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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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Absorption, scattering, and extinction characteristics of small solid spherical particles used as seeding agents in gaseous nuclear rocket engines
Phenomenological description of elementary particle reactions in terms of form factors
Shell stability, nuclear structure, electron scattering, and charge distribution considered in determining nuclide radius change in calcium isotopes
Characteristic spectral information obtained from surface of fine particles if spectrum is observed at high SNR or particles are compacted
Comparison of magnetic and cosmic ray data of Pioneer VI with particle guidance properties of interplanetary magnetic field
Auroral absorption analysis during geomagnetic storm, noting satellite measurement of energetic particles
Far UV transmitting windows, particularly lithium fluoride, and response measurements below 2000 angstroms, noting fabrication on solar blind materials
Solar and galactic particle spectra and composition measured with cosmic ray telescope mounted on satellite
Relationship between noctilucent clouds optical characteristics and ice sublimation in mesosphere, discussing scattering properties of particle distributions
Neutron star models, discussing crystalline crust, particle superfluid properties, rotational vortices and relation to Crab Nebula pulsar
An experiment with a ground-based polarimeter is described. It is shown that the optical properties of particles in the atmosphere can be inferred on the basis of the measured data of the radiation field. The results of the investigation demonstrate that the turbid atmosphere can be continually monitored with the aid of remote measurements of polarization and intensity.
Measurements of the downward solar radiant flux in the St. Louis area are compared with predictions from an approximate solution to the radiative transfer equation. The atmospheric aerosols were assumed to have a power size distribution and the refractive indices suggested by Fischer (1973) for an urban area. On a relatively clean day, the predictions compared well with observations. On a hazy day, the comparison was poor with the a priori choice of aerosol properties. The particles on the hazy day apparently had more submicron particles than those found in the assumed size distribution, and the particles were considerably less absorbing than those observed by Fischer. These changes could represent the effects of relative humidity and different air mass characteristics.
Recent investigations of the moon are reported. Topics discussed include the Apollo 17 site, selenography, craters, remote sensing, selenophysics, lunar surface fields and particles, magnetic properties of lunar samples, physical property measurements, surface-correlated properties, micrometeoroids, solar-system regoliths, and cosmic rays. Lunar orbital data maps are presented, and the evolution of lunar features is examined.
A history of developing opacity in the Mars southern hemisphere during the Viking extended mission has been compiled using orbiter images obtained at high altitude. Observations of changing contrasts under similar viewing conditions have been modeled by multiple-scattering intensity transfer equations that have produced a temporal description of changes in optical depth and particle-scattering properties within a network of control points. The results are presented in the form of Mercator and perspective plots for various dates.
Observations of the sunlight scattered and thermal emission from cometary dust, which may be used to infer the physical properties of the dust grains, are reviewed. Consideration is given to the observed wavelength dependence of the scattered light from cometary coma and tails, the average scattering function of the dust grains, the average grain Bond albedo, the polarization of the scattered light, and grain temperatures deduced from thermal infrared emission. The thermal properties of dust grains are illustrated for models based on magnetite or olivine grain materials, with consideration given to the variation of thermal properties with particle radius and heliocentric distance. Comparison of the models with observations indicates that a disordered or amorphous olivine composition can give a reasonable fit to the data for appropriate grain sizes and temperatures. The observations acquired are noted to indicate an optically important particle size of 1 micron, with silicate particles not larger than a few microns usually present although pure silicate grains can not be responsible for the thermal emission, and the cometary dust grains are most likely not spherical. Further observations needed in the infrared are indicated.
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Dose definitions, physical properties, mechanical properties, electrical properties, and particle definitions are listed for insulators and dielectrics, elastomeric seals and gaskets, lubricants, adhesives, and coatings.
Experimental results are presented from laboratory environment simulations of the ice particle collisional properties defining the structure and dynamical evolution of planetary rings. It is inferred from these data that there is a dependence of the interacting volume on the impact velocity. Although the volume fraction exchanged during a collision is small, the net amount of material transferred can be substantially smaller. Attention is given to the implications of these determinations for planetary ring structure and evolution.