Photosynthesis in Hydrogen-Dominated Atmospheres
The diversity of extrasolar planets discovered in the last decade shows that we should not be constrained to look for life in environments similar to early or present-day Earth. Super-Earth exoplanets are being discovered with increasing frequency, and some will be able to retain a stable, hydrogen-...
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doaj-3794db066a7e4d3a912a9622f8beaeb72020-11-24T23:19:47ZengMDPI AGLife2075-17292014-11-014471674410.3390/life4040716life4040716Photosynthesis in Hydrogen-Dominated AtmospheresWilliam Bains0Sara Seager1Andras Zsom2Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USADepartment of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USADepartment of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USAThe diversity of extrasolar planets discovered in the last decade shows that we should not be constrained to look for life in environments similar to early or present-day Earth. Super-Earth exoplanets are being discovered with increasing frequency, and some will be able to retain a stable, hydrogen-dominated atmosphere. We explore the possibilities for photosynthesis on a rocky planet with a thin H2-dominated atmosphere. If a rocky, H2-dominated planet harbors life, then that life is likely to convert atmospheric carbon into methane. Outgassing may also build an atmosphere in which methane is the principal carbon species. We describe the possible chemical routes for photosynthesis starting from methane and show that less energy and lower energy photons could drive CH4-based photosynthesis as compared with CO2-based photosynthesis. We find that a by-product biosignature gas is likely to be H2, which is not distinct from the hydrogen already present in the environment. Ammonia is a potential biosignature gas of hydrogenic photosynthesis that is unlikely to be generated abiologically. We suggest that the evolution of methane-based photosynthesis is at least as likely as the evolution of anoxygenic photosynthesis on Earth and may support the evolution of complex life.http://www.mdpi.com/2075-1729/4/4/716photosynthesisexoplanetbiomasshydrogen atmosphere |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
William Bains Sara Seager Andras Zsom |
spellingShingle |
William Bains Sara Seager Andras Zsom Photosynthesis in Hydrogen-Dominated Atmospheres Life photosynthesis exoplanet biomass hydrogen atmosphere |
author_facet |
William Bains Sara Seager Andras Zsom |
author_sort |
William Bains |
title |
Photosynthesis in Hydrogen-Dominated Atmospheres |
title_short |
Photosynthesis in Hydrogen-Dominated Atmospheres |
title_full |
Photosynthesis in Hydrogen-Dominated Atmospheres |
title_fullStr |
Photosynthesis in Hydrogen-Dominated Atmospheres |
title_full_unstemmed |
Photosynthesis in Hydrogen-Dominated Atmospheres |
title_sort |
photosynthesis in hydrogen-dominated atmospheres |
publisher |
MDPI AG |
series |
Life |
issn |
2075-1729 |
publishDate |
2014-11-01 |
description |
The diversity of extrasolar planets discovered in the last decade shows that we should not be constrained to look for life in environments similar to early or present-day Earth. Super-Earth exoplanets are being discovered with increasing frequency, and some will be able to retain a stable, hydrogen-dominated atmosphere. We explore the possibilities for photosynthesis on a rocky planet with a thin H2-dominated atmosphere. If a rocky, H2-dominated planet harbors life, then that life is likely to convert atmospheric carbon into methane. Outgassing may also build an atmosphere in which methane is the principal carbon species. We describe the possible chemical routes for photosynthesis starting from methane and show that less energy and lower energy photons could drive CH4-based photosynthesis as compared with CO2-based photosynthesis. We find that a by-product biosignature gas is likely to be H2, which is not distinct from the hydrogen already present in the environment. Ammonia is a potential biosignature gas of hydrogenic photosynthesis that is unlikely to be generated abiologically. We suggest that the evolution of methane-based photosynthesis is at least as likely as the evolution of anoxygenic photosynthesis on Earth and may support the evolution of complex life. |
topic |
photosynthesis exoplanet biomass hydrogen atmosphere |
url |
http://www.mdpi.com/2075-1729/4/4/716 |
work_keys_str_mv |
AT williambains photosynthesisinhydrogendominatedatmospheres AT saraseager photosynthesisinhydrogendominatedatmospheres AT andraszsom photosynthesisinhydrogendominatedatmospheres |
_version_ |
1725576929517502464 |