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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Survival of epiphytic bacteria from seed stored on the Long Duration Exposure Facility (LDEF)

Microbial contamination in American spacecraft has previously been documented, however, potential risks to plants and humans in future space based controlled ecological life support systems (CELSS) have yet to be addressed directly. The current study was designed to determine the survival of microorganisms exposed to the relatively harsh conditions found in low Earth orbit (LEO). Total mean dosage for flight and ground control seeds were 210.2 and 0.9 rads, respectively. Bacteria were isolated by plating samples of seedwashings onto dilute tryptic soy agar. Pure isolates of morphologically distinct bacteria were obtained by standard microbiological procedures. Bacteria were grouped according to colony type and preliminary identification was completed using a fatty acid analysis system. Bacillus spp. were the primary microorganisms that survived on seed during the experiment. Results support the hypothesis that terrestrial microorganisms can survive long periods of time in relatively harsh LEO environments.

Schuerger, Andrew C.↗
NASA NTRS1992

Laboratory experiments from the toy store

The following is a laboratory experiment designed to further understanding of materials science. This material could be taught to a typical student of materials science or manufacturing at the high school level or above. The objectives of this experiment are as follows: (1) to qualitatively demonstrate the concepts of elasticity, plasticity, and the strain rate and temperature dependence of the mechanical properties of engineering materials; (2) to qualitatively demonstrate the basics of extrusion including material flow, strain rate dependence of defects, lubrication effects, and the making of hollow shapes by extrusion (the two parts may be two separate experiments done at different times when the respective subjects are covered); and (3) to demonstrate the importance of qualitative observations and the amount of information which can be gathered without quantitative measurements.

Mcclelland, H. T.↗
NASA NTRS1992

Mechanical cooler-to-Dewar interfacing in a long-lifetime, hybrid stored cryogen system

The means for making efficient use of mechanical coolers to limit the parasitic heating into the Dewar are addressed. Thermal efficiency is achieved by minimizing the parasitic heating and thermal impedance of the cooler-to-Dewar interface within the mechanical constraints. The important issues related to compatibility with the instrument system are also briefly discussed. Parasitic heating from the nonoperating (reserved or failed) cooler pair can be reduced with an active thermal switch that isolates the cooler cold tips from the cold finger. An analysis was performed to determine the optimal switch-operating characteristics for this application. Requirements associated with the use of the coolers, analyses performed, and the interface design concept are discussed.

Hopkins, R. A.↗
NASA NTRS1992

The long hold: Storing data at the National Archives

The National Archives is, in many respects, in a unique position. For example, I find people from other organizations describing an archival medium as one which will last for three to five years. At the National Archives, we deal with the centuries, not years. From our perspective, there is no archival medium for data storage, and we do not expect there will ever be one. Predicting the long-term future of information technology beyond a mere five or ten years approaches the occult arts. But one prediction is probably safe. It is that the technology will continue to change, at least until analysts start talking about the post-information age. If we did have a medium which lasted a hundred years or longer, we probably would not have a device capable of reading it. The issue of obsolescence, as opposed to media stability, is more complex and more costly. It is especially complex at the National Archives because of two other aspects of our peculiar position. The first aspect is that we deal with incoherent data. The second is that we are charged with satisfying unknown and unknowable requirements. A brief overview of these aspects is presented.

Thibodeau, Kenneth↗
NASA NTRS1991

The long hold: Storing data at the National Archives

A description of the information collection and storage needs of the National Archives and Records Administration (NARA) is presented. The unique situation of NARA is detailed. Two aspects which make the issue of obsolescence especially complex and costly are dealing with incoherent data and satisfying unknown and unknowable requirements. The data is incoherent because it comes from a wide range of independent sources, covers unrelated subjects, and is organized and encoded in ways that are not only not controlled but often unknown until received. NARA's mission to preserve and provide access to records with enduring value makes NARA, in effect, the agent of future generations. NARA's responsibility to the future places itself is a perpetual quandary of devotion to serving needs which are unknown.

Thibodeau, Kenneth↗
NASA NTRS1958

Preliminary survey of propulsion using chemical energy stored in the upper atmosphere

Ram-jet cycles that use the chemical energy of dissociated oxygen for propulsion in the ionosphere are presented. After a review of the properties and compositions of the upper atmosphere, the external drag, recombination kinetics, and aerodynamic-heating problems of an orbiting ram jet are analyzed. The study indicates that the recombination ram jet might be useful for sustaining a satellite at an altitude of about 60 miles. Atmospheric composition and recombination-rate coefficients were too uncertain for more definite conclusions. The ram jet is a marginal device even in the optimistic view.

Baldwin, Lionel V↗