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Lehwalt, M. E.

Publications and source records attributed to Lehwalt, M. E..

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

A field gas chromatograph using technology developed for solar system exploration

Trace gas analysis is an integral part of biospheric studies. Analytical instruments, primarily gas chromatographs (GC), are capable of measuring gases and volatiles to the ppb-level in real time. Trace gases significant in the study of biocycles include nitrous oxide, hydrogen sulfide, other nitrogen and sulfur species, as well as methane and ethylene. The concept of a field gas chromatograph is derived from technology being pursued in the design of ultra-compact instruments for solar system exploration. The instrument breadboard incorporates the specialized porous column packings and the highly sensitive metastable ionization detector developed by the Solar System Exploration Office. These parts ensure a broad capability for which the analysis of ambient N2O is one example. A commercial, portable gas chromatograph is currently being extensively modified to incorporate analytical concepts and components derived from flight GC technology. Data storage devices suitable for field use are presently being studied.

Woeller, F. H.↗
NASA NTRS1978

Implications of the hypohydrous history of Mars

The extent to which fluvial processes occurred in Mars is considered with reference to the oxidation of soil organics by the gamma-Fe2O3/H2O2 system. Data from the Viking biology experiments suggest that the acidity of gamma-Fe2O3 controls the ionization of hydrogen peroxide - that is, in acid conditions and in the presence of large concentrations of formate, gamma-Fe2O3 reacts efficiently with peroxide to oxidize formate to CO2 and H2O. Fe3O4, alpha-Fe2O3, and calcite are basic and block the oxidation of formate. The properties of this system are consistent with the hypothesis that Mars has been under a severe regime of dryness.

Oyama, V. I.↗
NASA NTRS1978

Chemical interpretation of Viking Lander 1 life detection experiment

An earth-based evaluation of the Viking Lander 1 life-detection experiments was conducted using a radiofrequency glow discharge in a simulated Martian atmosphere. The Gas Exchange Experiment conducted in the humid mode released substantial amounts of CO2, O2, N2, Ar, and CO into the atmosphere, indicating that these substances were adsorbed onto the Martian soil. An adsorption potential plot is given, graphing quantity of gas against time (d). For a model surface area of 17 squares meters per gram of measured substance, oxygen adsorption was found to be relatively high, a result which tends to confirm the hypothesis that Martian oxygen exists largely in chemisorbed states or in active oxygen compounds, e.g., peroxide, superoxide, hydroperoxide

Ballou, E. V.↗
NASA NTRS1976

The search for life on Mars - Viking 1976 gas changes as indicators of biological activity

The objective of the gas exchange experiment (GEX) in the Viking lander biology instrument package is to determine whether life exists in a 1-cc Martian soil sample delivered to it. The GEX is capable of maximum flexibility while protecting the indigenous organisms from exposure to physiologically incompatible medium. The discussion covers the biological premises implemented in the GEX, the requirements for the GEX M4 medium, the operational aspects of the incubation chamber, nonbiological and biological changes, and Antarctica soil experiment. Sources of biological gas changes are examined along with ways of differentiating biological gas changes from nonbiological ones. From cold incubation of low-frequency soils, it is concluded that decisive negative tests of GEX may require extended incubations beyond the nominal mission plan of 60 days, barring any outright information that negates the presence of life on Mars.

Oyama, V. I.↗
NASA NTRS1973

Biological effects of fuel and exhaust components from spacecraft descent engines employing hydrazine

The effect of the products of the Viking terminal descent engine fuel upon possible extraterrestrial life at the Martian landing site is examined. The effects of the engine exhaust, the hydrazine fuel, and the breakdown products of the latter on terrestrial microorganisms have been studied. The results indicate that the gaseous exhaust products would probably not be hazardous to microorganisms, but that liquid hydrazine would be lethal.

Lehwalt, M. E.↗