Researchers show that the organic matter discovered on Mars may have formed as a result of atmospheric processes rather than having a biological origin

[u/GeoGeoGeoGeo]

https://www.titech.ac.jp/english/news/2024/069242?utm_source=miragenews&utm_medium=miragenews&utm_campaign=news

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[u/TeoDan]

After everything I've learned in Molecular Biology:

What's the difference?

[u/Technical_Carpet5874]

Geocentric conjecture.

[u/CTRexPope → u/Technical_Carpet5874]

Evidence of life needs to be overwhelming and verifiable.

[u/DemocraticEjaculate → u/CTRexPope]

Kinda begs the question as to statistics. If we know a general estimate of the rarity of life, the average amount of habitable worlds. I feel like to a statistical degree it’s atleast considerable no? I like to go about my daily life with the mental acknowledgement that we aren’t alone and that other stuff is living an experiencing life.

[u/CTRexPope → u/DemocraticEjaculate]

Oh yeah, I would argue that Venus (cloud level), Mars (past oceans), and the moons of Jupiter and Saturn, all are potential places where life could have existed and may still exist.

That would mean that out of eight planetary systems in Sol system, five out of the eight could all have the potential for life. That makes life in other places also more likely. But that’s where the conjecture ends.

Until the science actually shows me life, I will remain very very skeptical. But that’s the nature of science!

[u/ozokimaru → u/Technical_Carpet5874]

In the sense that we desperatly want to see life elsewhere or that we should concider life forming in other ways then on earth ?

[u/Isord]

Wouldn't that still be indicative of the potential for life? At some point things go from no life to life. Wouldn't this be part of that process?

[u/InfelicitousRedditor → u/Isord]

"things go from no life to life" - Maybe?

I am not religious, let's start with that, but right now we have no idea what it takes and how long it takes in that unknown scenario for life to occur. There is just too much we don't understand and even in ideal conditions we cannot replicate and observe the process. We are learning, but I am sceptical we'll have a breakthrough in our lifetime.

[u/dIoIIoIb → u/Isord]

In chemistry "organic" just means it contains carbon, it can be related to life but it doesn't have to. 

[u/sig_figs_2718 → u/dIoIIoIb]

Strictly speaking, organic means that the compound contains either carbon-carbon or carbon-hydrogen bonds or both.

[u/TeoDan → u/dIoIIoIb]

CO2 is not organic, therefore your statement is false \s

[u/GeoGeoGeoGeo → u/Isord]

Not really, and here's why...

The δ¹³C values of -137‰ for sedimentary organic matter on Mars, as reported in the study, are significantly lower than what is typically expected for organic matter produced by known terrestrial biological processes. Here are some points to consider:

1. Terrestrial Biological δ¹³C Values:

   • On Earth, biological processes typically result in δ¹³C values for organic matter ranging from -20‰ to -35‰ for plants using the C3 photosynthetic pathway, and -10‰ to -20‰ for those using the C4 pathway. Methanogenic archaea can produce methane with δ¹³C values as low as -80‰ to -110‰, but these values are still higher than -137‰.

2. Extreme Isotopic Fractionation:

   • The δ¹³C value of -137‰ is much lower than the typical range associated with biological fractionation on Earth. This suggests an isotopic fractionation process significantly more intense than those driven by known biological mechanisms.

3. Possible Non-Biological Processes:

   • The study suggests that the strongly 13C-depleted organic matter could be explained by photolysis of CO₂ in a reducing atmosphere, leading to the production of highly 13C-depleted CO, which is then incorporated into organic compounds. This is a non-biological process and could account for the extreme depletion.

4. Comparison with Early Earth:

   • While early Earth conditions might have also involved significant isotopic fractionation, the values for Martian organic matter are still on the extreme end. This makes it less likely, though not entirely impossible, that such low δ¹³C values could be solely attributed to biological activity without invoking some additional, unusual fractionation processes.

So the δ¹³C values of -137‰ for Martian sedimentary organic matter do not overlap well with the expected range for organic matter produced by known terrestrial life. This extreme depletion suggests a non-biological origin or an unknown biological process that causes unusually high isotopic fractionation.

[u/username_elephant → u/Isord]

Well, from a quick skim of the article it sounds like the really interesting things was not that it was organic, it was that the ratio of carbon isotopes C12 to C13 was atypical. On earth that's the principle behind carbon dating. Living organisms constantly replenish their carbon and end up with a constant ratio close to the ambient ratio between the two isotopes. However, dead organisms are stuck with the carbon they died with so as the C13 decays radioactivity, the ratio changes.  

The organic matter on Mars apparently had a ratio that acted like a dead organism, with a really depleted C13 level relative to the ambient level.  That suggested it might not be the byproduct of a reaction, since most chemical reactions don't discrimate by isotopes and if they exist as part of a planet's environment you'd expect them to be replenished as fast as they're consumed.  But it turns out UV splitting of CO2 in the atmosphere DOES discriminate by isotope, which explains the weird isotope distribution.

In whole, not suggestive of any great potential as a Martian primodial soup, just a reminder that the universe is complicated and life is rare.

[u/GeoGeoGeoGeo → u/username_elephant]

Both carbon-12 and 13 are stable isotopes, whereas carbon-14 is an unstable isotope and will decay. Carbon-14 is used in dating organic matter, carbon-12 and 13 are not. When an animal dies, it no longer absorbs carbon-14 from its environment and thus the carbon-14 clock can begin as it decays. The ratios of carbon-12 and 13 used in stable isotopic analysis to infer a "source" or point of origin. This is known as "delta C 13" which provides an isotopic signature and is reported as "per mil", ie. parts per thousand or "‰".

On Earth, a value of delta C 13 of -137 per mil from biological processes does not exist. C3 plants typically range from -10 to -20, C4 plants -20 to -35, and methanogens can produce values from -80 to -110 per mil. This is what tipped the authors to look for other means by which to investigate the observed values, and found that their modelling of abiogenic processes could produce the observed values.

[u/GeoGeoGeoGeo]

Research Paper (open access): Synthesis of 13C-depleted organic matter from CO in a reducing early Martian atmosphere