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Phosphine detected on Venus

swansont

By swansont
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Area54

Area54

Posted
Posted

https://www.nature.com/articles/s41550-020-1174-4.pdf

Extract from abstract:

Measurements of trace gases in planetary atmospheres help us explore chemical conditions different to those on Earth. Our nearest neighbour, Venus, has cloud decks that are temperate but hyperacidic. Here we report the apparent presence of phos-phine (PH3) gas in Venus’s atmosphere, where any phosphorus should be in oxidized forms. . . . .The presence of PH3 is unexplained after exhaustive study of steady-state chemistry and photochemical pathways, with no currently known abiotic production routes in Venus’s atmosphere, clouds, surface and sub-surface, or from lightning, volcanic or meteoritic delivery. PH3 could originate from unknown photochemistry or geochemistry, or, by analogy with biological production of PH3 on Earth, from the presence of life.

And from the discussion:

If no known chemical process can explain PH3 within the upper atmosphere of Venus, then it must be produced by a process not previously considered plausible for Venusian conditions. This could be unknown photochemistry or geochemistry, or possibly life. Information is lacking—as an example, the photochemistry of Venusian cloud droplets is almost completely unknown. Hence a possible droplet-phase photochemical source for PH3 must be con-sidered (even though PH3 is oxidized by sulfuric acid).

Note the caution exhibited by the authors that one hopes, but rather doubts, will be echoed by the popular press.

Duda Jarek

Duda Jarek

Posted
Posted (edited)

Oxygen-free environments seem characteristic for geological processes (?), and PH3 is similar to CH4 released by our geology - if phosphorus dominates instead of carbon, couldn't phosphine by synthesized in oxygen-free geological environments?

"Geologic emissions of methane to the atmosphere": https://pubmed.ncbi.nlm.nih.gov/12430657/

 

ps. SH2 can be produced by bacteria: https://en.wikipedia.org/wiki/Hydrogen_sulfide#Biosynthesis_in_the_body

Phosphine also occurs in Earth atmosphere  ... and Jupiter: https://en.wikipedia.org/wiki/Phosphine#Occurrence

Can be generated by bacteria: https://www.researchgate.net/publication/12507095_Phosphine_generation_by_mixed-_and_monoseptic-cultures_of_anaerobic_bacteria

Edited by Duda Jarek
hypervalent_iodine

hypervalent_iodine

Posted
Posted

I’ll admit this isn’t an area I know much about but the results seem a bit (a lot?) overstated. They aren’t even completely sure it’s phosphine. I read somewhere that the rotational transition they measured could also be within the same region that SO2 might absorb on a planet with H2SO4 clouds. Is this accurate?

2
Area54

Area54

Posted
Posted
22 minutes ago, hypervalent_iodine said:

I’ll admit this isn’t an area I know much about but the results seem a bit (a lot?) overstated.

Where is the overstatement? (I don't intend that as a belligerent observation, but a genuine query as to what you think was overstated.)

  • They do not 'headline' the possible evidence for life - the title speaks of the detection of phosphine
  • They refer in the abstract to the apparent presence of phosphine.
  • They detaill the abiotic routes to phosphine they have eliminated and note that a biotic source is suggested through analogy with its terrestrial production, not via any demonstrable pathway.
  • They searched carefully all current databases for other possible chemical species that might have been responsible for the transition signature. 
  • They discuss at some length within the paper and the supplementary material what abiotic processes they have considered and why they have rejected them.
  • They caution that other phosphene transitions should be sought in order to solidfy or disprove their belief that phosphene is responsible
  • They note that "Even if confirmed, we emphasize that the detection of PH3 is not robust evidence for life, only for anomalous and unexplained chemistry."

Where is the overstatement in all that? i genuinely don't see it.

2
hypervalent_iodine

hypervalent_iodine

Posted
Posted

I was more talking about the coverage of the article. However, they discounted the possibility of SO2 because in order to observe the results they got, it would need to be a bit hotter (about double) than what is measured in the upper clouds. Surely the simpler explanation is that they detected SO2 that was a bit hot, as opposed to phosphine? 

1
Curious layman

Curious layman

Posted
Posted
16 minutes ago, Area54 said:

 

  • They do not 'headline' the possible evidence for life - the title speaks of the detection of phosphine
  • They refer in the abstract to the apparent presence of phosphine.
  • They detaill the abiotic routes to phosphine they have eliminated and note that a biotic source is suggested through analogy with its terrestrial production, not via any demonstrable pathway.
  • They searched carefully all current databases for other possible chemical species that might have been responsible for the transition signature. 
  • They discuss at some length within the paper and the supplementary material what abiotic processes they have considered and why they have rejected them.
  • They caution that other phosphene transitions should be sought in order to solidfy or disprove their belief that phosphene is responsible
  • They note that "Even if confirmed, we emphasize that the detection of PH3 is not robust evidence for life, only for anomalous and unexplained chemistry."

Off topic, but this is brilliant.

As someone who has a habit of posting news with sensationalist articles, this a great pointer for what to look for. 

Area54

Area54

Posted
Posted
2 minutes ago, Curious layman said:

Off topic, but this is brilliant.

Thank you. If I ever make a court appearance I may call on you as a character witness.

3 minutes ago, Curious layman said:

As someone who has a habit of posting news with sensationalist articles, this a great pointer for what to look for. 

My first step with most such articles is to read the first paragraph, if it interests me then track down the original paper. Half the time the link to it is not even provided, or worse - the scientists are not named, other than top scientists at MIT, or wherever. Most papers that attract 'public' attention seem to be, fortuitously, open access. Once I've gone through the paper I might return to the popular article, but mainly to see to what extent they distorted it. This is why @hypervalent_iodine I am rather taken aback that you would focus on a popular review of the subject, rather than the subject itself. Exaggeration or misunderstanding of scientific findings by the popular media are surely a given.

So, staying on the subject: was the SO2 simply hotter? The technicality of the detection isn't just above my paygrade, its in a totally different currency, but I'm working on the basis that one or two of the authors of the paper are well versed in such matters and unlikely to make such a fundamental oversight. (Notice I said unlikely, not impossible.)

MigL

MigL

Posted
Posted

Yeah, I make Phosphine ( see my profile ).
I won't go into specifics, but it involves the continuous conversion of white Phosphorus to 20-25% red Phosphorus ( with heat ), and then reacting the slurry in very high strength Phos acid at temps of 300 degrees with superheated steam sparging, according to this patent

https://patents.google.com/patent/US3371994A/en

None of the required conditions seem unlikely to be found on Venus, so I would suspect a geological process, rather than bio-decay, as the cause ,IF it does turn out to actually be Phosphine.

2
koti

koti

Posted
Posted
7 hours ago, MigL said:

Yeah, I make Phosphine ( see my profile ).
I won't go into specifics, but it involves the continuous conversion of white Phosphorus to 20-25% red Phosphorus ( with heat ), and then reacting the slurry in very high strength Phos acid at temps of 300 degrees with superheated steam sparging, according to this patent

https://patents.google.com/patent/US3371994A/en

None of the required conditions seem unlikely to be found on Venus, so I would suspect a geological process, rather than bio-decay, as the cause ,IF it does turn out to actually be Phosphine.

Oh common MigL, I knew you were going to ruin the fun thats why I havent asked earlier. 

Peter Dow

Peter Dow

Posted
Posted
16 hours ago, Area54 said:

The presence of PH3 is unexplained after exhaustive study of steady-state chemistry and photochemical pathways, with no currently known abiotic production routes in Venus’s atmosphere, clouds, surface and sub-surface, or from lightning, volcanic or meteoritic delivery.

"Unexplained"? How hard can it be?

P4(g) + 6H2O(g) + 6CO(g) → 4PH3(g) + 6CO2(g)

 

 

 

joigus

joigus

Posted
Posted

Question for the chemistry experts:

Suppose that were phosphine they're measuring in Venus' atmosphere, and never mind where it comes from. Would it be possible for this chemical to last in those conditions for, say, billions of years after it was produced, whether biologically or otherwise? 

1 hour ago, Peter Dow said:

"Unexplained"? How hard can it be?

P4(g) + 6H2O(g) + 6CO(g) → 4PH3(g) + 6CO2(g)

 

 

 

OK. I'm no expert in chemistry, but I'm kind of an expert in explanations.

And that is not one.

Area54

Area54

Posted
Posted (edited)
7 hours ago, Peter Dow said:

"Unexplained"? How hard can it be?

P4(g) + 6H2O(g) + 6CO(g) → 4PH3(g) + 6CO2(g)

Based on that explanation, quite hard.

 

6 hours ago, joigus said:

Question for the chemistry experts:

Suppose that were phosphine they're measuring in Venus' atmosphere, and never mind where it comes from. Would it be possible for this chemical to last in those conditions for, say, billions of years after it was produced, whether biologically or otherwise?

The authors note "Solid surfaces of rocky planets present a barrier to their interiors, and PH3 would be rapidly destroyed in their highly oxidized crusts and atmospheres."

In a paper by Sousa-Silva et al the mechanisms for the destruction of PH3 are discussed in section 2.3.

For that matter, if I am understanding the discussions correctly, even in environments where PH3 is generated (the atmospheres of giant planets) it is also destroyed , there being a temperature dependent chemical equilibrium. Thus Jupiter's upper atmosphere hosts concentrations of phosphene above the equiibrium level because of ongoing convective resupply from deeper hotter levels. 

Note: Through, presumably "operator error", the link to the original paper on the subject I thought I had placed in my first post (third in the thread) is not working. This one will work. @swansont Would it be possible to correct the link in my first post? Thanks.

Edited by Area54
Insert missing link
1
MigL

MigL

Posted
Posted (edited)

Sorry Koti.
I wish Venus was like it was depicted in 1930s pulp sci-fi also.
( Edgar Rice Burroughs novels )

PH3 is a strong reducer ( stronger than  ammonia ) and readily oxidized ( actually burns ) to Phosphorus Pentoxide, or to Phosphoric acid if water is present , so it doesn't last long.
Since the Venusian atmosphere is strongly acidic, the other method for producing large amounts of Phosphine ( if actual, much higher than in Earth's atmosphere where it is due to bio-decay ), by reaction of white Phosphorus with Sodium/Potassium Hydroxide, is probably a non--starter.

Thanks for the link, Area54

Edited by MigL
1
joigus

joigus

Posted
Posted

Thanks @Area54 and @MigL. Do you know of any geological/atmospheric process that could replenish PH3?

Apparently the authors have tried some of that and ruled it out.

Also, does anybody know the answer to,

On 9/15/2020 at 12:34 AM, hypervalent_iodine said:

They aren’t even completely sure it’s phosphine. I read somewhere that the rotational transition they measured could also be within the same region that SO2 might absorb on a planet with H2SO4 clouds. Is this accurate?

?

 

 

Ken Fabian

Ken Fabian

Posted
Posted (edited)

It seems much more likely there is an unknown non-biological process making Phosphine than unknown biological processes. But news programs I've seen are hyping the "could be life" story - some with inclusion of appropriate skepticism but mostly not.

Edited by Ken Fabian
1
joigus

joigus

Posted
Posted
7 hours ago, Ken Fabian said:

It seems much more likely there is an unknown non-biological process making Phosphine than unknown biological processes. But news programs I've seen are hyping the "could be life" story - some with inclusion of appropriate skepticism but mostly not.

I generally agree. This is a very hype-sensitive topic.

Area54

Area54

Posted
Posted
8 hours ago, joigus said:

Thanks @Area54 and @MigL. Do you know of any geological/atmospheric process that could replenish PH3?

Apparently the authors have tried some of that and ruled it out.

Also, does anybody know the answer to,

I believe both these questions are addressed in the two papers I have linked two, which I repeat here for your convenience:

I think reading those directly would be more productive than relying on my garbled interpretation of them. (The reasons for discounting the SO2 are set out in the first paper; discussion of phosphine production in the second. You may need to follow further references in each case to get the complete answer you are looking for.)

@swansont Thank you for corecting my faulty link in my first post.

8 hours ago, Ken Fabian said:

It seems much more likely there is an unknown non-biological process making Phosphine than unknown biological processes. But news programs I've seen are hyping the "could be life" story - some with inclusion of appropriate skepticism but mostly not.

"We;ve seen something we don't understand" carries a lot of traction with scientists, but precious little with the general public. Whereas, "Life Jim, but not as we know it" sells copy. I would not be surprised if we learn it is the product of life, nor would I be at all surprised if it was attributed to something else. I think the latter is more likely, as is misreading of the signature.

John Cuthber

John Cuthber

Posted
Posted
22 hours ago, Peter Dow said:

"Unexplained"? How hard can it be?

P4(g) + 6H2O(g) + 6CO(g) → 4PH3(g) + 6CO2(g)

 

 

 

Why have you cited a reaction that won't work?
And also , where do you imagine it's getting the P4 from, Aldrich, eBay?

Peter Dow

Peter Dow

Posted
Posted (edited)
On 9/16/2020 at 11:07 AM, John Cuthber said:

Why have you cited a reaction that won't work?

I didn't "cite it", I worked that reaction equation out, in 10 minutes.

On 9/16/2020 at 11:07 AM, John Cuthber said:

And also , where do you imagine it's getting the P4 from, Aldrich, eBay?

I didn't imagine "P4" particularly on Venus.

Where on Venus it's getting the phosphorus from is explained here.

https://en.wikipedia.org/wiki/Phosphine#Possible_extraterrestrial_biosignature

Quote

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.

Which suggests the chemical reactions -

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

Those reactions I am citing from -

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

https://en.wikipedia.org/wiki/Phosphorous_acid#Disproportionation

On 9/15/2020 at 1:26 PM, joigus said:

OK. I'm no expert in chemistry, but I'm kind of an expert in explanations.

And that is not one.

My point is that relatively simple chemistry will provide the explanation, nothing so complicated and unlikely as "life on Venus".

 

Edited by Peter Dow
Bufofrog

Bufofrog

Posted
Posted (edited)
8 hours ago, Peter Dow said:

My point is that relatively simple chemistry will provide the explanation

Except it doesn't.  That reaction is not going to produce significant amounts of phosphine in the environment of Venus.  

Edit:  Inserted 'significant amounts' into the statement.

Edited by Bufofrog
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