Is this evidence that Venus originally had a nitrogen atmosphere?

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Summary:

Is this evidence that Venus originally had a nitrogen atmosphere and the present amount of CO2 was released by some cataclysm?

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  • #2
Klystron
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I need to finish the paper and consider the thesis but at best the author misinterprets the initial quote.

Philosopher Nicholas Rescher once wrote, "Scientific discoveries are often made not on the basis of some well-contrived plan of investigation, but through some stroke of sheer luck."
Scientific discoveries require careful preparation. The NASA team discovered good data on Venus because they designed and prepared their systems to collect atmospheric data. While Venus might be considered a calibration run for MESSENGER before testing Mercury, 'luck' in the sense of 'blind chance' was not a major factor in this discovery.

Rescher writes about plans and scripts; that long term experiments require adaptation to conditions. Perhaps serendipity would be a kinder, more meaningful description.
 
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Venus has over ~2 bars of nitrogen so that was already known. The surprise was that N2 is more abundant above the clouds than below. The prevailing assumption was that it was well-mixed, but the new data suggests the two layers don't mix well.

So it's not new evidence for a Cataclysm - there's other lines of evidence for that - but that we don't understand how atmospheres work quite as well as we thought. The global resurfacing of Venus was the Cataclysm and our present best guess places it roughly the same time that Earth was going through near global Glaciations. Were they related? The quasi-coincidence in time makes one wonder.

Summary:: Is this evidence that Venus originally had a nitrogen atmosphere and the present amount of CO2 was released by some cataclysm?

Has MESSENGER found evidence that Venus originally had a nitrogen atmosphere, and might have been more habitable, and the present amount of CO2 was released by some cataclysm afterwards?

https://phys.org/news/2020-04-lucky-messenger-upends-long-held-idea.html
 
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Summary:: Is this evidence that Venus originally had a nitrogen atmosphere and the present amount of CO2 was released by some cataclysm?
Absolutely not. qraal has succinctly summarised the significance of the findings of the research covered in the article you linked to:
The surprise was that N2 is more abundant above the clouds than below. The prevailing assumption was that it was well-mixed, but the new data suggests the two layers don't mix well.
However, perhaps some clarification is in order in regard to Cataclysms
So it's not new evidence for a Cataclysm - there's other lines of evidence for that - but that we don't understand how atmospheres work quite as well as we thought.
The global resurfacing of Venus was the Cataclysm <snip>.
The consensus view (though it is challenged by some) is that the absence of plate tectonics led to a gobal resurfacing of Venus between 600 mya and 1000 mya. This accounts for the relatively "young" surface. However, this cataclysm is not associated with the predominantly carbon dioxide atmosphere of the planet. That is a consequence of the outgassing of planet in its later stages of formation, following core formation and the onset of crystallisation of the magma ocean.

That primordial atmosphere was primarily one of CO2, with one or two bars each of water and nitrogen. The subsequent loss of water (avoided by the Earth because it was further from the sun and had a magnetic field) not only left a predominantly CO2 atmosphere, but eliminated the possibility of capturing that CO2 in minerals, as was the case on the Earth. (The Earth has about 90 bars of CO2 locked up in crustal minerals.) At the same time it prevented the development of plate tectonics, which led in turn to the global resurfacing mentioned by qraal.

Those interested in the development of the atmospheres of the terrestrial planets would find Origin and evolution of the atmospheres of early Venus, Earth and Mars an excellent read. It demonstrates the great insights that can be had from the determination of isotope ratios and a knowledge of their partitioning by various processes (and thus reveals what processes were at work). It also gives a good summary of current views on such matters of planetary formation as core formation and timing of the loss of nebula gas. I strongly recommend it.
 
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  • #5
Buzz Bloom
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Those interested in the development of the atmospheres of the terrestrial planets would find Origin and evolution of the atmospheres of early Venus, Earth and Mars an excellent read. .
Hi Ophiolite:

Your description of the reference sounds quite interesting. However, when I tried to look at it,
all I got I got was a blank screen. Is there another URL that might provide readable link?

Regards,
Buzz
 
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Hi Buzz,
that's odd. I have a copy of the paper on my hard drive, but located it online via Google Scholar in order to provide a link. I've checked it again and it opens up for me even from the copy of the link within your post. It must be recognising a cookie planted on my device and rejecting your request.

Try this: type the paper title " Origin and evolution of the atmospheres of early Venus, Earth and Mars" into Google Scholar and that should be the single option it returns.

Let me know if that works for you. It's a good paper.
 
  • #7
Ibix
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The link works for me - maybe Buzz doesn't have a PDF reader set up for his browser?
 
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  • #8
Buzz Bloom
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Hi @Ophiolite and @Ibix:

That was my problem. I did not have a PDF reader as an app in Firefox. When I fixed that I was able to read the article. Thanks very much for your help.

Regards,
Buzz
 
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  • #9
Buzz Bloom
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I would much appreciate it if someone can help me understand Figure 1 of the Lammer article. The y-axis appears to have the following label:
lEUV / lEUV-Sun .​
I get that EUV means Extreme UntraViolet, and that the ratio is relative to the sun's quantity of EUV. What I don't get is the meaning of the the lower case "l" or the upper case "I", which ever is intended.

I am guessing it means "Intensity", but where is the intensity measured to be values in the chart?

There are other things in the figure I don't get, but I would be happy to understasnd one problem at a time.

ADDED
Another guess: It is the ratio of the EUV intensity from the planet at the surface of a planet, relative to the EUV intensity arriving from the sun at the surface of the planet. Is that correct?

Regards,
Buzz
 
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I would much appreciate it if someone can help me understand Figure 1 of the Lammer article. The y-axis appears to have the following label:
lEUV / lEUV-Sun .​
I get that EUV means Extreme UntraViolet, and that the ratio is relative to the sun's quantity of EUV. What I don't get is the meaning of the the lower case "l" or the upper case "I", which ever is intended.

I am guessing it means "Intensity", but where is the intensity measured to be values in the chart?

There are other things in the figure I don't get, but I would be happy to understasnd one problem at a time.

ADDED
Another guess: It is the ratio of the EUV intensity from the planet at the surface of a planet, relative to the EUV intensity arriving from the sun at the surface of the planet. Is that correct?

Regards,
Buzz
I'm not sure the "I" is especially important, certainly not at the level I am operating at. Let's run with your "intensity" thought; it fits the context. I see the plot as the ratio of the historical sun EUV output (for three cases of rotation rate) relative to the current 'average'. We know EUV outputs are orders of magnitude higher in young stars and this higher output is related to rotation rate. As the stars age, magnetic torque slows the rotation and EUV output falls.

Since the high outputs occur during the period when atmospheres are evolving, sometimes in dramatic ways, it is important to note that there are important differences in EUV depending upon the initial rotation rate. At present, as the authors not, "we do not know the evolutionary track in high-energy radiation the Sun has taken".

Does that make sense? Or did I miss the thrust of your question.
 
  • #11
Buzz Bloom
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I'm not sure the "I" is especially important, certainly not at the level I am operating at. Let's run with your "intensity" thought; it fits the context. I see the plot as the ratio of the historical sun EUV output (for three cases of rotation rate) relative to the current 'average'. We know EUV outputs are orders of magnitude higher in young stars and this higher output is related to rotation rate. As the stars age, magnetic torque slows the rotation and EUV output falls.
Hi Ophiolite:

Thank you for your reply.
I have underlined the sentence in the above quote which I think I understand, and I would very much appreciate your letting me know whether I am correct or not.

My new understanding of what I underlined in the quote is that the Y-axis represents a ratio of (numerator) the sun's EUV at a varying time (specified in the X-axis), to the current "average" sun's EUV (specifed in the denominator), and the current "average" is calculated over a relatively short current period of time. I see that the varying values of this ratio are roughly between 1 and 360, and the value 1 occurs for an age of the sun at about 4600 Myr = 4.6 Gyr. I note that Wikipedia gives the age of the sun as 4.6 Gyr.
It formed approximately 4.6 billion ... years ago from the gravitational collapse of matter within a region of a large molecular cloud.​
I conclude that when the sun first began to emit EUV 4.6 Gyr ago, its level of emission was approximately 360 times what the sun currently emits. Is this correct?

Regards,
Buzz
 
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