Corrections in the pioneer venus sounder probe gas chromatographic analysis of the lower venus atmosphere.

Misidentification of two peaks from the Pioneer Venus sounder probe gas chromatograph (SPGC), also formerly known as the LGC, gave rise to quantitative errors in the abundances of oxygen, argon, and carbon monoxide. The argon abundance is estimated at 67 parts per million and that of carbon monoxide at 20 parts per million. At this time, no estimates for the oxygen abundance can be made.

A model of Martian surface chemistry.

Alkaline earth and alkali metal superoxides and peroxides, gamma-Fe2O3 and carbon suboxide polymer are proposed to be constituents of the Martian surface material. These reactive substances explain the water modified reactions and thermal behaviors of the Martian samples demonstrated by all of the Viking Biology Experiments. It is also proposed that the syntheses of these substances result mainly from electrical discharges between wind-mobilized particles at Martian pressures; plasmas are initiated and maintained by these discharges. Active species in the plasma either combine to form or react with inorganic surfaces to create the reactive constitutents.

Laboratory corroboration of the pioneer venus gas chromatograph analyses.

Laboratory simulation and tests of the inlet sampling system and columns of the Pioneer Venus gas chromatograph show that the sensitivity to argon is not diminished after the column regeneration step, argon isotopes are not separated, oxygen and sulfur dioxide are not produced in the inlet sampling system from sulfur trioxide, and sulfur trioxide is not formed from sulfur dioxide and oxygen. Comparisons of the volatile inventory of Venus and Earth imply similar efficiencies of early outgassing but a lower efficiency for later outgassing in the case of Venus. The high oxidation state of the Venus atmosphere in the region of cloud formation may prohibit the generation of elemental sulfur particles.

Venus lower atmospheric composition: analysis by gas chromatography.

The first gas chromatographic analysis of the lower atmosphere of Venus is reported. Three atmospheric samples were analyzed. The third of these samples showed carbon dioxide (96.4 percent), molecular nitrogen (3.41 percent), water vapor (0.135 percent), molecular oxygen [69.3 parts per million (ppm)], argon (18.6 ppm), neon (4.31 ppm), and sulfuir dioxide (186 ppm). The amounts of water vapor and sulfur dioxide detected are roughly compatible with the requirements of greenhouse models of the high surface temperature of Venus. The large positive gradient of sulfur dioxide, molecular oxygen, and water vapor from the clould tops to their bottoms, as implied by Earth-based observations and these resuilts, gives added support for the presence of major quantities of aqueous sulfuric acid in the clouds. A comparison of the inventory of inert gases found in the atmospheres of Venus, Earth, and Mars suggests that these components are due to outgassing from the planetary interiors.

The chemical activities of the Viking biology experiments and the arguments for the presence of superoxides, peroxides, gamma-Fe2O3 and carbon suboxide polymer in the Martian soil.

The evolution of N2, Ar, O2, and CO2 from Martian soil as a function of humidity in the Gas Exchange Experiment are correlated with the mean level of water vapor in the Martian atmosphere. All but O2 are associated with desorption. The evolution of oxygen is consistent with the presence of alkaline earth and alkali metal superoxides; and their peroxides and the gamma-Fe2O3 in the soil can account for the generation of radioactive gas in the Labeled Release Experiment. The slower evolution of CO2 from both the Gas Exchange Experiment and the Labeled Release Experiment are associated with the direct oxidation of organics by gamma-Fe2O3. The Pyrolytic Release Experiment's second peak may be carbon suboxide as demonstrated by laboratory experiments. A necessary condition is that the polymer exists in the Martian soil. We ascribe the activity of the surface samples to the reaction of Martian particulates with an anhydrous CO2 atmosphere activated by uv and ionizing radiations. The surface particles are ultimately altered by exposure to small but significant amounts of water at the sites. From the working model, we have predicted the peculiar nature of the chemical entities and demonstrated that the model is justified by laboratory data. The final confirmation of this model will entail a return to Mars, but the nature and implications of this chemistry for the Martian surface is predicted to reveal even more about Mars with further simulations in the laboratory.

The viking biological investigation: preliminary results.

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.

A search for viable organisms in a lunar sample.

The hypothesis that the moon could harbor viable life forms was not verified on analysis of the first samnples from the Apollo 11 mission. Biological examnination of 50 grainis of the butlk fines confirmn the negative results obtained by the Manned Spacecraft Center quarantine teamyz. No viable life forms, including terrestrial contaminants, were found when the sample was tested in 300 separate environmtenits. Only colored illorganiic artifacts, resembling mnicrobial clonies, appeared aroun1cd some particles. Manned Spacecraft Center, Houston.

The detection of optical asymmetry in biogenic molecules by gas chromatography for extraterrestrial space exploration: sample processing studies.

Life detection instrumentation proposed for space missions is necessarily based on fundamental properties of life as we know it. Most biological life detection experiments attempt to elicit biological activity such as metabolism, growth, or reproduction. In addition to these approaches, which could be definitive, it is desirable to attack the problem of life detection as depending on some chemical attribute, since it may be most difficult to elicit a biological response. Fortunately, the property of natural optical activity in organics is synonymous with life, and can be measured by physicochemical methods. The phenomenon of optical activity arising from the selection of one of two possible isomers in living systems has been explained previously. Its detection in extraterrestrial samples would be prima facie evidence for the existence of life. For this reason, among others, gas chromatographic methods for the detection of optical asymmetry have been investigated and developed in recent years. We have preferred the diastereomeric route using (+)-2-butyl derivatives of amino acids and recently we have successfully made and separated derivatives of carbohydrates from glyceraldehyde through some hexoses. A scheme for isolating, purifying and derivatizing amino acids from soils has been devised and applied to rich and poor soils alike. Since the operations involved are simple as shown schematically, the utility of automated wet chemical approaches in space exploration is a distinct possibility.

Integration of experiments for the detection of biological activity in extraterrestrial exploration.

Although many experiments have been suggested and described for the detection of biological activity in planetary exploration, each experiment has required its own sample for the detection of a specific phenomenon. An experimental design which could detect growth, catabolic and anabolic activity on a single sample is described. Growth is monitored in a liquid medium which is in contact with, and chemically influenced by, a relatively large sample. Catabolic activity is indicated by changes in the gas composition of the atmosphere above the sample. Anabolic activity is indicated by the appearance of reduced carbon compounds, from oxidized precursors, in the liquid medium.

Analysis of methods for growth detection in the search for extraterrestrial life.

In the search for life on other planets, experiments designed to detect the growth of microorganisms may prove to be definitive when coupled with chemical characterization and metabolic experiments. If organisms are not abundant, growth provides the only means for obtaining a large mass of biological material suitable for chemical compositional analyses and metabolic assays. Several methods of monitoring growth are described. Of these, optical monitoring in a unique system free of soil particles is advanced as the most appropriate. Theoretical problems related to the formulation of culture media are discussed, and several possible solutions are proposed. The sampling system, the type of monitoring, the size and placement of inoculum, and the medium volume and composition are contingent upon one another and must be integrated without sacrifice to the biological demands.