The search for life on other planets is one of the grand scientific goals of our time. The Decadal Survey on Astronomy and Astrophysics 2020 (Astro2020)1 sets the top priority in the coming decade to be the pursuit of a new space observatory called the Habitable World Observatory (HWO), with the goal to directly detect Earth-like planets, characterize its atmosphere, and search for biosignatures. However, whether a gas is a biosignature depends on the geochemical cycles (Shahar et al. 2019). We can’t fully identify a gas as a biosignature unless we know the planet’s (abiotic)...

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