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Biology (GEX/LR/PR)

NSSDCA ID: 1975-075C-03

Mission Name: Viking 1 Lander
Principal Investigator:Dr. Harold P. Klein


The biology experiment searched for the presence of Martian organisms by looking for metabolic products. Three distinct instruments (pyrolytic release (PR), labeled release (LR), and gas exchange (GEX)) incubated samples of the Martian surface under a number of different environmental conditions. In some instances a sample was heat sterilized and reprocessed as a control. The PR, or carbon assimilation, instrument sought to detect the photosynthetic or chemical fixation of CO2 or CO containing C-14. The samples were incubated for several days in the presence of the radioactive gas mixture, some samples with simulated sunlight and some without. Next, each sample was heated to 120 C to remove unreacted CO2 and CO. The soil was pyrolized at 650 C and any organic products were collected in an organic vapor trap (OVT). Finally, the trap was heated to combust the organic material to CO2 and any evolved radioactive gas was measured. The LR experiment sought to detect metabolic processes through radiorespirometry. Liquid nutrients labeled with radioactive carbon were added to the samples and the atmosphere above was continuously monitored to detect any radioactive gases released from these nonvolatile nutrients. The GEX measured the production and/or uptake of CO2, N2, CH4, H2, and O2 during incubation of a soil sample. The sample was sealed and purged by He; then a mixture of He, Kr, and CO2 was introduced as an initial incubation atmosphere. After the addition of a selected quantity of a nutrient solution (saturated with the diagnostic gas, neon), the sample was incubated. At certain intervals, samples of the atmosphere were removed and analyzed by a gas chromatograph with a thermal conductivity detector.

Alternate Names

  • Viking1Lander/Biology_GEX/LR/PR_

Facts in Brief

Mass: 15 kg
Power (avg): 15 W

Funding Agency

  • NASA-Office of Space Science (United States)


  • Planetary Science: Biology
  • Planetary Science: Geology and Geophysics

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. Harold P. KleinTeam LeaderNASA Ames Research Center
Dr. Alexander RichTeam MemberMassachusetts Institute of Technology
Dr. Joshua LederbergTeam MemberStanford
Dr. Norman H. HorowitzTeam MemberCalifornia Institute of
Mr. Gilbert V. LevinTeam MemberBiospherics,
Mr. Vance I. OyamaTeam MemberNASA Ames Research Center

Selected References

  • Biemann, K., et al., The search for organic substances and inorganic volatile compounds in the surface of Mars, J. Geophys. Res., 82, No. 28, 4641-4658, doi:10.1029/JS082i028p04641, Sept. 1977.
  • Horowitz, N. H., et al., Viking on Mars: The carbon assimilation experiments, J. Geophys. Res., 82, No. 28, 4659-4662, doi:10.1029/JS082i028p04659, Sept. 1977.
  • Levin, G. V., and P. A. Straat, Recent results from the Viking labeled release experiment on Mars, J. Geophys. Res., 82, No. 28, 4663-4667, doi:10.1029/JS082i028p04663, Sept. 1977.
  • Oyama, V. I., and B. J. Berdahl, The Viking gas exchange experiment results from Chryse and Utopia surface samples, J. Geophys. Res., 82, No. 28, 4669-4676, doi:10.1029/JS082i028p04669, Sept. 1977.
  • Klein, H. P., The Viking biological investigation: General aspects, J. Geophys. Res., 82, No. 28, 4677-4680, doi:10.1029/JS082i028p04677, Sept. 1977.
  • Margulis, L., et al., The Viking mission: Implications for life on Mars, J. Mole. Evol., 14, 223-232, 1979.
  • Biemann, K., and J. M., Jr. Lavoie, Some final conclusions and supporting experiments related to the search for organic compounds on the surface of Mars, J. Geophys. Res., 84, No. B14, 8385-8390, Dec. 1979.
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