Gases found are the same as those produced by algae on Earth
AIUI, the sensors used for this discover don't look for just _one_ gas, but as many as possible. So Oxygen is probably included in that list.
Life needs more than just oxygen gas in the atmosphere to thrive. The right combination of gasses is a better signal that life could be there versus just the presence of one gas.
Free oxygen combines with other things very readily, so you need a steady source to replenish it. Abiotic sources may not be common/strong enough. It's been a long time since I've kept tabs on that research, however.
For example, the anaerobic bacteria in your gut do not venture out into your other organs because they cannot survive in the presence of so much oxygen. There are of course membranes and such keeping them in check too, but I was surprised to learn that the oxygen gradient played a role.
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What about just looking for oxygen in a planet's atmosphere?
Not all life needs (or wants) oxygen. Plenty of earthlings die quickly when exposed to it.
Third line of the summary:
AIUI, the sensors used for this discover don't look for just _one_ gas, but as many as possible. So Oxygen is probably included in that list.
Life needs more than just oxygen gas in the atmosphere to thrive. The right combination of gasses is a better signal that life could be there versus just the presence of one gas.
Plenty of abiotic oxygen sources, even on Earth.
Free oxygen combines with other things very readily, so you need a steady source to replenish it. Abiotic sources may not be common/strong enough. It's been a long time since I've kept tabs on that research, however.
And plenty of life for which Oxygen is a poison.
For example, the anaerobic bacteria in your gut do not venture out into your other organs because they cannot survive in the presence of so much oxygen. There are of course membranes and such keeping them in check too, but I was surprised to learn that the oxygen gradient played a role.
Might be a noise floor from all the interstellar medium oxygen?