The limits of life on Earth and searching for life on Mars
Abstract
Considerations of basic properties of bacteria such as size, structure, and metabolic versatility allow one to understand how these remarkable life‐forms are so adaptable to environments previously thought to be uninhabitable. It is now appreciated that bacteria on Earth can utilize almost any redox couple that yields energy, taking advantage of this energy, while transforming the elements during metabolism. The ability to grow at the expense of inorganic redox couples allows the microbes to occupy niches not available to the more metabolically constrained eukaiyotes. Furthermore, the simplicity of the bacterial structure allows them considerably more resistance to environmental variables (pH, salinity, temperature) that are toxic or lethal to more complex organisms. This information can be used to explain the predominance of prokaryotes in extreme environments on Earth, and to speculate as to simple types of metabolism and biogeochemical cycles that may exist on this planet, Mars, and perhaps other non‐Earth environments.
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Such a biosignature of active life can be detected in situ, for example in measured concentration gradients of redox species in a column of lake water which would rapidly dissipate without life.
“Such a biosignature of active life can be detected in situ, for example in the measured concentration gradients of redox species in a column of lake water which would rapidly dissipate without life (Nealson, 1997).”
From The Astrobiology Primer v2.0 (2016) · cites this paper as Nealson, 1997
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“Such a biosignature of active life can be detected in situ, for example in the measured concentration gradients of redox species in a column of lake water which would rapidly dissipate without life (Nealson, 1997).”
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- Authors
- Nealson, K. H.
- Affiliations
- University of Wisconsin–Milwaukee (US)
- Corresponding author
- Nealson, Kenneth H.
- ORCID
- Nealson, Kenneth H.
- Venue
- Journal of Geophysical Research: Planets
- Publisher
- American Geophysical Union (AGU)
- Published
- 1997-10
- Volume
- 102
- Issue
- E10
- Pages
- 23675-23686
- ISSN
- 0148-0227 (ISSN-L)
- OpenAlex
- W1996551741
- Cited by
- 135
- References
- 5
- Citations by year
- 2026: 2 · 2025: 2 · 2024: 6 · 2022: 5 · 2021: 1 · 2020: 26 · 2019: 1 · 2018: 7 · 2017: 2 · 2016: 3 · 2014: 3 · 2013: 4 · 2012: 5
- FWCI
- 6.52
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Journal of Geophysical Research Atmospheres (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Aeronautics and Space Administration
- Japan Aerospace Exploration Agency
- Topics
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Planetary Science and Exploration
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Space Science and Extraterrestrial Life
- Physical Sciences › Environmental Science › Ecology › Microbial Community Ecology and Physiology
- Keywords
- extremophiles, bacteria, microbial metabolism, redox couples, prokaryotes, extreme environments, environmental tolerance, Mars habitability, biogeochemical cycles, search for extraterrestrial life
- MeSH terms
- Adenosine Triphosphate, Antarctic Regions, Carbon Dioxide, Environmental Microbiology, Eukaryotic Cells, Biological Evolution, Hot Temperature, Hydrogen, Oxidation-Reduction, Prokaryotic Cells, Ecosystem, Earth, Planet, Mars, Exobiology, Proton-Motive Force
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