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A biomarker on Venus?

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#1 ddegroot

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Posted 14 September 2020 - 10:22 AM

As I write this, a team of scientists are announcing the discovery of a potential "biomarker" - phosphine - on Venus. Here's a link to the press briefing, which is happening right now.

 

Here's a link to a short explainer that outlines the possible significance of the discovery. And here's a measured breakdown. Oh, and here's another. 

 

UPDATE: lots of good journalism coming out. This piece from the NYT is among the best. I liked this one, too, and this one. And the Planetary Society always produces good content. 

I'll observe Venus with renewed wonder in the months and years ahead. 


Edited by ddegroot, 14 September 2020 - 11:34 AM.

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#2 BradFran

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Posted 14 September 2020 - 10:25 AM

Phosphine... how was made it on Venus? Seems to imply biochemistry. Interesting times.


Edited by BradFran, 14 September 2020 - 10:26 AM.

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#3 bunyon

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Posted 14 September 2020 - 10:33 AM

You had to know that if we were going to discover alien life in 2020, it would be because of the toxic gas it's spewing out.

 

This is actually a great test for the idea of detecting life by biomarker (the only possible way we're going to detect life on exoplanets). It's relatively straightforward to send a probe to scoop up some atmosphere and analyze it.

 

On the other hand, as a chemist who has only read summaries so far, I've always been skeptical of the "we can't think of any other way to get this chemical besides life." There are always ways to spit out weird molecules when you have access to precursors and full spectrum sunlight. 


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#4 spereira

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Posted 14 September 2020 - 11:14 AM

Moving to Science ...

 

smp


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#5 chubster4

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Posted 14 September 2020 - 11:31 AM

I remember as a kid, some books speculating Venus' clouds might cover perpetually foggy swamps - with forests even! Venus was portrayed in some sci-fi movies as harboring life. The Venera probe summarily tossed those ideas out the window. So, it's interesting to see new evidence that life still might be there, floating in those very clouds.  



#6 Napp

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Posted 14 September 2020 - 11:35 AM

Here's a link to the Royal Astronomical Society press conference announcing the detection.  The conference starts about 10min.30sec. into the video.

 

https://www.youtube....oVY81x-b8ecQXNc


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#7 Xyrus

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Posted 14 September 2020 - 12:55 PM

You had to know that if we were going to discover alien life in 2020, it would be because of the toxic gas it's spewing out.

 

This is actually a great test for the idea of detecting life by biomarker (the only possible way we're going to detect life on exoplanets). It's relatively straightforward to send a probe to scoop up some atmosphere and analyze it.

 

On the other hand, as a chemist who has only read summaries so far, I've always been skeptical of the "we can't think of any other way to get this chemical besides life." There are always ways to spit out weird molecules when you have access to precursors and full spectrum sunlight. 

Agreed. Phosphine is a very basic molecule. It's like methane, except with phosphorus instead of carbon. There are various ways it can come about, and one in particular which would work on Venus.

 

To start with, you need a phosphoric mineral (plenty in the volcanic surface rock) and sulfuric acid (plenty of that in the atmosphere). The sulfuric acid, heat, and phosphoric mineral (probably something like hydroxyapatite or something) would create phosphoric acid and other byproducts. However, phosphoric acid breaks down into phosphine at temperatures greater than 200C, which certainly is not a problem on the surface of Venus.

 

Phosphine is less dense than the CO2 which makes up 95% of the atmosphere, so it eventually rises through the atmosphere. The opacity of the atmosphere helps preserve the phosphine (breaks down in UV light, much like methane) until it makes it high enough in the atmosphere.

 

I'll need to go read the paper. It doesn't make a whole lot of sense to claim this is biomarker when all the materials are there for it to come about naturally.


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#8 Napp

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Posted 14 September 2020 - 01:26 PM

Here's the link to the scientific paper on the detection of phosphine on Venus.  It's open access.  You can read it online.  Downloading the PDF is a challenge.  I suspect there's a huge number of folks trying to download it now. 

https://www.nature.c...1550-020-1174-4



#9 payner

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Posted 14 September 2020 - 03:43 PM

I read phosphine is formed deep in the "cores" of the two giants, Jupiter and Saturn. Yes, "other ways" do result in this molecule formation.



#10 Xyrus

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Posted 14 September 2020 - 06:03 PM

Here's the link to the scientific paper on the detection of phosphine on Venus.  It's open access.  You can read it online.  Downloading the PDF is a challenge.  I suspect there's a huge number of folks trying to download it now. 

https://www.nature.c...1550-020-1174-4

I gave it quick read through, and also the referenced additional information. They claimed that the supplementary materials would cover why surface origination would not work, but I didn't see anything mentioning the make up of the surface geology or anything that would prevent the interaction between the sulfuric (and other) acids in the atmosphere and phosphorus containing minerals. There are several minerals that release phosphine (or phosphoric acid which becomes phosphine)  with ease when exposed to acids or even just water (water vapor is 0.002% of the atmosphere, which is far more than enough for the signal in the paper).

 

I don't think the paper presents a strong enough argument for a biological origin, but I'm not a geochemist so what do I know. laugh.gif


Edited by Xyrus, 14 September 2020 - 06:05 PM.


#11 llanitedave

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Posted 14 September 2020 - 10:31 PM

Agreed. Phosphine is a very basic molecule. It's like methane, except with phosphorus instead of carbon. There are various ways it can come about, and one in particular which would work on Venus.

 

To start with, you need a phosphoric mineral (plenty in the volcanic surface rock) and sulfuric acid (plenty of that in the atmosphere). The sulfuric acid, heat, and phosphoric mineral (probably something like hydroxyapatite or something) would create phosphoric acid and other byproducts. However, phosphoric acid breaks down into phosphine at temperatures greater than 200C, which certainly is not a problem on the surface of Venus.

 

Phosphine is less dense than the CO2 which makes up 95% of the atmosphere, so it eventually rises through the atmosphere. The opacity of the atmosphere helps preserve the phosphine (breaks down in UV light, much like methane) until it makes it high enough in the atmosphere.

 

I'll need to go read the paper. It doesn't make a whole lot of sense to claim this is biomarker when all the materials are there for it to come about naturally.

I was thinking along those lines.  The problem is that apparently the phosphine is not detected in gases upwelling from the lower atmosphere, or from the equator or poles, but from gases already in the upper atmosphere over the temperate regions, which should be downwelling at that point.  That complicates interpretations.


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#12 DaveC2042

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Posted 14 September 2020 - 11:16 PM

This is certainly interesting and exciting.  However, my read is that the chemistry of phosphine is not very well understood and has not had vast amounts of research devoted to it.  So assertions that it must be a biomarker are possibly a bit overoptimistic - there might be some more mundane process we haven't realised.

 

I guess another possibility is that we might have discovered something in the grey area between life and non-life.  That would be hugely important even if it's not life.


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#13 Voyager 3

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Posted 15 September 2020 - 06:43 AM

I read phosphine is formed deep in the "cores" of the two giants, Jupiter and Saturn. Yes, "other ways" do result in this molecule formation.

They say that the phosphine detected is 1000 to million times higher than what could be expected if it's of natural occurrence
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#14 bunyon

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Posted 15 September 2020 - 07:50 AM

But that assumes we know both all the relevant chemistry and all the chemicals present. Two very big assumptions. New reactions are discovered often, especially with hard to study molecules under conditions far from lab standard.

Given our present knowledge, life is one explanation. We can’t rule it out. That’s a long way from iron clad. For instance, we aren’t completely sure how terrestrial life produces phosphine. So even if this is Venusian life, it involves unknown chemistry. Once you have to invoke unknown chemistry, there isn’t really any need for life in the explanation.

It could be and it’s a really interesting discovery. But a long way to go to nail it down.
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#15 Pess

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Posted 15 September 2020 - 05:44 PM

This is certainly interesting and exciting.  However, my read is that the chemistry of phosphine is not very well understood and has not had vast amounts of research devoted to it.  So assertions that it must be a biomarker are possibly a bit overoptimistic - there might be some more mundane process we haven't realised.

 

I guess another possibility is that we might have discovered something in the grey area between life and non-life.  That would be hugely important even if it's not life.

You mean something like a virus or even  a prion?  lol

 

 

 

Pesse ( We can't even define life adequately on earth and we live here!) Mist


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#16 BrooksObs

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Posted 15 September 2020 - 05:45 PM

Boy, if I only had a dollar for every time that I've heard this sort of claim made about some feature, gas, molecule, or supposed microbe fossil associated with this, or that, celestial body being spotted/detected over the past 60 years that I've been associated with astronomy I could buy Mount Palomar outright! Please excuse me if I withhold my excitement until something more concrete than this is announced.

 

BrooksObs


Edited by BrooksObs, 15 September 2020 - 08:21 PM.

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#17 Ring_Singularity

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Posted 15 September 2020 - 11:12 PM

Agreed. Phosphine is a very basic molecule. It's like methane, except with phosphorus instead of carbon. There are various ways it can come about, and one in particular which would work on Venus.

 

To start with, you need a phosphoric mineral (plenty in the volcanic surface rock) and sulfuric acid (plenty of that in the atmosphere). The sulfuric acid, heat, and phosphoric mineral (probably something like hydroxyapatite or something) would create phosphoric acid and other byproducts. However, phosphoric acid breaks down into phosphine at temperatures greater than 200C, which certainly is not a problem on the surface of Venus.

 

Phosphine is less dense than the CO2 which makes up 95% of the atmosphere, so it eventually rises through the atmosphere. The opacity of the atmosphere helps preserve the phosphine (breaks down in UV light, much like methane) until it makes it high enough in the atmosphere.

 

I'll need to go read the paper. It doesn't make a whole lot of sense to claim this is biomarker when all the materials are there for it to come about naturally.

Life itself is "natural" and life at its very basic level is nothing more than a set of chemical reactions.


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#18 Voyager 3

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Posted 16 September 2020 - 03:09 AM

But those chemicals are complex and still we dono how life is created from none . We still didn't find how life came to existence on our own earth . First we have to know these as bunyon said . But who said life can only exist if there's water ? Why are we searching water in mars and moon ? Why not those organisms use some other liquid (ohoh I forgot that term ) like methanol ethanol liquid methane and ethane in colder outer moon or some other new exoplanets instead of water for bio chemical reactions ? We haven't fully understood it yet .
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#19 Xyrus

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Posted 16 September 2020 - 01:24 PM

But those chemicals are complex and still we dono how life is created from none . We still didn't find how life came to existence on our own earth . First we have to know these as bunyon said . But who said life can only exist if there's water ? Why are we searching water in mars and moon ? Why not those organisms use some other liquid (ohoh I forgot that term ) like methanol ethanol liquid methane and ethane in colder outer moon or some other new exoplanets instead of water for bio chemical reactions ? We haven't fully understood it yet .

We do know how life is created from "none". Fundamentally all you need is a self-replicating molecule, which actually isn't that hard to form in a primordial organic soup. The rest is just time and evolution. And by this I mean a couple billion years worth of random mutations and natural selection before anything even close to resembling a cellular organism arose.

 

What we don't know is what process(es) on Earth happened to get life started here or the specifics of how it evolved to the first organisms. We have a number of potential theories but given we only have a general idea of the initial state of the planet when life began to arise we don't know precisely how it occurred. There's a chance it may not have even started here first (panspermia). Life could have started on Mars or Venus, or even Europa and was brought here by a lucky interplanetary meteor.

 

The reason we search for water is because for carbon based life forms having a water based chemistry is the most straightforward, thus making it far more likely to occur. Could there be life using something else? Sure. There could even be silicon based life. However those scenarios are a lot more complicated and certainly aren't has common as a bunch of water and some amino acids in a puddle.


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#20 llanitedave

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Posted 16 September 2020 - 07:16 PM

The problem with using silicon as a carbon substitute is that you can't just jump a row down on the periodic table for all the other elements it would have to bond with.    For instance, the analogue of a carbon-hydrogen bond would be silicon-lithium.  But silicon and lithium don't bond the same way as do carbon and hydrogen, and for that matter, neither do silicon and hydrogen in quite the same way.  The row below oxygen is sulfur, so the analogue of carbon dioxide would be silicon disulfide.  Setting aside the question of whether silicon disulfide would be a volatile gas at the kind of temperatures and pressures envisioned for supporting silicon-based life, you start running into abundance issues with analogous elements in nature.  You also run into mobility problems.  Even if there are analogous reactions at higher temperatures and pressures of these alternative elements, the presence of those pressures makes them less likely to encounter one another in the proportions and timescales needed to carry on anything resembling a metabolism.

 

I suspect that nature would find the attempt to produce silicon-based life quite inconvenient.  Technologically, on the other hand, we might be able to do it someday.


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#21 DaveC2042

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Posted 16 September 2020 - 07:32 PM

You mean something like a virus or even  a prion?  lol

 

 

 

Pesse ( We can't even define life adequately on earth and we live here!) Mist

I was more thinking of something like a precursor to life.  Graham Cairns-Smith's clay crystals hypothesis, for example.

 

https://en.wikipedia...am_Cairns-Smith



#22 Xyrus

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Posted 16 September 2020 - 08:01 PM

The problem with using silicon as a carbon substitute is that you can't just jump a row down on the periodic table for all the other elements it would have to bond with.    For instance, the analogue of a carbon-hydrogen bond would be silicon-lithium.  But silicon and lithium don't bond the same way as do carbon and hydrogen, and for that matter, neither do silicon and hydrogen in quite the same way.  The row below oxygen is sulfur, so the analogue of carbon dioxide would be silicon disulfide.  Setting aside the question of whether silicon disulfide would be a volatile gas at the kind of temperatures and pressures envisioned for supporting silicon-based life, you start running into abundance issues with analogous elements in nature.  You also run into mobility problems.  Even if there are analogous reactions at higher temperatures and pressures of these alternative elements, the presence of those pressures makes them less likely to encounter one another in the proportions and timescales needed to carry on anything resembling a metabolism.

 

I suspect that nature would find the attempt to produce silicon-based life quite inconvenient.  Technologically, on the other hand, we might be able to do it someday.

The universe will never go out of it's way to do something complex if there is a simpler way to get it done. wink.gif

 

The universe is like a programmer. Lazy by nature, it's always looking for the simplest possible way to do something with the least amount of work, and it's more than happy with "good enough". Hence why we have quantum mechanics. It would take way too much effort to exactly track every single thing in the universe. However you can get "good enough" results and save a lot of effort if you just fudge the numbers after you reach a certain point. I mean really, the system is stable enough and who would ever look at the details at that level *angry glare at humans*.

 

We're totally throwing off the universe's groove. Everything was fine until we started looking for exploits in the game code.lol.gif


Edited by Xyrus, 16 September 2020 - 08:02 PM.

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#23 russell23

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Posted 16 September 2020 - 08:25 PM

A paper on Thursday's arXiv postings about this:

 

https://arxiv.org/abs/2009.07835

 

The main papers were in today's posting.



#24 llanitedave

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Posted 16 September 2020 - 08:48 PM

A paper on Thursday's arXiv postings about this:

 

https://arxiv.org/abs/2009.07835

 

The main papers were in today's posting.

On account of certain weakly constrained variables as well as the heuristic nature of our model, the results presented herein should be viewed with due caution.

 

The author must be British.



#25 Voyager 3

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Posted 17 September 2020 - 03:39 AM

The universe will never go out of it's way to do something complex if there is a simpler way to get it done. wink.gif

The universe is like a programmer. Lazy by nature, it's always looking for the simplest possible way to do something with the least amount of work, and it's more than happy with "good enough". Hence why we have quantum mechanics. It would take way too much effort to exactly track every single thing in the universe. However you can get "good enough" results and save a lot of effort if you just fudge the numbers after you reach a certain point. I mean really, the system is stable enough and who would ever look at the details at that level *angry glare at humans*.

We're totally throwing off the universe's groove. Everything was fine until we started looking for exploits in the game code.lol.gif

Is this called entropy ( or related to )


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