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 plonet Mars.

Viking on Mars: The carbon assimilation experiments

“…It should be noted here that two anomalous data segments, identifiable by their non-Poisson statistics, were edited from the C6 data. Similar anomalies had been encountered in the C2 data [Klein et al, 1976]. Despite these episodes we do not doubt the validity of the results.…”

“…Preliminary accounts of the data returned from Mars have been published [Klein et al, 1976;Horowitz et al, 1976]. In this paper we summarize all of the data, including the results of two new experiments on Mars, and we conclude that they are unlikely to have a biological explanation.…”

Abiotic Ozone and Oxygen in Atmospheres Similar to Prebiotic Earth

“…The need for contextual information has been necessary when searching for life in situ Klein et al 1976;Navarro-González et al 2003;Soffen 1976) on other planets, in the rock record of the Earth, and in analyses of meteorite samples; we should anticipate a similar need when we search for life across interstellar distances.…”

Life detection experiments of the Viking Mission on Mars can be best interpreted with a Fenton oxidation reaction composed of H2O2 and Fe2+ and iron-catalysed decomposition of H2O2

“…A small amount of gas was found to be fixed by soil (interpreted to be organic material with a biological hypothesis). Heat treatment of a duplicate sample prevented this fixation (Klein et al 1976). In the gas exchange experiment, soil was first humidified with water vapour, and then wetted with a complex aqueous solution of metabolites, and the gas above the soil was analysed with gas chromatography (GC).…”