is produced in such conditions then such a finding would suggest the reaction is likely to be more relevant to what's happening on Venus than wild theories of "life on Venus".

Water and carbon monoxide are present in the atmosphere of Venus
There's no hydrogen or oxygen in the atmosphere of Venus so I've not suggested those as initial reactants or final products.

Elemental phosphorus on the surface of Venus I have no evidence for, admittedly, so the phosphorus for my reaction may be sourced from some other precursor phosphorus compound or phosphorus-rich mineral.
 
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A key component to this mystery is not simply that phosphine is found - but that it is found in a significant concentration suggesting it's being continually produced - as Venus' atmo is going to break it down almost as soon as its produced. So what''s producing it in such quantities?
 
Peter Dow said:
The overall reaction looks plausible to me if we experimentally mix phosphorus with water and carbon monoxide at the pressure (92 bar) and temperature (464 °C) found at or near the surface of Venus.

If experimentally some phosphine is produced in such conditions then such a finding would suggest the reaction is likely to be more relevant to what's happening on Venus than wild theories of "life on Venus".

Water and carbon monoxide are present in the atmosphere of Venus
There's no hydrogen or oxygen in the atmosphere of Venus so I've not suggested those as initial reactants or final products.

Elemental phosphorus on the surface of Venus I have no evidence for, admittedly, so the phosphorus for my reaction may be sourced from some other precursor phosphorus compound or phosphorus-rich mineral.
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Elemental phosphorus is most unlikely to be present on Venus. The atmosphere is full of sulphuric acid, which as well as being acid is quite a powerful oxidising agent. Most likely, phosphorus would be present on Venus in oxidised form, as phosphate or phosphite minerals, or possibly even as free phosphoric acid in the clouds, along with the sulphuric acid.

If so, you would need a reducing reaction to generate phosphine. Interestingly, I see from looking it up that phosphorous acid (H3PO3) can disproportionate into phosphine and phosphoric acid:
4 H3PO3 -> PH3 + 3H3PO4

So that might be one pathway. But it will be this need for a reduction reaction that leads the researchers to wonder about bacteria.

P.S. You can also generate phosphine by hydrolysis of phosphides, but where and how would phosphides form? Some volcanic process, under reducing conditions, maybe?
 
Peter Dow said:
The overall reaction looks plausible to me if we experimentally mix phosphorus with water and carbon monoxide at the pressure (92 bar) and temperature (464 °C) found at or near the surface of Venus.
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Thought it found in the clouds at about 40°C. I didn't get the pressure

:)
 
Michael 345 said:
Thought it found in the clouds at about 40°C. I didn't get the pressure

:)
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Good point.

I must say I rather like the idea that we've all been searching for life of the wrong sort, in the wrong place, i.e. on the surface, on Mars. It would be just like the universe to make jackasses of us by developing aerial life, on a planet with a surface temperature of 400C and clouds of sulphuric acid. :biggrin:

But this phosphine discovery is a very long way from real evidence of life, of course.
 
exchemist said:
Good point.

I must say I rather like the idea that we've all been searching for life of the wrong sort, in the wrong place, i.e. on the surface, on Mars. It would be just like the universe to make jackasses of us by developing aerial life, on a planet with a surface temperature of 400C and clouds of sulphuric acid. :biggrin:

But this phosphine discovery is a very long way from real evidence of life, of course.
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https://www-nytimes-com.cdn.ampproj...com/2020/09/14/science/venus-life-clouds.html

Bit more information

And near the middle of the cloud layer, temperatures and pressures are rather Earthlike. “It’s shirt-sleeve weather, with all these tasty things to eat,” says Martha Gilmore, a Wesleyan University planetary scientist and leader of a proposed mission to Venus, referring to molecules in the planet’s air that microbes could metabolize.

https://api-nationalgeographic-com....0043438&csi=1&referrer=https://www.google.com

The plot thickens

And I am being distracted again :)

Curse being stuck in Bali

:)
 
exchemist said:
Most likely, phosphorus would be present on Venus in oxidised form, as phosphate or phosphite minerals, or possibly even as free phosphoric acid in the clouds, along with the sulphuric acid.

If so, you would need a reducing reaction to generate phosphine. Interestingly, I see from looking it up that phosphorous acid (H3PO3) can disproportionate into phosphine and phosphoric acid:
4 H3PO3 -> PH3 + 3H3PO4

So that might be one pathway.
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Agreed.

The Vega mission probe found rich reduction–oxidation chemistry between different phosphorus species and water at Venusian clouds, including phosphoric acid and Phosphorus trioxide anhydride P4O6.[22] Phosphorus trioxide anhydride P4O6 was found to be the major phosphorus species of clouds below 25km. Phosphorus trioxide anhydride can react with water[23] forming phosphorous acid which, at elevated temperature and under vacuum, disproportionates into phosphoric acid and phosphine.

https://en.wikipedia.org/wiki/Phosphine#Possible_extraterrestrial_biosignature
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Which suggests the chemical reactions -

P4O6 + 6 H2O → 4 H3PO3 → 3 H3PO4 + PH3

Those reactions cited from -

https://en.wikipedia.org/wiki/Phosphorus_trioxide#Chemical_Properties

https://en.wikipedia.org/wiki/Phosphorous_acid#Disproportionation
 
exchemist said:
And what makes you think P4O6 is lying about on the surface of Venus?
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I didn't state or imply that I thought that particularly.

What I quoted was this

The Vega mission probe found rich reduction–oxidation chemistry between different phosphorus species and water at Venusian clouds, including phosphoric acid and Phosphorus trioxide anhydride P4O6.[22] Phosphorus trioxide anhydride P4O6 was found to be the major phosphorus species of clouds below 25km. Phosphorus trioxide anhydride can react with water[23] forming phosphorous acid which, at elevated temperature and under vacuum, disproportionates into phosphoric acid and phosphine.

https://en.wikipedia.org/wiki/Phosphine#Possible_extraterrestrial_biosignature
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"clouds" aren't on the surface. The quote doesn't say anything about the surface. I didn't say anything about the surface in relation to P4O6. You seem to be the only person here who has mentioned P4O6 in relation to the surface.
 
Peter Dow said:
I didn't state or imply that I thought that particularly.

What I quoted was this


"clouds" aren't on the surface. The quote doesn't say anything about the surface. I didn't say anything about the surface in relation to P4O6. You seem to be the only person here who has mentioned P4O6 in relation to the surface.
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Oh I see.

That section seems to have been added to the Wiki article in the last 48hrs. At any rate I don't recall seeing it when I last looked at it.

I'm now trying to find out what the Vega mission actually found. It seems suspicious to me that the authors of this new work would have failed to spot something so obvious, if the Vega mission really did find P4O6 and phosphorous acid were present.
 
exchemist said:
Oh I see.

That section seems to have been added to the Wiki article in the last 48hrs. At any rate I don't recall seeing it when I last looked at it.

I'm now trying to find out what the Vega mission actually found. It seems suspicious to me that the authors of this new work would have failed to spot something so obvious, if the Vega mission really did find P4O6 and phosphorous acid were present.
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But scientists have suggested simple life forms could take refuge high in Venus’s atmosphere, where temperatures and pressures are similar to conditions found at sea level on Earth. Astronomers announced Monday that observations through ground-based telescopes detected phosphine in Venus’s clouds.

Phosphine, made by combining a phosphorus atom with three hydrogen atoms, is only generated on Earth from microbes and industrial activity, scientists said. While a sliver of Venus’s atmosphere has the right temperature and pressure to harbor life, the region strewn with droplets of sulfuric acid and lacks water.

MY HIGHLIGHTS

https://spaceflightnow.com/2020/09/...-a-privately-funded-probe-could-lead-the-way/

Nothing to do with Vega

:)
 
Michael 345 said:
But scientists have suggested simple life forms could take refuge high in Venus’s atmosphere, where temperatures and pressures are similar to conditions found at sea level on Earth. Astronomers announced Monday that observations through ground-based telescopes detected phosphine in Venus’s clouds.

Phosphine, made by combining a phosphorus atom with three hydrogen atoms, is only generated on Earth from microbes and industrial activity, scientists said. While a sliver of Venus’s atmosphere has the right temperature and pressure to harbor life, the region strewn with droplets of sulfuric acid and lacks water.

MY HIGHLIGHTS

https://spaceflightnow.com/2020/09/...-a-privately-funded-probe-could-lead-the-way/

Nothing to do with Vega

:)
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Actually I have looked this up and it is true that one of the Vega workers wrote a paper back in 1988 that said P4O6 is present in the Venusian clouds: https://www.sciencedirect.com/science/article/abs/pii/0019103589901681

The curious thing is that this latest paper in Nature which has caused all the current ballyhoo: https://www.nature.com/articles/s41550-020-1174-4
states that the Vega probe was only able to identify phosphorus as an element, rather than in what chemical compounds it was present! They go on to dismiss the possibility of H3PO3 in the clouds, as it would not be fully oxidised, whereas with all that sulphuric acid about it is a highly oxidising environment.

So I am left to wonder whether the writers of the Nature paper have overlooked this Vega finding. If so, that could be very embarrassing for them.

Alternatively, they may have convinced themselves the Vega paper is wrong. However the fact they don't reference it, even to dismiss it, suggests that isn't the explanation. But they do provide considerable supplementary information on the modelling they have done of thermodynamics and kinetics of various reactions, involving H3PO3 and conclude it can't be responsible: https://static-content.springer.com...4/MediaObjects/41550_2020_1174_MOESM1_ESM.pdf

There seems nevertheless to be a loose end here that could turn out to be important. Someone needs to tackle the issue of the Vega paper, either to take it seriously or to dismiss it.

Interesting!
 
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Michael 345 said:
Bit more info or bit of a rehash

Possible marker of life seen on the Venus - https://www.statetime24.info/2020/09/possible-marker-of-life-seen-on-venus.html

:)
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What an extraordinary source. It seems to be written in hilarious gibberish.

Specimen: "To create the observed quantity of phosphine (which consists of hydrogen and phosphorus) on Venus, terrestrial organisms would only got to work on about 10% of their productivity, consistent with the team." ???:confused:

Translated from Japanese by a bot? Anyway, incomprehensible. Did you actually read this shit? Just posted it for a laugh, I suppose.

I vill not buy zees tobacconist, it eez scratched. :D
 
Phosphorus is a relatively scarce element that appears to be necessary for life as it evolved on earth. The likely universal scarcity of phosphorus (especially on the surface of a medium sized planet orbiting a long-lived star) is one common factor people use to explain the Fermi paradox - liquid water is apparently far more common than earth-level phosphorus availability, in most analyst's assessment. Finding it on Venus in biologically relevant and available compounds of any kind would be suggestive and intriguing - not proof of anything, but a bell ringer for sure.
 
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