Reflections on O2 as a Biosignature in Exoplanetary Atmospheres.
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Cites background from "Reflections on O2 as a Biosignature..."
...However, if these catalysts are not present, strong CO features in the presence of abundant O2 and CO2 could signal a false positive scenario (Schwieterman et al., 2016; Meadows, 2017; bottom panels of Figs....
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...However, several plausible O2 false positive scenarios for planets in the habitable zone have since been identified (e.g., Wordsworth and Pierrehumbert, 2014; Luger and Barnes, 2015; Tian, 2015; Harman et al., 2015; see Meadows, 2017 for a more detailed review)....
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...This increases its detectability even in the presence of clouds, or when using techniques such as transmission spectroscopy that do not probe deep into the planetary atmosphere (Meadows, 2017)....
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...This cartoon summarizes the atmospheric mechanisms by which O2 could form abiotically at high abundance in a planetary atmosphere (Meadows, 2017)....
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...…Reinhard et al., 2017), and false positives—planetary processes that generate large (modern Earth-like) abundances of O2 abiotically (e.g., Wordsworth and Pierrehumbert, 2014; Luger and Barnes, 2015; Gao et al., 2015; Harman et al., 2015; Tian, 2015; see Meadows, 2017 for a review), being possible....
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References
2,438 citations
"Reflections on O2 as a Biosignature..." refers background in this paper
...…environmental resources required to fuel and drive photosynthesis are likely common on a terrestrial planet in the surface liquid water habitable zone—that region around a star in which an Earth-like planet could support liquid water on its surface (Kasting et al., 1993; Kopparapu et al., 2013)....
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...In particular, the environmental resources required to fuel and drive photosynthesis are likely common on a terrestrial planet in the surface liquid water habitable zone—that region around a star in which an Earth-like planet could support liquid water on its surface (Kasting et al., 1993; Kopparapu et al., 2013)....
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1,821 citations
"Reflections on O2 as a Biosignature..." refers background in this paper
...…global accumulation of O2 in the atmosphere—likely mediated by burial and removal of organic carbon from Earth’s surface environment (Kasting, 2001; Lyons et al., 2014)— evidently occurred somewhat later, between 2.45 and 2.2 Ga (Farquhar et al., 2000; Bekker et al., 2004; Canfield, 2005), with…...
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...This may have been the case on our planet, where the evolution of oxygenic photosynthesis may have predated the rise of atmospheric oxygen by hundreds of millions to billions of years (Catling et al., 2001; Catling and Kasting, 2007; Lyons et al., 2014; Planavsky et al., 2014a)....
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...Geological evidence for oxidative weathering of continents suggests that O2 may have temporarily risen to appreciable levels in our atmosphere as far back as 2.5 Ga (Anbar et al., 2007; Kaufman et al., 2007; Buick, 2008; Lyons et al., 2014)....
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...They argued that this is the lower bound for a biologically produced O2 concentration, although estimates of the Proterozoic O2 abundance vary widely (e.g., Kump, 2008; Lyons et al., 2014)....
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...Yet the irreversible, global accumulation of O2 in the atmosphere—likely mediated by burial and removal of organic carbon from Earth’s surface environment (Kasting, 2001; Lyons et al., 2014)— evidently occurred somewhat later, between 2....
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1,556 citations
"Reflections on O2 as a Biosignature..." refers background in this paper
...2 Ga (Farquhar et al., 2000; Bekker et al., 2004; Canfield, 2005), with recent sulfur isotope studies (Luo et al....
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...…of organic carbon from Earth’s surface environment (Kasting, 2001; Lyons et al., 2014)— evidently occurred somewhat later, between 2.45 and 2.2 Ga (Farquhar et al., 2000; Bekker et al., 2004; Canfield, 2005), with recent sulfur isotope studies (Luo et al., 2016) placing it at 2.33 Ga. Recent…...
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1,526 citations
"Reflections on O2 as a Biosignature..." refers background in this paper
...…environmental resources required to fuel and drive photosynthesis are likely common on a terrestrial planet in the surface liquid water habitable zone—that region around a star in which an Earth-like planet could support liquid water on its surface (Kasting et al., 1993; Kopparapu et al., 2013)....
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...In particular, the environmental resources required to fuel and drive photosynthesis are likely common on a terrestrial planet in the surface liquid water habitable zone—that region around a star in which an Earth-like planet could support liquid water on its surface (Kasting et al., 1993; Kopparapu et al., 2013)....
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...Such a planet will be outside or very close to the conservative habitable zone boundaries for its mass and atmospheric characteristics (Kopparapu et al., 2013, 2014) and, if showing the abundant O2 of a recent runaway or a hot Neptune, will also exhibit strong stratospheric H2O, but no O3 in either…...
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1,476 citations