Reflections on O2 as a Biosignature in Exoplanetary Atmospheres.
TLDR
Environmental factors for abiotic O2 have been identified and will improve the ability to choose optimal targets and measurements to guard against false positives, and thorough evaluation of potential biosignatures works to increase confidence in life detection.Abstract:
Oxygenic photosynthesis is Earth's dominant metabolism, having evolved to harvest the largest expected energy source at the surface of most terrestrial habitable zone planets. Using CO2 and H2O—molecules that are expected to be abundant and widespread on habitable terrestrial planets—oxygenic photosynthesis is plausible as a significant planetary process with a global impact. Photosynthetic O2 has long been considered particularly robust as a sign of life on a habitable exoplanet, due to the lack of known “false positives”—geological or photochemical processes that could also produce large quantities of stable O2. O2 has other advantages as a biosignature, including its high abundance and uniform distribution throughout the atmospheric column and its distinct, strong absorption in the visible and near-infrared. However, recent modeling work has shown that false positives for abundant oxygen or ozone could be produced by abiotic mechanisms, including photochemistry and atmospheric escape. Environm...read more
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Community Report from the Biosignatures Standards of Evidence Workshop
Victoria S. Meadows,Heather Graham,Victor Abrahamsson,Zachary R. Adam,E. Amador-French,Giada Arney,Laura M. Barge,E. Barlow,Anamaria Berea,Maitrayee Bose,D. M. Bower,Marjorie A. Chan,James Cleaves,Andrea Corpolongo,Miles Currie,Shawn Domagal-Goldman,Chuanfei Dong,Jennifer L. Eigenbrode,Allison M. L. Enright,Thomas Fauchez,Martin R. Fisk,M. Fricke,Yuka Fujii,Andrew Gangidine,Eftal Gezer,Daniel P. Glavin,Lee Grenfell,S. Harman,Roland Hatzenpichler,Libby Hausrath,Bryana L. Henderson,Sarah Stewart Johnson,Andrea J.P. Jones,Trinity L. Hamilton,Keyron Hickman-Lewis,Linda L. Jahnke,Betul Kacar,Ravi Kumar Kopparapu,Christopher P. Kempes,Adrienne Kish,Joshua Krissansen-Totton,Wil Leavitt,Yukihiro Komatsu,Tim Lichtenberg,Melody R. Lindsay,Catherine Maggiori,David J. Des Marais,Cole Mathis,Yuki Morono,Marc Neveu,Grace Ni,Conor A. Nixon,Stephanie L. Olson,Niki Parenteau,Scott Perl,Richard Quinn,Chinmayee Govinda Raj,Laura Rodriguez,Lindsay Rutter,McCullen Sandora,Britney E. Schmidt,Edward W. Schwieterman,Antígona Segura,Fatih Sekerci,Lauren M. Seyler,Harrison B. Smith,Georgia G. Soares,Sanjoy M. Som,S. S. J. A. E. A. J. -. I. Space,Astronautical Science,Bonnie Teece,Jessica M. Weber,Felisa Wolfe-Simon,Michael Wong,H. Y. J. A. E. A. J. -. I. Space,Li-Sei Young +75 more
TL;DR: Green et al. as discussed by the authors proposed a consensus framework to plan for, assess and discuss life detection claims, which could help increase the robustness of biosignature detection and interpretation, and improve communication with the scientific community and the public.
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John Lee Grenfell,Jean-Mathias Grriessmeier,Philip von Paris,Beate Patzer,Helmut Lammer,Barbara Stracke,Stefanie Gebauer,Franz Schreier,Heike Rauer +8 more
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