Viking on Mars: The carbon assimilation experiments

Horowitz, N. H.; Hobby, George L.; Hubbard, J. S.

doi:10.1029/js082i028p04659

Cited by 99 publications

(43 citation statements)

References 14 publications

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“…This was clearly stated in all published descriptions of the instrument and of the results obtained during the mission (1)(2)(3)11). The search for microbial life was the subject of three separate Viking biology experiments (12)(13)(14). The misconception presently prevailing in the astrobiology community and literature is probably caused by the effect the results from the Viking GCMS had on the interpretation of the data from these biological experiments.…”

Section: The Viking 1976 Molecular Analysis Instrumentmentioning

confidence: 99%

On the ability of the Viking gas chromatograph–mass spectrometer to detect organic matter

Biemann

2007

Proc. Natl. Acad. Sci. U.S.A.

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] claims to show that the Viking GCMS (gas chromatograph-mass spectrometer) experiment, which carried out a search for organic matter at the surface of Mars in 1976, ''may have been blind to low levels of organics.'' To rebut this assertion, the Viking experiment, test data, and results on Mars are reviewed, and the fallacies in the design, execution, and interpretation of the new experiments presented by Navarro-Gonzalez et al. are critically examined.

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Section: The Viking 1976 Molecular Analysis Instrumentmentioning

confidence: 99%

On the ability of the Viking gas chromatograph–mass spectrometer to detect organic matter

Biemann

2007

Proc. Natl. Acad. Sci. U.S.A.

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“…The examination suggests that organic compounds that arrive on Mars via meteorite are most likely to be converted to carboxylic acid derivatives that would not be easily detected by GC-MS. Organic molecules generated on Mars itself by nonbiological (11)(12)(13)(14) or (entirely hypothetical) biological synthesis (15) should suffer similar fates at or near the surface.…”

Section: Gc-ms On the Viking 1976mentioning

confidence: 99%

The missing organic molecules on Mars

Benner

Devine

Matveeva

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

377

350

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GC-MS on the Viking 1976Mars missions did not detect organic molecules on the Martian surface, even those expected from meteorite bombardment. This result suggested that the Martian regolith might hold a potent oxidant that converts all organic molecules to carbon dioxide rapidly relative to the rate at which they arrive. This conclusion is influencing the design of Mars missions. We reexamine this conclusion in light of what is known about the oxidation of organic compounds generally and the nature of organics likely to come to Mars via meteorite. We conclude that nonvolatile salts of benzenecarboxylic acids, and perhaps oxalic and acetic acid, should be metastable intermediates of meteoritic organics under oxidizing conditions. Salts of these organic acids would have been largely invisible to GC-MS. Experiments show that one of these, benzenehexacarboxylic acid (mellitic acid), is generated by oxidation of organic matter known to come to Mars, is rather stable to further oxidation, and would not have been easily detected by the Viking experiments. Approximately 2 kg of meteorite-derived mellitic acid may have been generated per m 2 of Martian surface over 3 billion years. How much remains depends on decomposition rates under Martian conditions. As available data do not require that the surface of Mars be very strongly oxidizing, some organic molecules might be found near the surface of Mars, perhaps in amounts sufficient to be a resource. Missions should seek these and recognize that these complicate the search for organics from entirely hypothetical Martian life.Viking ͉ organic compounds ͉ exobiology ͉ astrobiology

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“…Martian regolith (0.25 g sample enclosed within a 4 cc incubation chamber) was exposed to the labeled gases, with or without added water vapor, and illuminated by a simulated martian spectrum (335-1000 nm) at a flux of 20% of that predicted for the Viking sites (Horowitz et al 1977;Klein et al 1976;Klein 1978). The reactions were allowed to continue for 120 hrs at temperatures between 8 and 26°C and at pressures of approximately 10 mbar.…”

Section: Pyrolytic Release (Pr) Experimentsmentioning

confidence: 99%