Oxygenic Photosynthesis on an Anoxic Earth: Implications for Exoplanet Life Detection

The oxygen content of Earth’s atmosphere is a reflection of its photosynthetic biosphere—and, consequently, atmospheric oxygen is by far the most widely discussed ‘biosignature’ for remotely recognizing life on distant worlds. However, the relationship between atmospheric oxygen and biological oxygen production on Earth is complex. Biological oxygen production may predate low-level atmospheric oxygenation by more than 500 million years, and near modern levels of oxygen were delayed another 2 billion years! This talk will provide an overview of oxygen dynamics on early Earth and extend lessons from this history to the use of oxygen as a biosignature for exoplanet life detection.

Dr. Stephanie Olson is an Assistant Professor in the Department of Earth, Atmospheric, and Planetary Sciences at Purdue University. She is a biogeochemist and astrobiologist with broad interests spanning Earth history, planetary habitability, and exoplanet life detection.