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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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NASA NTRS1982

Comments on the gamma-ray burst catalog of Mazets et al. /1981a/

A correlation has been discovered between the Venera spacecraft locations and the gamma-ray burst positions reported in the KONUS catalog (Mazets et al., 1981a). The reason for the correlation is not clear, but it could be due to spatial selection effects and/or large localization errors for weak or soft bursts. Whatever the cause, it seems likely that this systematic bias might significantly affect catalog results pertaining to gamma burst locations, intensity distributions, and spectra. For example, it can explain why the KONUS galactic latitude distribution is peaked significantly south of the galactic equator. Apparent discrepanices between the KONUS and Los Alamos gamma burst data bases are noted.

Laros, J. G.↗
NASA NTRS1983

Electron velocity distributions near the earth's bow shock

New information is presented on the general characteristics of electron distribution functions upstream, within, and downstream of the earth's bow shock, thereby providing new insights into the instabilities in collisionless shocks. The results presented are from a survey of electron velocity distributions measured near the earth's bow shock between October 1977 and December 1978 using the Los Alamos/Garching plasma instrumentation aboard ISEE 2. A wide variety of distribution shapes is found within the different plasma regions in close proximity to the bow shock. It is found that these shapes can be classified into general types that are characteristic of three different plasma regions, namely the upstream region or electron foreshock, the shock proper where most of the heating occurs, and the downstream region or the magnetosheath. Evidence is provided that field-aligned, rather than cross-field, instabilities are the major source of electron dissipation in the earth's bow shock.

Feldman, W. C.↗
NASA NTRS1982

Evidence for specularly reflected ions upstream from the quasi-parallel bow shock

Ion velocity distributions in the form of bunches of gyrating particles traveling along helical paths have been observed moving sunward immediately upstream from quasi-parallel parts of the earth's bow shock using Los Alamos/Garching instruments on ISEE-1 and -2. These distributions have characteristics which indicate that they are produced by the nearly specular reflection at the shock of a portion of the incident solar wind ions. In particular, the guiding center motion and the gyrospeeds of the gyrating ions are quantitatively consistent with simple geometrical considerations for specular reflection. These considerations reveal that specularly reflected ions can escape upstream when the angle between the upstream magnetic field and the local shock normal is less than 45 deg but not when the angle is greater than 45 deg. These upstream gyrating ions are an important signature of one of the processes by which solar wind streaming energy is dissipated into other forms of energy at the shock.

Gosling, J. T.↗
NASA NTRS1982

A basic code for the prediction of transient three-dimensional turbulent flowfields

A primitive pressure-velocity finite difference code has been developed to predict transient three-dimensional turbulent flow. The code is a simplified yet effective prediction procedure for use by persons with little experience in computational fluid dynamics, and into which user-oriented complexities can easily be added. The method is based on the transient two-dimensional Los Alamos SOLA prediction technique for laminar flows. Turbulence is simulated by means of a two-equation turbulence model; species diffusion and buoyancy are also included. Two applications of the code are presented to local destratification near the release structure of a reservoir and to the deflection of a jet entering normally into a uniform cross-flow. Predicted results exhibit good agreement with experimental data, showing that a useful characterization of fully three-dimensional flows is now available.

Busnaina, A. A.↗
NASA NTRS1982

Urban land use classification using synthetic aperture radar

In the cases of such land uses as the commercial and industrial, the incorporation of microwave data to that available from the visible and near visible regions may increase classification accuracy, provided that the limitations inherent in radar data are taken into consideration. Attention is presently given to several approaches to the use of radar data in land use classification of urban and near urban areas, with emphasis on L-band horizontal transmit and horizontal receive data available from Seasat-A. The Los Angeles, CA metropolitan area provides the geographic focus for this study.

Bryan, M. L.↗
NASA NTRS1983

Urban land use classification using synthetic aperture radar

Several approaches to the use of radar imagery for land use classification of urban and near-urban areas are presented. The use of L band, horizontal transmit, and horizontal receive data is emphasized because of their general availability. For urban area studies using imaging radar, the effects of processing in an off-zero Doppler or squint mode, of the presence of large diffuse scatters, and of the possibility of height measurements are discussed. Data from the Los Angeles area are illustratively used.

Bryan, M. L.↗
NASA NTRS1983

Spatial variation of iron abundance in the high speed solar wind, 1972 to 1976

The Fe/H ratios in the peaks of high speed streams (HSS) during the decline of Solar Cycle 20 and the following minimum (October 1972-December 1976) were analyzed. The response of the 50-200 keV ion channel of the APL/JHU energetic particle experiment (EPE) on IMP-7 and 8 to solar wind iron ions at high solar wind speeds and Fe measurements were compared with solar wind H and He parameters from the Los Alamos National Laboratory (LANL) instruments on the same spacecraft. In general, the Fe distribution parameters (bulk velocity, flow direction, temperature) are found to be similar to the LANL He parameters. Although the average Fe/H ratio in many steady HSS peaks agrees within observational uncertainties with the nominal coronal ratio of 4.7 x 10(-5), abundance variations of a factor of up to 6 are obtained across a given coronal-hole associated HSS. Over the period 1973-1976, a steady decrease in the average quiet-time Fe/H ratio by a factor of about 4 is measured on both IMP-7 and 8.

Mitchell, D. G.↗
NASA NTRS1982

Earth strain measurements with the transportable laser ranging system: Field techniques and planning

The potential of the transportable laser ranging system for monitoring the ground deformation around satellite ranging stations and other geodetic control points was examined with emphasis on testing the usefulness of the relative alteration technique. The temporal variation of the ratio of the length of each survey line to the mean length of all survey lines in a given area is directly related to the mean shear strain rate for the area. The data from a series of experimental measurements taken over the Los Angeles basin from a TLRS station at Mt. Wilson show that such ratios can be determined to an accuracy of one part in 10 million with a measurement program lasting for three days and without using any corrections for variations in atmospheric conditions. A numerical experiment using a set of hypothetical data indicates that reasonable estimates of the present shear strain rate and the direction of the principal axes in southern California can be deduced from such measurements over an interval of one to two years.

Nakamura, Y.↗
NASA NTRS1983

Solar wind iron abundance variations at speeds greater than 600 km/s, 1972-1976

An analysis has been conducted of the Fe/H ratios in the peaks of high-speed streams during the decline of solar cycle 20 and the following minimum (October 1972-December 1976). The response of the 50- to 200-keV ion channel of The Johns Hopkins University Applied Physics Laboratory energetic particle experiments (EPE) on IMP 7 and 8, which is (in the absence of energetic ions) dominated by solar wind iron ions at high solar wind speeds (V approximately equal to or greater than 600 km/s) as inferred from calibrations of flight spare detectors. The conducted Fe measurements have been compared with solar wind H and He parameters from the Los Alamos National Laboratory instruments on the same spacecraft. In general, the Fe distribution parameters (bulk velocity, flow direction, temperature) are found to be similar to the He parameters. Although the average Fe/H ratios found in the peaks of many steady high-speed streams agree within observational uncertainties with the nominal coronal ratio of 4.7 x 10 to the -5th, abundance variations of a factor of up to 6 are obtained across a given coronal-hole associated high-speed stream. There are, as well, a factor of 2 variations between stream-averaged abundances for recurrent high-speed streams emanating from different coronal holes occurring on the sun on the same solar rotation. Flare-related solar wind flows sometimes show Fe/H ratios enhanced by factors of 4-5 more than in coronal-hole associated, quiet-time streams, while in one case the Fe/H enhancement was still observable one rotation after the flare activity. Over the period 1973-1976, a steady decrease in the average quiet time Fe/H ratio by a factor of approximately 4 is measured on both IMP 7 and 8.

Mitchell, D. G.↗
NASA NTRS1983

Anisotropies and flows of suprathermal particles in the distant magnetotail - ISEE 3 observations

The ISEE-3 spacecraft has been transferred in 1982 into an earth orbit which brings the satellite close to the tailward Lagrangian point L2 at about 220 R(E) and thus allows exploration of the distant geomagnetic tail. An initial analysis of energetic proton measurements greater than 30 keV from the Max-Planck-Institut/University of Maryland sensor system on ISEE-3 is reported. It has been found that suprathermal protons are a persistent feature of the distant tail. Differential intensitites at 30 keV are essentially constant between the lunar distance and 220 R(E) and about one order of magnitude smaller than in the near earth, or greater than about 20 R(E), plasma sheet. Assuming that these protons are convected with the local plasma flow, it is possible to derive plasma velocities. During time periods where a comparison is possible, these velocities compare favourably well with the velocities derived from the Los Alamos National Laboratory plasma analyzer on board the same spacecraft. The appearance of the plasma sheet, as evidenced by the suprathermal particles, is rather bursty. Anisotropies are large, and predominantly tailward.

Scholer, M.↗
NASA NTRS1984

Salt-gradient Solar Ponds: Summary of US Department of Energy Sponsored Research

The solar pond research program conducted by the United States Department of Energy was discontinued after 1983. This document summarizes the results of the program, reviews the state of the art, and identifies the remaining outstanding issues. Solar ponds is a generic term but, in the context of this report, the term "solar pond" refers specifically to salt-gradient solar pond. Several small research solar ponds have been built and successfully tested. Procedures for filling the pond, maintaining the gradient, adjusting the zone boundaries, and extracting heat have been developed. Theories and models have also been developed and verified. The major remaining unknowns or issues involve the physical behavior of large ponds; i.e., wind mixing of the surface, lateral range or reach of horizontally injected fluids, ground thermal losses, and gradient zone boundary erosion caused by pumping fluid for heat extraction. These issues cannot be scaled and must be studied in a large outdoor solar pond. This report has been subdivided into three parts. Part One presents the results of the DOE research program. The major contributing institutions include Solar Energy Research Institute, Los Alamos National Laboratory, and Jet Propulsion Laboratory. Part Two presents related independent research conducted by universities. Part Three is a selected bibliography with abstracts.

R.L. French↗
NASA NTRS1985

Planetary Interior Modeling and Tectonic Implications

A technique is described for estimating spectral admittance functions using Pioneer Venus gravity and topography data. These admittance functions provide a convenient means to carry out systematic geophysical studies over much of the surface of Venus with a variety of interior density models. The admittance functions are calculated in the observation space of line-of-sight (LOS) gravity. Both closed and open system petrological models are considered for the Tharsis region of Mars. An analytic theory for isostatic compensation on one-plate planet is applied, including membrane stresses in the lithosphere, self gravitation, and rotational ellipticity. Crucial to this stress modeling and also to the petrological modeling is the observation that the earliest fracturing seen in the Tharsis region is associated with isostatic stresses. The radial fractures that extend far from Tharsis are associated with an additional and/or a completely different mechanism.

Phillips, R. J.↗
NASA NTRS1985

Liquid rocket combustor computer code development

The Advanced Rocket Injector/Combustor Code (ARICC) that has been developed to model the complete chemical/fluid/thermal processes occurring inside rocket combustion chambers are highlighted. The code, derived from the CONCHAS-SPRAY code originally developed at Los Alamos National Laboratory incorporates powerful features such as the ability to model complex injector combustion chamber geometries, Lagrangian tracking of droplets, full chemical equilibrium and kinetic reactions for multiple species, a fractional volume of fluid (VOF) description of liquid jet injection in addition to the gaseous phase fluid dynamics, and turbulent mass, energy, and momentum transport. Atomization and droplet dynamic models from earlier generation codes are transplated into the present code. Currently, ARICC is specialized for liquid oxygen/hydrogen propellants, although other fuel/oxidizer pairs can be easily substituted.

Liang, P. Y.↗
NASA NTRS1984

Millstone Hill radar: Capabilities for S/T observations

During the past several years, the 440-MHz radar at Millstone Hill has been modified to detect coherent echoes from clear-air turbulence in the stratosphere/troposphere (S/T) over the altitude range 4-25 km. Two distinct modes of data acquisition have been developed, and data reduction programs have been completed for one of these modes. This mode (I-mode) transmits a 10 microsec (1.5 km) pulse on the fully steerable antenna. Typically, the antenna is set at a low elevation angle (e.g., 15 deg.) to reduce the altitude resolution to approximately 1 km., and power spectra are collected at some 40 range gates. The antenna may be scanned in azimuth to obtain the total wind vector, held fixed to monitor wave motion, or scanned in elevation to monitor the horizontal extent of the turbulent activity. This steerability gives Millstone a flexible system to focus on localized events, such as lee waves or convective storms. An additional advantage at low elevations is the relatively large Doppler shift of the signal, since the LOS velocity contains a large component of the horizontal velocity. This shift separates the turbulence signal sufficiently far from the ground clutter to allow the spectral moments to be readily inferred. Some 500 hours of S/T I-mode data have been reduced to geophysical parameters, and reside on a data base at Millstone Hill.

Loriot, G. B.↗
NASA NTRS1984

Potentials for change detection using Seasat synthetic aperture radar data

The use of synthetic aperture radar (SAR) images for detecting change on the earth's surface is highly dependent on target orientation, azimuth angle, and sensor depression angle. SAR data can be used for change detection when consistency is maintained in radar wavelength, polarization, azimuth directions, and off-nadir depression angle. The interaction of these parameters and the imaged surface for change detection are shown in examples drawn from (1) Los Angeles, CA, (2) southern Florida, (3) Imperial Valley, CA, (4) a desert region west of Tucson, AZ, and (5) western Kansas. SAR imagery is used to emphasize the geometric form, and roughness, of the earth's surface. As changes in the roughness of the surface occur over time, temporal SAR images will indicate those differences. Several guidelines for change detection studies using imaging radar are derived from the examples.

Bryan, M. L.↗
NASA NTRS1985

Activated recombinative desorption: A potential component in mechanisms of spacecraft glow

The concept of activated recombination of atomic species on surfaces can explain the production of vibrationally and translationally excited desorbed molecular species. Equilibrium statistical mechanics predicts that the molecular quantum state distributions of desorbing molecules is a function of surface temperature only when the adsorption probability is unity and independent of initial collision conditions. In most cases, the adsorption probability is dependent upon initial conditions such as collision energy or internal quantum state distribution of impinging molecules. From detailed balance, such dynamical behavior is reflected in the internal quantum state distribution of the desorbing molecule. This concept, activated recombinative desorption, may offer a common thread in proposed mechanisms of spacecraft glow. Using molecular beam techniques and equipment available at Los Alamos, which includes a high translational energy 0-atom beam source, mass spectrometric detection of desorbed species, chemiluminescence/laser induced fluorescence detection of electronic and vibrationally excited reaction products, and Auger detection of surface adsorbed reaction products, a fundamental study of the gas surface chemistry underlying the glow process is proposed.

Cross, J. B.↗
NASA NTRS1985

SSME fuel preburner phase 1/phase 2+ comparison

An analytical comparison of the predicted combustion flowfields for the Phase 1 and Phase 2+ fuel preburner configurations using an advanced CFD combustion code is currently underway at Rocketdyne. The Phase 2+ injector has a modified element design. The redesigned element provides for improved atomization through a shift in the injector element/face bleed flow split while maintaining an acceptable pressure drop. Cold-flow tests of the new design have been encouraging. As a complement to those tests, the Advanced Rocket Injector Combustor Code (ARICC) was selected to conduct a detailed combustion flowfield simulation. ARICC models two-dimensional (or axisymmetric), transient, turbulent, two-phase mixing and combustion flowfields. It is derived from a member of the Los Alamos ICEd-ALE family of codes. Unique features of ARICC include explicit representation of the coaxial LOX jet and hydrogen gas flows, distributed atomization processes, droplet breakup, and supercritical vaporation processes. Predictions of temperature and OH concentration profiles for the Phase 1 and Phase 2+ injector flowfields indicate a trend toward more uniform temperature distributions and shorter flame lengths with the Phase 2+ design.

Jensen, R. J.↗
NASA NTRS1986

Radio continuum emission from winds, chromospheres, and coronae of cool giants and supergiants

The results of a sensitive VLA radio survey of the single cool-wind giants and super giants stars, having spectral types in the range (G0-M5), are presented. The survey was carried out at 6 cm using the NRAO VLA. The results of the observations are discussed in the context of the various mechanisms which might be producing radio emission in the cool stars. One coronal giant was detected as well as six cool-wind giants in the range 2-6 cm at levels of 0.1-2 mJy. The six-cm emission of the coronal giant alpha Aurigae is shown to be optically thin having free-free emission from the corona of energy 10 to the 7th K. The 2-cm emission from alpha Aur also contains contribution of about 65 percent from the stellar disk of one or both stars. The radio emission from all other sources is explained as optically thick emission from stellar winds. The inferred ionized mass-los rates for the cool wind stars was about 10 to the 10th solar mass per year for MK III-type stars and 10 to the -9th solar mass per year for MK II type stars.

Drake, S. A.↗