Reading Earth's Ancient Atmosphere to Find Life on Nearby Exoplanets
A new analysis of NASA’s Habitable Worlds Observatory models how Earth's atmosphere would look at Archean, Proterozoic, and Phanerozoic times to estimate detection needs; it finds that, to confidently spot biosignatures on distant Earth-like planets, the telescope should aim for ~140 visible resolution to detect oxygen, ~7 UV for ozone, and ~70 near-infrared to separate CO2 and CO; even with these capabilities, life-detection is not guaranteed, and achieving such resolutions requires managing detector noise and exposure times.