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
Citations
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Journal ArticleDOI
Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life
Edward W. Schwieterman,Nancy Y. Kiang,M. N. Parenteau,M. N. Parenteau,Chester E. Harman,Chester E. Harman,Chester E. Harman,Shiladitya DasSarma,Theresa Fisher,Giada Arney,Giada Arney,Hilairy E. Hartnett,Christopher T. Reinhard,Stephanie L. Olson,Stephanie L. Olson,Victoria S. Meadows,Victoria S. Meadows,Charles S. Cockell,Sara Imari Walker,John Lee Grenfell,Siddharth Hegde,Sarah Rugheimer,Renyu Hu,Timothy W. Lyons,Timothy W. Lyons +24 more
TL;DR: In this paper, a state-of-the-art overview of the current understanding of potential exoplanet biosignatures including gaseous, surface, and temporal signatures is provided.
Journal ArticleDOI
Probing the Capability of Future Direct-imaging Missions to Spectrally Constrain the Frequency of Earth-like Planets
J. Checlair,Geronimo L. Villanueva,Benjamin P. C. Hayworth,Stephanie L. Olson,Thaddeus D. Komacek,Tyler D. Robinson,Predrag Popovic,Huanzhou Yang,Dorian S. Abbot +8 more
TL;DR: In this paper, the authors explore the ability of these missions to constrain the fraction of exoEarth candidates that are Earth-like in the event of a null detection of O2 or O3 on all observed EECs.
Journal ArticleDOI
Geoscience for Understanding Habitability in the Solar System and Beyond
Véronique Dehant,Vinciane Debaille,Vera Dobos,Vera Dobos,Vera Dobos,Fabrice Gaillard,Cedric Gillmann,Steven Goderis,John Lee Grenfell,Dennis Höning,Dennis Höning,Emmanuelle Javaux,Özgür Karatekin,Alessandro Morbidelli,Lena Noack,Lena Noack,Heike Rauer,Manuel Scherf,Tilman Spohn,Paul J. Tackley,Tim Van Hoolst,Kai Wünnemann,Kai Wünnemann +22 more
TL;DR: In this article, a review of planetary habitability conditions for a terrestrial planet from the point of view of geosciences is presented, which addresses how interactions between the interior of a planet or a moon and its atmosphere and surface can affect the habitability of the celestial body.
Book ChapterDOI
Surface and Temporal Biosignatures
TL;DR: An overview of potential surface and temporal exoplanet biosignatures, reviewed Earth analogues and proposed applications based on observations and models can be found in this article, where the vegetation red-edge (VRE) remains the most well-studied surface biosignature.
Journal ArticleDOI
L 98-59: A Benchmark System of Small Planets for Future Atmospheric Characterization
Daria Pidhorodetska,Sarah E. Moran,Edward W. Schwieterman,Thomas Barclay,Thomas Barclay,Thomas Fauchez,Thomas Fauchez,Nikole K. Lewis,Elisa V. Quintana,Geronimo L. Villanueva,Shawn Domagal-Goldman,Shawn Domagal-Goldman,Joshua E. Schlieder,Emily A. Gilbert,Stephen R. Kane,Veselin B. Kostov,Veselin B. Kostov +16 more
TL;DR: In this paper, simulated transmission spectroscopy was used to evaluate the detectability of spectral features with HST and JWST assuming diverse atmospheric scenarios (e.g., atmospheres dominated by H2, H2O, CO2, or O2).
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