The Viking Biological Investigation: Preliminary Results
Abstract
Three different types of biological experiments on samples of martian surface material ("soil") were conducted inside the Viking lander. In the carbon assimilation or pyrolytic release experiment, 14 CO 2 and 14 CO were exposed to soil in the presence of light. A small amount of gas was found to be converted into organic material. Heat treatment of a duplicate sample prevented such conversion. In the gas exchange experiment, soil was first humidified (exposed to water vapor) for 6 sols and then wet with a complex aqueous solution of metabolites. The gas above the soil was monitored by gas chromatography. A substantial amount of O 2 was detected in the first chromatogram taken 2.8 hours after humidification. Subsequent analyses revealed that significant increases in CO 2 and only small changes in N 2 had also occurred. In the labeled release experiment, soil was moistened with a solution containing several 14 C-labeled organic compounds. A substantial evolution of radioactive gas was registered, but did not occur with a duplicate heat-treated sample. Alternative chemical and biological interpretations are possible for these preliminary data. The experiments are still in process, and these results so far do not allow a decision regarding the existence of life on the planet Mars.
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The first life-detection attempts were made by experimental modules on NASA's Viking Mars landers in the mid-1970s.
“The first such attempts were made by experimental modules on NASA's Viking Mars landers in the mid-1970s (Klein et al., 1976).”
From The Astrobiology Primer v2.0 (2016) · cites this paper as Klein et al., 1976
The other two Viking metabolism-detecting experiments could find no evidence of biological activity down to their limit of detectability, and the GC-MS instrument could detect no trace of organic molecules in the samples.
“However, the other two metabolism-detecting experiments could find no evidence of biological activity down to their limit of detectability. Furthermore, the GC-MS instrument could detect no trace of organic molecules in the samples.”
From The Astrobiology Primer v2.0 (2016) · cites this paper as Klein et al., 1976
The Viking labeled release experiment yielded results consistent with biological activity: 14C-labeled gas was produced from surface samples, but not when they had been sterilized by heating to 160°C.
“Curiously, the labeled release experiment did indeed yield results consistent with biological activity: 14C-labeled gas was produced from the surface samples, but not when they had been sterilized by heating to 160°C (the negative control).”
From The Astrobiology Primer v2.0 (2016) · cites this paper as Klein et al., 1976
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Domagal-Goldman, S. D., Wright, K. E., Domagal-Goldman, S. D., Wright, K. E., Adamala, K., Arina de la Rubia, L., Bond, J., Dartnell, L. R., Goldman, A. D., Lynch, K., et al. (2016) · Astrobiology · doi:10.1089/ast.2015.1460 · Cited by 136 · see citing works
“Interpretation of these contradictory results has been a matter of debate for over three decades (Klein et al., 1976; Klein, 1977, 1979; Ponnamperuma et al., 1977; Owen, 1979; Navarro-González et al., 2006, 2010; Biemann, 2007).”
Reducing greenhouses and the temperature history of Earth and Mars
SAGAN, C. (1977) · Nature · doi:10.1038/269224a0 · Cited by 76 · see citing works
- Authors
- Klein, H. P., Horowitz, N. H., Levin, G. V., Oyama, V. I., Lederberg, J., Rich, A., Hubbard, J. S., Hobby, G. L., Straat, P. A., Berdahl, B. J., Carle, G. C., Brown, F. S., & Johnson, R. D.
- Affiliations
- Ames Research Center (US)
- California Institute of Technology (US)
- Biospherics Incorporated, Rockville, Maryland 20852
- Stanford University (US)
- Massachusetts Institute of Technology (US)
- Georgia Institute of Technology (US)
- Biospherics Incorporated
- TRW (United States) (US)
- ORCID
- Rich, Alexander
- Venue
- Science
- Published
- 1976-10
- Volume
- 194
- Issue
- 4260
- Pages
- 99-105
- ISSN
- 0036-8075 (ISSN-L)
- 1095-9203
- OpenAlex
- W1999536110
- Cited by
- 162
- References
- 0
- Citations by year
- 2026: 5 · 2025: 5 · 2024: 4 · 2023: 3 · 2022: 10 · 2021: 6 · 2020: 6 · 2019: 5 · 2018: 8 · 2017: 5 · 2016: 3 · 2015: 3 · 2014: 2 · 2013: 3 · 2012: 8
- FWCI
- 22.05
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Science (publishedVersion)
- PubMed (publishedVersion)
- CaltechAUTHORS (California Institute of Technology) (submittedVersion)
- Profiles in Science (submittedVersion)
- 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 › Physics and Astronomy › Astronomy and Astrophysics › Astro and Planetary Science
- Keywords
- Viking landers, Martian soil, biological investigations, carbon assimilation, gas exchange, heat treatment (food and biological processing), oxygen evolution reaction, life on Mars
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