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> A chronology of oxygen accumulation suggests that free oxygen was first produced by prokaryotic and then later eukaryotic organisms in the ocean that carried

> A chronology of oxygen accumulation suggests that free oxygen was first produced by prokaryotic and then later eukaryotic organisms in the ocean that carried out photosynthesis more efficiently, producing oxygen as a waste product So oxygen is a sign of life. Can we measure oxygen's spectral line from any exoplanets? Would enough O2 suggest our kind of life is more likely there? If we could survey exoplanet atmospheres in our neighborhood for oxygen would that tell us anything about the distribution of life?

marcosdumay 7y ago
Oxygen spectral lines are mostly distinct from the non-life planet ones, so I would be greatly surprised if we couldn't measure it and if astronomers didn't do that for each planet they observed by transition.
Symmetry 7y ago
Free oxygen is a pretty good sign of life and if we were to see it in other planets' atmospheres that would be a good indication that life was there. But on the other hand, there was life on Earth for a long period of time before photosynthesis was evolved, then there was a long period of time before large amounts accumulated in the atmosphere. So while this test is relatively easy to apply across a large number of planets it would tend to give a lot of false negatives. It seems plausible that on many planets you have life evolving but because it's slow to develop photosynthesis the solar wind strips away all the hydrogen before the production of oxygen creates a protective ozone layer. Maybe that even happened on Mars, though with the lack of magnetic field there and shallow gravity well it was going to lose its hydrogen eventually even with an ozone layer.
WorldMaker 7y ago
Oxygen tests are definitely a part of exoplanet searches. Looks like determining abiotic oxygen situations in the "goldilocks zone" versus potentially biotic or life-supporting is an ongoing field of exoplanetary research: https://astrobiology.nasa.gov/news/eliminating-oxygen-false-positives-for-habitable-planets/ https://astrobiology.nasa.gov/news/eliminating-oxygen-false-... https://phys.org/news/2014-05-oxygen-exoplanet-atmospheres-life.html https://phys.org/news/2014-05-oxygen-exoplanet-atmospheres-l...

marcosdumay 7y ago

Oxygen spectral lines are mostly distinct from the non-life planet ones, so I would be greatly surprised if we couldn't measure it and if astronomers didn't do that for each planet they observed by transition.

Symmetry 7y ago

Free oxygen is a pretty good sign of life and if we were to see it in other planets' atmospheres that would be a good indication that life was there. But on the other hand, there was life on Earth for a long period of time before photosynthesis was evolved, then there was a long period of time before large amounts accumulated in the atmosphere. So while this test is relatively easy to apply across a large number of planets it would tend to give a lot of false negatives. It seems plausible that on many planets you have life evolving but because it's slow to develop photosynthesis the solar wind strips away all the hydrogen before the production of oxygen creates a protective ozone layer. Maybe that even happened on Mars, though with the lack of magnetic field there and shallow gravity well it was going to lose its hydrogen eventually even with an ozone layer.

WorldMaker 7y ago

Oxygen tests are definitely a part of exoplanet searches. Looks like determining abiotic oxygen situations in the "goldilocks zone" versus potentially biotic or life-supporting is an ongoing field of exoplanetary research: https://astrobiology.nasa.gov/news/eliminating-oxygen-false-positives-for-habitable-planets/ https://astrobiology.nasa.gov/news/eliminating-oxygen-false-... https://phys.org/news/2014-05-oxygen-exoplanet-atmospheres-life.html https://phys.org/news/2014-05-oxygen-exoplanet-atmospheres-l...