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Cryptic Photosynthesis-Extrasolar Planetary Oxygen Without a Surface Biological Signature

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Original languageEnglish
Pages (from-to)623-636
Number of pages14
JournalInternational Journal of Astrobiology
Volume9
Issue number7
DOIs
Publication statusPublished - Sep 2009

Abstract

On Earth, photosynthetic organisms are responsible for the production of virtually all the oxygen in the atmosphere. On land, vegetation reflects in the visible and leads to a "red edge,'' which developed about 450 million years ago on Earth and has been proposed as a biosignature for life on extrasolar planets. However, in many regions on Earth, particularly where surface conditions are extreme - in hot and cold deserts, for example - photosynthetic organisms can be driven into and under substrates where light is still sufficient for photosynthesis. These communities exhibit no detectable surface spectral signature to indicate life. The same is true of the assemblages of photosynthetic organisms at more than a few meters' depth in water bodies. These communities are widespread and dominate local photosynthetic productivity. We review known cryptic photosynthetic communities and their productivity. We have linked geomicrobiology with observational astronomy by calculating the disk-averaged spectra of cryptic habitats and identifying detectable features on an exoplanet dominated by such a biota. The hypothetical cryptic photosynthesis worlds discussed here are Earth analogues that show detectable atmospheric biosignatures like our own planet but do not exhibit a discernable biological surface feature in the disc-averaged spectrum.

    Research areas

  • Atmospheric gases, Bioastronomy, Extrasolar terrestrial planets, Photosynthesis, Planetary atmospheres, DEEP CHLOROPHYLL MAXIMUM, PLATELET ICE ECOSYSTEM, DENSE MICROALGAL BLOOM, ANTARCTIC SEA-ICE, SOIL CRUSTS, POLAR DESERT, CRYPTOENDOLITHIC CYANOBACTERIA, ENDOLITHIC CYANOBACTERIA, MICROBIAL COMMUNITY, SPECTRAL SIGNATURES

ID: 1497959