Sciencemadness Discussion Board

Life on Venus?!

clearly_not_atara - 14-9-2020 at 15:03

https://ras.ac.uk/news-and-press/news/hints-life-venus

One thought I had was that maybe phosphine is a weak base in sulfuric acid.

But curiously, the atmosphere of Venus is strongly reducing: it contains SO2 and CO, and no O2. That does allow producing some large molecules by reducing N2, e.g. (CONH)x.

DraconicAcid - 14-9-2020 at 20:24

Strongly reducing? Moderately reducing perhaps, but I think the strongly reducing atmospheres are the ones that contain methane and H2S. It wouldn't be a surprise to find phosphine gas in the latter atmosphere.

I'm eager to find out how the phosphine comes out, particularly if it's microbes. Alien biochemistry would be amazing.

woelen - 14-9-2020 at 23:16

The atmosphere of Venus is oxidizing. Not as much as Earth's, but close to it. At the surface the main consituent is CO2, with some SO3 in gaseous form. Temperatures near the surface are around 400 C. Higher up in the atmosphere, there are clouds of concentrated H2SO4, which also is quite strongly oxidizing. At 50 km height, temperatures are more moderate, according to what I have read around 30 C.

Phosphine is quickly destroyed, even by moderately strong oxidizing agents. So, the presence of phosphine in the soup of H2SO4 at 50 km height is quite interesting. There must be a source, which constantly replenishes the PH3.

Interesting news, but still a long way to go before we can claim there is life on Venus.

wg48temp9 - 15-9-2020 at 09:45

If it turns out to be life there that will be absolutely incredible.

If nothing else it may cause a probe to be sent there that floats in the 30C layer.

Getting samples back would be really nice ^3.

Corrosive Joeseph - 15-9-2020 at 09:58

Quote: Originally posted by clearly_not_atara  

Life on Venus?!



Isn't that where women come from...


/CJ

Syn the Sizer - 15-9-2020 at 10:42

Quote: Originally posted by Corrosive Joeseph  
Quote: Originally posted by clearly_not_atara  

Life on Venus?!



Isn't that where women come from...


/CJ


I hear they go to Jupiter to get more stupider.

Jk ladies!

[Edited on 15-9-2020 by Syn the Sizer]

teodor - 16-9-2020 at 11:45

Quote: Originally posted by woelen  

Phosphine is quickly destroyed, even by moderately strong oxidizing agents. So, the presence of phosphine in the soup of H2SO4 at 50 km height is quite interesting.


Today I looked at some phosphine properties I was not aware about. Sorry, I use a quite old book "Inorganic Chemistry by Fritz Ephraim", but I believe this information is still correct:

1. Self-ignition of phosphine in air not because of phosphine itself but because of P2H4 and other higher hydrides impurities. Pure PH3 doesn't react with air in our (Earth) conditions.
2. PH3, AsH3, SbH3 in _aqueous solution_ behave as strong reducing agent, in that they not only reduce permanganate, chromate and even sulphuric and sulphurous acids, but also decompose solutions of saltes of heavy metals.
3. PH3 enters into compounds as a neutral component ... its tendency to become attached to hydrogen as a neutral component, and thus to form the phosphonium salts PH4X, corresponding to ammonium salts, is also only slight. Apart from its salts with the halogen hydrides, only that with _sulphuric acid_ id known, and even that decomposes below 0C.

So, it seams PH4 in high temp. conditions with the absence of water has more tendency to form (PH4)2SO4 than to give the hydrogen to reduce H2SO4.

[Edited on 16-9-2020 by teodor]

DraconicAcid - 16-9-2020 at 13:01

You just said that the salt with sulphuric acid decomposes above 0C. So (PH4)HSO4 (and definitely not (PH4)2SO4) will not exist at the temperatures given for the atmosphere.

unionised - 16-9-2020 at 13:18

Quote: Originally posted by teodor  

Pure PH3 doesn't react with air in our (Earth) conditions.

Real air - in the outside world- contains traces of ozone and also free radicals from photochemical reactions.
Not much of them, but they are there and they will chew up PH3.
Because the concentrations are small, the reaction would be quite slow but, over anything like geological time scales PH3 would be destroyed.

chornedsnorkack - 16-9-2020 at 23:27

Hydrogen - H2 - may be a more sluggish reducer than phosphane.
While phosphane is a weak base, how readily does it reduce sulphuric acid? Like
H3P+H2SO4=H3PO4+H2S
H3P+4H2SO4=H3PO4+4SO2+4H2O
3H3P+4H2SO4=3H3PO4+4S+4H2O
?

woelen - 16-9-2020 at 23:47

PH3 indeed does not inflame in contact with air, and it needs to be ignited before it burns. But there is a slow reaction with oxygen. I once made PH3 (which indeed did not ignite spontaneously incontact with air) and kept this gas in an inverted test tube with a stopper, the stopper immersed under water. Several days later, I saw that there was a yellowish/brown thin layer on the glass and on the surface of the water in the test tube. A considerable part of the phosphine had reacted and had formed some insoluble solid material, probably some ill-defined sub-oxide species of phosphporus.

Based on this observation I have the impression that PH3 does not have a long life in air. At very low concentrations, the reaction will be slower than over days, but even when it is over years, soon any PH3 will be gone.

Hence, I think that in an oxidizing atmosphere like Venus' the gas also quickly will be gone and be converted to oxo-species of phosphorus.

teodor - 17-9-2020 at 00:34

Quote: Originally posted by DraconicAcid  
You just said that the salt with sulphuric acid decomposes above 0C. So (PH4)HSO4 (and definitely not (PH4)2SO4) will not exist at the temperatures given for the atmosphere.


Below 0C. Yes, it's strange, I will check another sources.
Quote: Originally posted by woelen  
But there is a slow reaction with oxygen. I once made PH3 (which indeed did not ignite spontaneously incontact with air) and kept this gas in an inverted test tube with a stopper, the stopper immersed under water.


But I mentioned presence of moisture as a necessary condition of PH3 oxydation.
Oh, sorry, I didn't mention it. But this is why it reduces substances only in aqueous solution.



[Edited on 17-9-2020 by teodor]

chornedsnorkack - 17-9-2020 at 01:22

Quote: Originally posted by woelen  
Several days later, I saw that there was a yellowish/brown thin layer on the glass and on the surface of the water in the test tube. A considerable part of the phosphine had reacted and had formed some insoluble solid material, probably some ill-defined sub-oxide species of phosphporus.

Based on this observation I have the impression that PH3 does not have a long life in air. At very low concentrations, the reaction will be slower than over days, but even when it is over years, soon any PH3 will be gone.

Hence, I think that in an oxidizing atmosphere like Venus' the gas also quickly will be gone and be converted to oxo-species of phosphorus.


The thing is, then that oxo-species should also be present in Venus´ "oxidizing" atmosphere. What is phosphane oxidizing TO on Venus? And phosphoric acid is not yellowish-brown. If yellowish-brown suboxides form on Venus, they might show colour?
Unlike Earth air, where O2 specifically is abundant, on Venus a known oxidant is sulphuric acid. Does phosphane reduce sulphuric acid, and then to what?

symboom - 17-9-2020 at 16:59

To make Venus habital the Sulfuric acid would need to be converted to sulfates and Hydrogen gas which could react with the co2 at great difficulty to water and carbon the only reaction I saw is that of calcium metal or potassium superoxide. Unless a iron containing asteroid is bombarded into Venus to absorb the sulfuric acid. which seems like the most fesable method of terraforming plants already can convert carbon dioxide to oxygen and carbon

[Edited on 18-9-2020 by symboom]

zed - 12-12-2020 at 19:33

Umm. Well. Do we know what underground temperatures are like on Venus?

Hydrothermal vents? Black smokers? Underground rivers?

The surface doesn't seem very hospitable.

Now, Mars. Mars is better. But it's a micro-planet. Not enough gravity to maintain a decent atmosphere.

Not enough magnetic field, to protect the planet's atmosphere from Solar radiation.

Make Mars bigger by times three, and you've got a decent project planet.

Just gotta figure out, how to pump Mars up a little bit, without accidentally destroying Terra.

Metacelsus - 13-12-2020 at 04:56

I just want to point out that follow-up observations have cast doubt on the original claim of phosphine in the atmosphere. And it turns out the original paper used a 12-th order polynomial to fit for noise . . . yikes!

(As Von Neumann said, "With four parameters I can fit an elephant, and with five I can make him wiggle his trunk.")