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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Planetary quarantine program

A quantitative means was developed to investigate the sensitivity of current spacecraft sterilization plans to variations in D-values. A quantitative expression was derived to represent the distribution of D-values among a population of naturally occurring organisms. An investigation was made of (1) the inactivation of both Bacillus subtilis var. niger spores and Cape Kennedy soil spores by gamma-radiation at room temperature in a nitrogen environment, and (2) the thermoradiation resistance of Cape Kennedy soil spores at elevated temperatures below 125 C. The relation between standard survival experiments with bacterial spores in soils and results obtained on spacecraft surfaces is discussed. Sporocidal properties of aqueous formaldehyde can be increased by elevating the temperature.

Source record↗
NASA NTRS1971

Experiment S012: Micrometeorite collection

The micrometeorite activity in a near-earth environment and the effect of the environment on microorganisms were studied by exposure of polished metal and plastic surfaces to the environment outside the Gemini spacecraft. Preliminary results are summarized as follows: (1) The cumulative influx rate in the size ranges from 10 to the minus 15th power to 10 to the minus 14th power gram was approximately 2 particles/ sq m/sec, as determined on the Gemini 12 mission; (2) The cumulative influx rate in the same mass range, as determined by the data from the Gemini 9 mission was almost 200 particles/ sq m/sec; and (3) The large particle cumulative influx rate was about 3 x 0.00001 particle/ sq m/sec, with a mass of the order of 10 to the minus 7th power gram. No living organisms could be found on the sterile collecting surfaces after recovery and handling.

Hemenway, C. L.↗
NASA NTRS1971

A study of the dry heat resistance of naturally occurring organisms widely dispersed on a surface

Although Bacillus subtilis var. niger is the standard test organism for NASA planetary quarantine sterilization studies, it was found that some naturally occurring soil organisms are more heat resistant. The separation of these organisms from soil particles is described. Experiments are discussed which were designed to show that the heat resistance is a natural characteristic of the organisms, rather than a condition induced by the clumping effect of agglomerated particles and organisms.

Garst, D. M.↗
NASA NTRS1972

Enzyme activity in terrestrial soil in relation to exploration of the Martian surface

Urease activity in soil is persistent for long periods under low water, low temperature, and sterile regimes, and it was suggested that some form of enzyme-protective mechanism exists in soil. Dublin soil was extracted by sonication in water followed by adding a mixture of salts. Urease activity is associated with the organo-mineral complex thus obtained and is resistant to the activities of proteolytic enzymes. Clay free soil organic matter prepared subsequently by filtration also exhibits urease activity which is resistant to proteolysis. Models consisting of enzymes with bentonite and lignin were found to mimic this resistance to proteolysis. A model system is presented which suggests both the origin and location of soil ureases and a reason for their persistence in nature.

Ardakani, M. S.↗
NASA NTRS1972

Experimental evaluation of high-thrust, throttleable, monopropellant hydrazine reactors

Throttleable monopropellant hydrazine catalytic reactors of a size applicable to a planetary landing vehicle were designed, fabricated, and tested. An experimental evaluation of two 2670-N reactor designs was conducted. The steady state and dynamic characteristics of the thruster/valve combinations were determined. The results of the testing, including the engine characteristic velocity, smoothness of combustion, insensitivity to heat sterilization, and response during various simulated duty cycles are presented and discussed. No problems of a fundamental nature were encountered as a result of rapid dynamic throttling of these large hydrazine reactors.

Riebling, R. W.↗
NASA NTRS1972

Apollo experience report: Lunar module environmental control subsystem

A functional description of the environmental control subsystem is presented. Development, tests, checkout, and flight experiences of the subsystem are discussed; and the design fabrication, and operational difficulties associated with the various components and subassemblies are recorded. Detailed information is related concerning design changes made to, and problems encountered with, the various elements of the subsystem, such as the thermal control water sublimator, the carbon dioxide sensing and control units, and the water section. The problems associated with water sterilization, water/glycol formulation, and materials compatibility are discussed. The corrective actions taken are described with the expection that this information may be of value for future subsystems. Although the main experiences described are problem oriented, the subsystem has generally performed satisfactorily in flight.

Gillen, R. J.↗