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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 1,531 records · Page 85
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Effect of environmental torques on short-term attitude prediction for a rolling-wheel spacecraft in a sun-synchronous orbit

A numerical evaluation and an analysis of the effects of environmental disturbance torques on the attitude of a hexagonal cylinder rolling wheel spacecraft were performed. The resulting perturbations caused by five such torques were found to be very small and exhibited linearity such that linearized equations of motion yielded accurate results over short periods and the separate perturbations contributed by each torque were additive in the sense of superposition. Linearity of the torque perturbations was not affected by moderate system design changes and persisted for torque-to-angular momentum ratios up to 100 times the nominal expected value. As these conditions include many possible applications, similar linear behavior might be anticipated for other rolling-wheel spacecraft.

Hodge, W. F.↗
NASA NTRS1972

Quasi-seasonal variation in the sun

The results of an investigation on the effects of earth seasonal changes on solar activity, particularly sunspots, are given. These results show corpuscular and electromagnetic activity increased during the equinoctial months. In addition the electromagnetic aspect tends to increase during the winter months. It was suggested that seasonal changes in sunspot numbers may be caused by the tidal forces and the processional torques exerted by the various planets in the solar atmosphere.

Chandra, S.↗
NASA NTRS1972

Variations of cosmic rays associated with chromospheric flares on the sun

Features of the cosmic-ray variations in the geomagnetic pole region and a smooth decrease in the cosmic rays intensity as a result of increased solar activity are reported. A 66-day variation of the cosmic rays was registered, in agreement with the maximum frequency and power of solar chromospheric flares.

Kozin, I. D.↗
NASA NTRS1972

The constraint of sun glint on visible data gathered by earth satellites

Sunglint simulation for the ocean surface is considered for selected satellite orbits in an attempt to optimize the selection of an orbit suitable for ocean color measurements. It appears that ocean color sensing by satellite may be most productive during a near-noon polar orbit.

Strong, A. E.↗
NASA NTRS1971

Comparison of SLAR images and small-scale, low-sun aerial photographs.

A comparison of side-looking airborne radar (SLAR) images and black and white aerial photos of similar scale and illumination of an area in the Mojave Desert of California shows that aerial photos yield far more information about geology than do SLAR images because of greater resolution, tonal range, and geometric fidelity, and easier use in stereo. Nevertheless, radar can differentiate some materials or surfaces that aerial photos cannot; thus, they should be considered as complementary, rather than competing tools in geologic investigations. The most significant advantage of SLAR, however, is its freedom from the stringent conditions of weather, date, and time that are required by small-scale aerial photos taken with a specified direction and angle of illumination. Indeed, in low latitudes, SLAR is the only way to obtain small-scale images with low illumination from certain directions; moreover, in areas of nearly continuous cloudiness, radar may be the only practical source of small-scale images.

Clark, M. M.↗
NASA NTRS1972

A search for C2/-/ in spectra of HD 201626 and the sun.

Rotational lines of the (0, 0) and (1, 1) bands of the C2(-) ion are shown to be coincident with absorption features in the CH star HD 201626 (C1, 1). Of the 72 lines of the (0, 0) band studied, the coincidences are within 0.04 A in all but two cases. These two lines are obviously blends, but of unknown origin. The identification of C2(-) must still be considered uncertain because the spectrum of HD 201626 is complex and many of the coincident lines are blended.

Fay, T. D.↗
NASA NTRS1972

The solar wind near the sun - The solar envelope.

Recent observational data and models for the structure of the solar envelope are discussed, with emphasis on those physical processes in the envelope which are decisive in determining solar wind states at 1 AU. Diffusion of relativistic solar flare protons, collisionless damping of a variable flux of hydromagnetic waves, heat transfer from electrons to protons, acceleration by Alfven waves, and magnetic field effects are examined from the viewpoint of possible contributions to solar wind behavior.

Burlaga, L. F.↗
NASA NTRS1972

Large-scale negative polarity magnetic fields on the sun and particle-emitting flares

Some observational facts about the large-scale patterns formed by solar negative polarity magnetic fields during the 19th and 20th cycles of solar activity are presented. The close relation of the position of occurrence of very large flares accompanied by cosmic ray and PCA events as well as other phenomena of solar activity during the declining part of the 19th cycle of the regularities in the internal structure of large scale negative polarity features are demonstrated.

Bumba, V.↗