Exoplanet Biosignatures: Understanding Oxygen as a Biosignature in the Context of Its Environment

Understand

Here we review how environmental context can be used to interpret whether O2 is a biosignature in extrasolar planetary observations.

• This paper builds on the overview of current biosignature research discussed in Schwieterman et al.
• (2017), and provides an in-depth, interdisciplinary example of biosignature identification and observation that serves as a basis for the development of the general framework for biosignature assessment described in Catling et al., (2017).
• O2 is a potentially strong biosignature that was originally thought to be an unambiguous indicator for life at high-abundance.