Is Atmospheric Oxygen a Planetary Signature for Life?

On Earth, oxygen made up much of our atmosphere as a direct result of photosynthetic life, thus begging the question: Is oxygen a diagnostic sign for life for terrestrial planets around sun-like stars? Only occasionally, according to Krissansen-Totton ka [2021] which model long-term evolution of planets, including magma ocean phase, volcanism, weathering, and atmospheric escape. While they show that the most terrestrial worlds can generate significant oxygen only through biology, “water worlds” and “desert worlds” can have significant oxygen accumulation even without life, as other geological processes that destroy oxygen are suppressed while atmospheric escape generates oxygen. for a long time. time. The work has implications for telescopic design and the kinds of observations needed to distinguish biota from abiotic oxygen on habitable exoplanets around sun-like stars.

Quote: Krissansen – Totton, J., Fortney, JJ, Nimmo, F., & Wogan, N. [2021]. Oxygen false positives on habitable zone planets around sun-like stars. AGU Advances, 2, e2020AV000294. https://doi.org/10.1029/2020AV000294

—Bethany Ehlmann, Editor, AGU Advances

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