The Viking biological experiments on Mars

Klein, Harold P.

doi:10.1016/0019-1035(78)90053-2

Cited by 232 publications

(183 citation statements)

References 18 publications

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“…Alternatively, the absence of organics in the soil at parts per billion levels does not preclude the presence of extant life in the martian surface. Klein (11) pointed out that the Viking TV-GC-MS would not detect Escherichia coli at levels of 10 6 per gram, which has been confirmed by recent simulations (12).…”

mentioning

confidence: 82%

The limitations on organic detection in Mars-like soils by thermal volatilization–gas chromatography–MS and their implications for the Viking results

Navarro‐González¹,

Navarro²,

Rosa³

et al. 2006

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

158

107

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The failure of Viking Lander thermal volatilization (TV) (without or with thermal degradation)-gas chromatography (GC)-MS experiments to detect organics suggests chemical rather than biological interpretations for the reactivity of the martian soil. Here, we report that TV-GC-MS may be blind to low levels of organics on astrobiology ͉ detection of organics ͉ search for martian life ͉ extreme environments ͉ deserts

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mentioning

confidence: 82%

The limitations on organic detection in Mars-like soils by thermal volatilization–gas chromatography–MS and their implications for the Viking results

Navarro‐González¹,

Navarro²,

Rosa³

et al. 2006

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

158

107

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“…9). Some models combine both a thermally stable source of oxygen (e.g., KO 2 or CaO 2 ) and a thermally labile oxidizing agent to explain the label release results (62). A generic perspective, however, notes that the compounds used in the label release experiments (aqueous formate, glycolate, glycine, D-alanine, L-alanine, D-lactate acid, and L-lactate at pH 6.2) are all ''easily oxidizable'' (63).…”

Section: Absence Of Organic Molecules Detectable By the Viking 1976 Mmentioning

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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“…The results from these two experiments, taken together with the GC-MS results, have led to the prevailing hypothesis that the Mars regolith contains one or more reactive oxidants that have the capacity to destroy carbon-containing compounds [Klein, 1978], although other interpretations have been proposed [cf. Zent and McKay, 1994].…”

Section: Relevant Viking Findingsmentioning

confidence: 99%