<p>I was recently reading Jack R. Woods' response on this forum: <a href="https://astronomy.stackexchange.com/questions/11186/could-the-james-webb-space-telescope-detect-biosignals-on-exoplanets?rq=1">Could the James Webb Space Telescope detect biosignals on exoplanets?</a></p>
<blockquote>
<p>In an ideal situation (say looking at absorption lines of a
super-earth) there are many &quot;bio-signatures&quot;, but one of the easiest
to detect would be an ozone line in the infrared. By itself, this
would not be proof, even though there would need to be a constant
replenishing source of O2 in the atmosphere to maintain the O3. If
methane could also be found we could rightly get VERY excited since
methane and oxygen don't co-exist very well.</p>
</blockquote>
<p><strong>Question:</strong> Why wouldn't O3 detection be proof? Is there any non-biological process - already observed or theoretical - capable of generating O2 on a planetary scale with sufficient constancy to maintain an O3 layer?</p>
<p>Apparently there are theoretical processes that could actually generate O2 in the absence of life. I just don't know if it's proven:
<a href="https://www.nature.com/articles/srep13977" rel="nofollow noreferrer">Titania may produce abiotic oxygen atmospheres on habitable exoplanets | Scientific Reports</a></p>

CC BY-SA 4.0
2021-12-29T21:54:08.877Z
relevant paper https://iopscience.iop.org/article/10.3847/1538-4357/aadd9b  and probably the citations therefrom
James K
CC BY-SA 4.0
2021-12-30T12:31:43.400Z
You have to be very careful with statements like that. Besides going there and seeing the life under a microscope, there is not ever going to be an absolute proof of life on an exoplanet. This won't stop however the claims of chemical disequilibrium == life. The research literature of the recent years (e.g. https://ui.adsabs.harvard.edu/abs/2021JGRE..12606711L/abstract) constantly produces new geochemical pathways to produce biomarkers without biological action. So, you would rather have to ask "Why would $O_3$ detection be proof? How do you know it's not a false positive?"
AtmosphericPrisonEscape
CC BY-SA 4.0
2021-12-30T14:01:44.283Z
@AtmosphericPrisonEscape Yes, yes, my question was exactly whether we already knew about abiotic pathways capable of producing molecules that could be interpreted as "biosignals". And, from what I found, and also from what you sent, they exist, and they are even many; very interesting ^^
Octupos
<exoplanet><astrobiology>
Infrared ozone line detection
Octupos
# Infrared ozone line detection

(Asked by: username_0 on 2021-12-29)

I was recently reading Jack R. Woods' response on this forum: [Could the James Webb Space Telescope detect biosignals on exoplanets?](https://astronomy.stackexchange.com/questions/11186/could-the-james-webb-space-telescope-detect-biosignals-on-exoplanets?rq=1)

> In an ideal situation (say looking at absorption lines of a
> super-earth) there are many "bio-signatures", but one of the easiest
> to detect would be an ozone line in the infrared. By itself, this
> would not be proof, even though there would need to be a constant
> replenishing source of O2 in the atmosphere to maintain the O3. If
> methane could also be found we could rightly get VERY excited since
> methane and oxygen don't co-exist very well.

**Question:** Why wouldn't O3 detection be proof? Is there any non-biological process - already observed or theoretical - capable of generating O2 on a planetary scale with sufficient constancy to maintain an O3 layer?

Apparently there are theoretical processes that could actually generate O2 in the absence of life. I just don't know if it's proven:
[Titania may produce abiotic oxygen atmospheres on habitable exoplanets | Scientific Reports](https://www.nature.com/articles/srep13977)

**Tags:** exoplanet, astrobiology
> **Comments:**
> **username_1**: relevant paper https://iopscience.iop.org/article/10.3847/1538-4357/aadd9b  and probably the citations therefrom  
> **username_2**: You have to be very careful with statements like that. Besides going there and seeing the life under a microscope, there is not ever going to be an absolute proof of life on an exoplanet. This won't stop however the claims of chemical disequilibrium == life. The research literature of the recent years (e.g. https://ui.adsabs.harvard.edu/abs/2021JGRE..12606711L/abstract) constantly produces new geochemical pathways to produce biomarkers without biological action. So, you would rather have to ask "Why would $O_3$ detection be proof? How do you know it's not a false positive?"  
> **username_0**: @AtmosphericPrisonEscape Yes, yes, my question was exactly whether we already knew about abiotic pathways capable of producing molecules that could be interpreted as "biosignals". And, from what I found, and also from what you sent, they exist, and they are even many; very interesting ^^  

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## 0 answers

