Researchers have found that the presence of oxygen in a planet’s atmosphere may not be a strong indicator of life:
Simulating in the lab the atmospheres of planets beyond the solar system, researchers successfully created both organic compounds and oxygen, absent of life.
The findings, published Dec. 11 by the journal ACS Earth and Space Chemistry, serve as a cautionary tale for researchers who suggest the presence of oxygen and organics on distant worlds is evidence of life there.
“Our experiments produced oxygen and organic molecules that could serve as the building blocks of life in the lab, proving that the presence of both doesn’t definitively indicate life,” says Chao He, assistant research scientist in the Johns Hopkins University Department of Earth and Planetary Sciences and the study’s first author. “Researchers need to more carefully consider how these molecules are produced.”
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The research team found multiple scenarios that produced both oxygen and organic molecules that could build sugars and amino acids—raw materials for which life could begin—such as formaldehyde and hydrogen cyanide.
“People used to suggest that oxygen and organics being present together indicates life, but we produced them abiotically in multiple simulations,” He says. “This suggests that even the co-presence of commonly accepted biosignatures could be a false positive for life.”
Johns Hopkins University, “Alien imposters: Planets with oxygen don’t necessarily have life” at Phys.org
Paper. (paywall)
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See also: Oxygen on the early Earth: More potential plot twists than a long-running soap…
But if this find holds up, it could link up with detection of life forms very early in the planet’s history.
See also: Researchers: Earth’s oxygen rose and fell several times before the Great Oxidation Event 2.2 bya
Photosynthesis pushed back even further. Time to revisit the “Boring Billion” claim
Researchers: Extreme fluctuations in oxygen levels, not gradual rise, sparked Cambrian explosion Explanations of the dramatic Cambrian explosion of life forms (540 million years ago) are a cottage industry, with arguments about oxygen a staple of the discussion. At times, it feels like trying to understand World War II without allowing for the possibility that any intention underlay any of the events. Maybe that’s why the issues can’t be resolved.
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