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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Monte Carlo simulation of the nuclear-electromagnetic cascade development and the energy response of ionization spectrometers

Modifications to the basic computer program for performing the simulations are reported. The major changes include: (1) extension of the calculations to include the development of cascades initiated by heavy nuclei, (2) improved treatment of the nuclear disintegrations which occur during the interactions of hadrons in heavy absorbers, (3) incorporation of accurate multi-pion final-state cross sections for various interactions at accelerator energies, (4) restructuring of the program logic so that calculations can be made for sandwich-type detectors, and (5) logic modifications related to execution of the program.

Jones, W. V.↗
NASA NTRS1972

Geology of the Apollo 14 landing site.

Apollo 14 landed in the Fra Mauro region of the moon, within about 1,100 m of a 90 m high ridge of the Fra Mauro formation, interpreted as being ejecta from the Imbrium Basin. The primary geologic objective of the mission was to sample ejecta from Cone Crater, which is 340 m in diameter and penetrates at least 60 m into the ridge. Data from the mission strongly support the Imbrian ejecta origin for the Fra Mauro formation. Returned samples and photographs show that ejecta from Cone Crater is composed of composite breccias that include multiple clasts of still older, pre-Imbrian, breccias. Cone Crater ejecta displays a wide range of thermal metamorphism effects. Samples from the valley where the Lunar Module landed, which was not on a recognizable ray of ejecta from Cone Crater, are predominantly fines and poorly consolidated breccias formed by the disintegration of Fra Mauro rocks and probably are not volcanic rocks as had been postulated before the mission.

Sutton, R. L.↗
NASA NTRS1973

Spacecraft microbial burden reduction due to atmospheric entry heating - Jupiter.

An effort has been underway at Jet Propulsion Laboratory to develop the tools necessary to predict temperature histories for a typical spacecraft during inadvertent entry. In order that the results have general applicability, parametric analyses are performed. The thermal response of the spacecraft components and debris resulting from disintegration is determined. The temperature histories of small particles and composite materials, such as thermal blankets and an antenna, are given special attention. Guidelines are given to indicate the types of components and debris most likely to contain viable organisms, which could contaminate the lower layers of the Jovian atmosphere.

Gonzalez, C. C.↗
NASA NTRS1974

Radioisotope heater

One-watt heater unit is about size of flashlight cell and can be safely handled for several minutes without danger. Unit is completely sealed and can withstand buildup of helium pressure from isotope disintegration for up to 30 years. Number of units can be safely grouped together.

Smith, T. H., III↗
NASA NTRS1973

Application of SLAR for monitoring Great Lakes total ice cover

A series of X-band SLAR images is presented showing the development and disintegration of the entire ice cover on Lake Erie during the winter of 1972-1973. Simultaneous ground truth observations and ERTS-1 photography establish accurate correlations of radar responses with ice conditions. The all-weather, broad areal mapping capability of SLAR is seen to be the means for obtaining the repeated coverage needed for winter navigation on the Great Lakes.

Jirberg, R. J.↗
NASA NTRS1973

A study of degradation of plates for nickel-cadmium spacecraft cells

The relative merits of coining and not coining of sintered nickel-oxide and cadmium plates was investigated. A survey of the industry including cell manufactures and users was made and results summarized. Sample plate materials from most commercial cell suppliers were obtained and characterized for properties that may correlate with the tendency toward physical disintegration during handling and over long periods of time in the cell. Special test methods were developed to obtain comparative data in a short time. A wide range of physical properties and coining thicknesses was observed, resulting in a range of responses. The stronger, less brittle materials resisted loss of sinter better than weaker materials whether or not coined. Coining improved handling and resistance to electrochemical cycling in all materials tested. An apparent exception was found to be due to improper coining of a tapered edge.

Scott, W. R.↗
NASA NTRS1973

Cosmic dust in the atmosphere and in the interplanetary space at 1 AU today and in the early solar system

A description of techniques used in recent experiments to detect and analyze cosmic dust and micrometeorites is given and the results both from the study of lunar crater statistics and from in situ measurements are reviewed. The results from lunar crater statistics show an agreement with the results obtained from in situ measurements in interplanetary space and derived from zodiacal light measurements. The near earth results show an enhancement in the flux numbers. This can be caused either by secondary lunar debris or by disintegration of low density fireballs in the outer atmosphere.

Fechtig, H.↗
NASA NTRS1973

Application of SLAR for monitoring Great Lakes total ice cover

A series of X-band SLAR images is presented showing the development and disintegration of the entire ice cover on Lake Erie during the winter of 1972-1973. Simultaneous ground truth observations and ERTS-1 photography establish accurate correlations of radar responses with ice conditions. The all-weather, broad areal mapping capability of SLAR is seen to be the means for obtaining the repeated coverage needed for winter navigation on the Great Lakes.

Jirberg, R. J.↗
NASA NTRS1973

Comets and the formation of planets

Morphological study of the physical and dynamical processes of planet formation, with emphasis on the role of comet nuclei. A consistent model proposes the formation of comets and planets in preplanetary rings of the residual solar nebula, with subsequent ejection, chiefly by Jupiter, of the comets to Oort's (1950) sphere. Physically, dynamically, or statistically evaluated items include: (1) the total number and mass of comets in Oort's cloud; (2) reevaluation of the diameters and masses of comet nuclei; (3) the processes of nucleation from gravitational and 'Boltzmann' instabilities of gaseous media to agglomerations of particulate matter; and (4) the statistical-dynamical conditions and time scales of orbital interaction of comets with the planets and the consequences of disintegration.

Opik, E. J.↗
NASA NTRS1974

Results of investigating the physicomechanical properties of a sample of lunar surface material in a research chamber in nitrogen

Results are reported on an investigation of the mechanical properties of the lunar surface material sample returned by the Luna 16 automatic station. The study included determination of the specific weight of the surface material, the nature of its disintegration, and the determination of its compressibility characteristics, shear resistance, and bearing capacity. Quantitative data are presented on mechanical properties for the lunar surface material, many of which are determined for the first time. The instruments and experimental techniques are described.

Leonovich, A. K.↗
NASA NTRS1974

A study of degradation of plates for nickel-cadmium spacecraft cells

The relative merits of coining and not coining of sintered nickel oxide and cadmium plates was investigated. Sample plate materials from most commercial cell suppliers were obtained and characterized for properties that may correlate with the tendency toward physical disintegration during handling and over long periods of time in the cell. Special test methods were developed to obtain comparative data in a short time. A wide range of physical properties and coining thickness was observed, resulting in a range of responses. The stronger materials resisted loss of sinter better than weaker materials whether or not coined. Coining improved handling and resistance to electrochemical cycling of weaker materials. The mechanism of break-down of positive plate edges under cycling appears to be the same as that of thickening and blistering. Brittle, nonadherent sinter, resulting from certain impregnation processes, is the most vulnerable to degradation. It is concluded that the latter type of materials should be coined, but coining of strong materials is optional.

Scott, W. R.↗
NASA NTRS1975

Atmospheric effects and sidereal-diurnal variations in extended air showers

Observations are presented on the variations of extended air shower intensity with an average power of 1.4 x 10,000 and 1.4 x 100,000 particles at sea level. The effect of disintegrating particles and the essential role of cascades formed above the lower third of the atmosphere are examined. However, the authors failed to discover anisotropy of initial particles with an energy of 10 to the 14th power to 10 to the 15th power eV with an accuracy of up to 0.1%.

Efimov, N. N.↗
NASA NTRS1975

Background estimation in a (gnu e)-diffusion detector

Background conditions for detecting (gamma e)-diffusion are discussed with reference to the utilization of a hodoscope system consisting of wide area flat Geiger counters connected for coincidence and of a controllable spark chamber. When calculating the background, any organic compounds synthesized from C, O2 and H2 with radioactive admixtures is presumed to be the preferrable material for the construction of the detector. The number of background events simulating the effect sought is estimated by analyzing the spectrum of the organic glass gamma radiation caused by disintegration and fission of long lived isotopes and by nuclear reactions with the participation of alpha particles and neutrons.

Glotov, V. I.↗
NASA NTRS1975

Photonuclear interactions of ultrahigh energy cosmic rays and their astrophysical consequences

Results of detailed Monte Carlo calculations of the interaction histories of ultrahigh energy cosmic-ray nuclei with intergalactic radiation fields are presented. Estimates of these fields and empirical determinations of photonuclear cross sections are used, including multinuclear disintegrations for nuclei up to 56Fe. Intergalactic and galactic energy loss rates and nucleon loss rates for nuclei up to 56Fe are also given. Astrophysical implications are discussed in terms of expected features in the cosmic-ray spectrum between quintillion and sextillion eV for the universal and supercluster origin hypotheses. The results of these calculations indicate that ultrahigh energy cosmic rays cannot be universal in origin regardless of whether they are protons or nuclei. Both the supercluster and galactic origin hypotheses, however, are possible regardless of nuclear composition.

Puget, J. L.↗
NASA NTRS1975

A study of the icy tails of the distant comets

Properties are studied of the icy grain model for the tails of comets Baade 1955 VI and Haro-Chavira 1956 I, which have large perihelion distances. The general profiles and orientations of the tails are compared with a set of synchrones, or theoretical trajectories of particles ejected from a cometary nucleus at given instants of time. Several features observed in these comets are shown to be explained by the icy grain model, including jet activity in the coma and no appreciable broadening of the tail with increasing distance from the nucleus. It is demonstrated that the transition region between 2 and 3 AU, where water snow begins to experience rapid evaporation, has a significant effect on the dynamics of icy tails. It is suggested that the icy grains constituting these cometary tails may carry fine particles of meteoric dust which are released when the grains begin to disintegrate by evaporation.

Sekanina, Z.↗
NASA NTRS1975

Ecology and Thermal Inactivation of Microbes in and on Interplanetary Space Vehicle Components

Spores of Bacillus subtilis var. niger were heat treated in aqueous suspension at 90 C, and observed for morphological changes and loss of viability. The 5 logs reduction that occurred in broth at 90 min required 210 min in buffered water. Five characteristic changes observed after spores were exposed 120 min at 90 C in buffered water were: (1) 90% loss of spore viability, (2) 5% stainability, (3) 76% increase in spore size (as observed by scanning electron microscopy), (4) 21% of spore areas remaining refractile, and (5) an increase of 77% in packed cell volume (PCV). Stainability and PCV changes were recognized only after secondary exposure in broth. Extended heat exposure (3 h at 90 C) resulted in 99% loss of spore viability and 99% loss of stainability. After 4 hours of heat exposure, 90% of the cells disintegrated. These results suggest that early germinal changes occurr concurrently with the early changes in the heat susceptibility of dormant spores.

Reyes, A. L.↗
NASA NTRS1976

Meteoroid capture cell construction

A thin membrane covering the open side of a meteoroid capture cell causes an impacting meteoroid to disintegrate as it penetrates the membrane. The capture cell then contains and holds the meteoroid particles for later analysis.

Zook, H. A.↗