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| Paper: |
Testing False Positive Biosignature Scenarios with the Habitable Worlds Observatory |
| Monograph: |
10, HWO25 Proceedings Part I: Community Science Case Development Documents |
| Page: |
357 |
| Authors: |
Edward W. Schwieterman; Joshua Krissansen-Totton; Jacob Lustig-Yaeger; Sukrit Ranjan; Natalie Hinkel; Eric Mamajek; Giada Arney; Ravi Kopparapu; Victoria Meadows; Stephanie Olson; Niki Parenteau; the Living Worlds Authors |
| DOI: |
10.26624/CPCV9049 |
| Abstract: |
The search for life is one of the primary science cases for the Habitable Worlds Observatory. Important
potential biosignatures include molecular oxygen (O2) and its photochemical proxy ozone (O3), which could
signify the presence of a global biosphere powered by oxygenic photosynthesis, as is the case for Earth.
However, some proposed planetary processes—such as a runaway greenhouse coupled with massive hydrogen
escape—could lead to the abiotic accumulation of substantial free O2. It is unknown how common these
processes are. We propose collecting a valuable control sample for interpreting oxygen-based biosignatures
on temperate and potentially habitable planets by searching for O2 and/or O3 on non-habitable planets. These
non-habitable planets will include those that receive too much radiation (i.e., located in the “Venus Zone”) and
those for which habitable conditions can be excluded through spectral characterization, such as a lack of water
vapor. We identify near-UV sensitivity (0.25–0.40 µm) as a key capability for detecting O3 on hypothetical
O2-enriched Venus Zone planets, where shorter wavelengths confer advantages for inner-working-angle
(IWA) and thus implied yield. If we find abiotic O2 is uncommon on non-habitable planets, we can be
more confident in our interpretation of O2 as a biosignature on habitable worlds. On the other hand, the
detection of substantial O2 and/or O3 on non-habitable planets would validate some predictions for planetary
atmospheric evolution and demand stricter contextual standards of evidence for potential biosignatures that
may be detected in the main HWO sample of candidate ExoEarths. |
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