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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Distribution and size of elements of Saturn's rings as inferred from 12-cm radar observations

A 64m radar antenna was used to observe Saturn's rings at 12.6 cm wavelength, with reduced Doppler spread. The results show a positive radar return corresponding to about a 60 percent return from an isotropic scatterer with the projected area of the rings, allowing for the Cassini division. A radar spectrogram of the rings is shown with power density plotted against Doppler frequency shift.

Morris, G. A., Jr.↗
NASA NTRS1974

Effect of anode ring arrangement on the spectroscopic characteristics of the NASA Lewis Bumpy Torus plasma

The modified Penning discharge in the NASA Lewis Bumpy Torus is normally produced by an anode ring at high voltage in each of the 12 magnetic mirror midplanes. For this investigation, the plasma was run with 12, 6, 3, and 1 anode rings. When 3 anode rings were used, the spectroscopically determined relative electron density and mean ion residence time increased by factors of 10 and 5, respectively, in one mode of operation. The discharge is observed to uniformly fill all bumps around the torus regardless of the anode arrangement and number. A plasma density on axis of 100 billion per cu cm is estimated for the 3-anode case in one mode of operation based on an observed discharge current to ion loss rate correlation and a measured mean ion residence time of .5 msec.

Richardson, R. W.↗
NASA NTRS1976

User's guide to computer program CIVM-JET 4B to calculate the transient structural responses of partial and/or complete structural rings to engine-rotor-fragment impact

A user-oriented computer program CIVM-JET 4B is described to predict the large-deflection elastic-plastic structural responses of fragment impacted single-layer: (a) partial-ring fragment containment or deflector structure or (b) complete-ring fragment containment structure. These two types of structures may be either free or supported in various ways. Supports accommodated include: (1) point supports such as pinned-fixed, ideally-clamped, or supported by a structural branch simulating mounting-bracket structure and (2) elastic foundation support distributed over selected regions of the structure. The initial geometry of each partial or complete ring may be circular or arbitrarily curved; uniform or variable thicknesses of the structure are accommodated. The structural material is assumed to be initially isotropic; strain hardening and strain rate effects are taken into account.

Stagliano, T. R.↗
NASA NTRS1976

Orbital changes of the gaseous ring around B sub e stars

In order to understand the seemingly erratic V/R variations and radial velocity curves of emission edges and central absorption of some Be stars, a theory is advanced to explain the changes of structure of the gaseous ring around these stars. The theory is based on the interaction between the existing ring and the newly ejected matter from the star. It shows that the structural change of the ring is completely controlled by the angular momentum input factor and the dissipation factor. In light of this understanding, the observed results of beta Mon and Pi Aqr. are interpreted.

Huang, S. S.↗
NASA NTRS1975

The rings of Saturn

This paper reviews observations of the rings of Saturn at visual, infrared, and radio wavelengths. Critical assessments are made of attempts to derive the physical characteristics of the rings from these measurements. A discussion is also given of the origin and evolution of the rings.

Pollack, J. B.↗
NASA NTRS1975

The thermal radiation of Saturn and its rings

Infrared observations of Saturn from 5 to 40 microns are described. There is intense limb brightening at 12.35 microns over the southern polar cap. The C ring is anomalously bright at 10 and 20 microns and has bluer (hotter) colors than the A and B rings. The ring spectra have been extrapolated beyond 40 microns and subtracted from low-resolution far-infrared measurements to show that the far-infrared spectrum of the disk of Saturn is qualitatively similar to that of Jupiter and that Saturn radiates 2.5 plus or minus 0.6 times the energy it absorbs from the sun.

Rieke, G. H.↗
NASA NTRS1976

Azimuthal brightness variations of Saturn's rings

Saturn's ring A exhibits a variation in brightness with azimuth (with orbital phase of the ring particles). Maximum brightness occurs at true orbital phase angles of about 45 and 225 deg; minimum brightness-occurs at about 135 and 315 deg, where the eastern ansa is taken as zero deg. No such effect appears to exist for ring B.

Lumme, K.↗
NASA NTRS1977

Analytical calculation of the areas of Saturn's disk and rings

The area of the visible disk, the area of the ansae (visible rings not overlapping the disk), and the area of overlap (visible rings overlapping the disk) were analytically determined to account for the thermal emission from the rings. These parameters were available in the ephemeris.

Matthews, S.↗
NASA NTRS1977

Elastic distortion of flanged inner ring of high-speed cylindrical roller bearing

The elastic distortion of the inner ring of an experimental roller bearing is investigated analytically. The geometry of the experimental bearing is unusually complex, and for this reason a bearing with an axially symmetric inner ring is also analyzed. Only the inner ring and shaft are considered using a two dimensional finite element program that can accommodate interference between these components. The results suggest that the elastic distortions are modest in relation to the design clearances associated with the experimental bearing. The variation of the radial deflection of the raceway may, however, be significant in some circumstances.

Taylor, C. M.↗
NASA NTRS1976

Explorer 45 observations of the proton ring current

Explorer 45 satellite data on the stormtime proton ring current are reported and analyzed. Storm-associated variations of equatorially mirroring protons, interactions between the ring current and the plasmapause, and storm recovery phase behavior are discussed. Pitch-angle distributions are plotted as a function of proton energy and radial distance, the structure implying domination of pitch-angle diffusion of ring-current protons in the plasmapause region by resonant interactions with ion cyclotron waves during storm recovery. The anisotropic precipitation in the plasmapause region and the more poleward isotropic precipitation observed at low altitudes outside the plasmapause are compared and distinguished.

Lyons, L. R.↗
NASA NTRS1977

Orbital changes of the gaseous ring around Be stars

In order to understand the seemingly erratic V/R variations and radial velocity curves of emission edges and central absorption of some Be stars, we have advanced, for the changes of structure of the gaseous ring around these stars, a theory that is based on the interaction between the existing ring and the newly ejected matter from the star. It shows that the structural change of the ring is completely controlled by the angular-momentum input factor and the dissipation factor. In light of this understanding, we have gone on to interpret the observed results of Beta-1 Mon and Pi Aqr.

Huang, S.-S.↗
NASA NTRS1977

Rotor burst protection program: Experimentation to provide guidelines for the design of turbine rotor burst fragment containment rings

Empirical guidelines for the design of minimum weight turbine rotor disk fragment containment rings made from a monolithic metal were generated by experimentally establishing the relationship between a variable that provides a measure of containment ring capability and several other variables that both characterized the configurational aspects of the rotor fragments and containment ring, and had been found from exploratory testing to have had significant influence on the containment process. Test methodology and data analysis techniques are described. Results are presented in graphs and tables.

Mangano, G. J.↗
NASA NTRS1977

Quantitative analysis of the Dermott-Gold theory for Uranus's rings

A summary is presented of an investigation which supplements the largely qualitative analysis conducted by Dermott and Gold (1977). Dermott and Gold have attempted to explain the locations of Uranus's rings in terms of resonances between ring particles and pairs of satellites. An equation of motion, analogous to that of a pendulum, is derived, taking into account a study by Wilkens (1933) of possible three-body resonances involving one minor and two major planets. Dermott and Gold had concluded that the observed pattern is probably due primarily to the effect of Ariel-Titania and Ariel-Oberon pairs. However, on the basis of the values derived in the reported investigation it is seen that Miranda plays the key role rather than Ariel, in spite of the small mass of the former. It is concluded that a decisive test of the Dermott-Gold theory has to await further observational details concerning the Uranus's rings.

Aksnes, K.↗
NASA NTRS1978

Orbital changes of the gaseous ring around Be stars. II - Apsidal motion and slow drift of the orbital elements

It is shown that the observed data about the apsidal motion of gaseous rings around some Be stars, like Beta(1) Mon and Pi Aqr, cannot be explained solely by the influence of the equatorial bulge. This fact has prompted the development of a theory of apsidal motion and slow drift of orbital elements that is based on the mixing of slowly escaping gases from the central star with gases in the emission ring around it. Thus, the basic physical idea in this paper follows closely what has been advanced in the first paper of this series but the mathematical treatment has been broadened in order to deal with the actual orbits, instead of osculating orbits, of particles in the ring. In accordance with this theory, it is believed that in cases where no mixing of gases takes place, the apsidal motion is controlled solely by the equatorial bulge. But in cases where mixing takes place, the apsidal motion depends upon the manner of gas mixing as well.

Huang, S.-S.↗
NASA NTRS1978

Saturn's rings: Particle composition and size distribution as constrained by microwave observations. I - Radar observations

The radar backscattering characteristics of compositional and structural models of Saturn's rings are calculated and compared with observations of the absolute value, wavelength dependence, and degree of depolarization of the rings' radar cross section (reflectivity). The doubling method is used to calculate reflectivities for systems that are many particles thick using optical depths derived from observations at visible wavelengths. If the rings are many particles thick, irregular centimeter- to meter-sized particles composed primarily of water ice attain sufficiently high albedos and scattering efficiencies to explain the radar observations. In that case, the wavelength independence of radar reflectivity implies the existence of a broad particle size distribution; a narrower size distribution is also a possibility. Particles of primarily silicate composition are ruled out by the radar observations. Purely metallic particles may not be ruled out on the basis of existing radar observations. A monolayer of very large ice 'particles' that exhibit multiple internal scattering may not yet be ruled out.

Cuzzi, J. N.↗
NASA NTRS1978

The formation of the Cassini division in Saturn's rings

An explanation for the size and location of the Cassini division in Saturn's rings is proposed. The explanation is based on the collective response of the particles in the ring to the resonant forcing by Mimas. An upper limit is calculated for the width of the gap that could be opened at a resonance. In addition, an estimate is obtained regarding the damping of the density waves by viscous and nonlinear effects. A picture is presented of the development of a gap. The results are compared with the observed properties of the divisions in Saturn's rings. The exact position of the inner edge of the Cassini division is difficult to predict, because the 2:1 resonance lies very near several weaker resonances (4:2 and 6:3 with Mimas, 4:1 with Tethys). However, the edge should lie near 17 seconds, and this is consistent with ground based observations.

Goldreich, P.↗
NASA NTRS1978

Amorphous ice on Saturnian rings and on icy satellites - Its formation, stability, and observability

Saturnian rings and icy satellites may be covered with amorphous rather than crystalline ice. Its likely source is water molecules sputtered by particles in the radiation belts, it may be stable, and its presence could be deduced from the rate of temperature drop in a shadow. Observation of this effect is, however, difficult, especially for the rings. A possible relation to the brightness anisotropy of ring A is pointed out.

Smoluchowski, R.↗
NASA NTRS1980

Improved piston rings for a stirling engine

Cast-iron piston rings coated with commercially-available antifriction materials improves cylinder life of high-performance Stirling engine. Ring is efficient heat conductor between piston and cylinder. Device has low thermal expansion which maintains minimum gap in ring, good radial force characteristics, and essentially indefinite life.

Mcdougal, A. R.↗