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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Interplanetary stream magnetism - Kinematic effects

The particle density and the magnetic-field intensity and direction are calculated for volume elements of the solar wind as a function of the initial magnetic-field direction and the initial speed gradient. It is assumed that the velocity is constant and radial. These assumptions are approximately valid between about 0.1 and 1.0 AU for many streams. Time profiles of the particle density, field intensity, and velocity are calculated for corotating streams, neglecting effects of pressure gradients. The compression and rarefaction of the magnetic field depend sensitively on the initial field direction. By averaging over a typical stream, it is found that the average radial field intensity is inversely proportional to the square of the heliocentric distance, whereas the average intensity in the direction of the planets' motion does not vary in a simple way, consistent with deep space observations. Changes of field direction may be very large, depending on the initial angle; but when the initial angle at 0.1 AU is such that the base of the field line corotates with the sun, the spiral angle is the preferred direction at 1 AU. The theory is also applicable to nonstationary flows.

Burlaga, L. F.↗
NASA NTRS1975

An overview of NASA's remote sensing program

The present status of NASA's remote sensing program and its future plans are reviewed, and some investigations into the possible uses of remotely sensed data are briefly summarized. Landsat-1 photographs are presented to demonstrate how such data can be employed for monitoring and forecasting of agricultural production, for watershed management and flood control, and for mineral exploration. The performance of Landsat-2 and expectations for Landsat-C are evaluated. High-priority problems which should be the driving forces for designing space observation systems for the 1980's are outlined, including the problem of world food supply and the relationship between land use and climatic changes. The design of the modular Landsat-D spacecraft, which will fly a thematic mapper for agricultural observations, is described.

Thome, P. G.↗
NASA NTRS1977

The local complex of O and B stars. II - Kinematics

The observed space velocities of O-B5 stars lying within about 1 kpc of the sun are analyzed. Motions examined include local solar motion, differential galactic rotation, mean peculiar stellar velocities, and systematic stellar motions parallel and perpendicular to the galactic plane. Kinematical determinations of the Oort constant and the K term for stars previously classified as members of the Gould and galactic belts are found to confirm earlier results that the Gould belt (or at least its youngest component) comprises a local perturbation in the general galactic velocity field. It is shown that if the Gould belt is expanding as a unit, its expansion age must be about 70 million years. The analyses also indicate negligibly small translational motion of the Gould belt relative to the galactic belt and parallel to the galactic plane as well as an approximate 'seesaw' motion of the Gould belt about the Cassiopeia-Carina line in the galactic plane. The age of the Gould belt is inferred to be either 20 or 60 million years from the vertical motions, which would imply the existence of either one or two waves of star formation as the Gould belt passed through the galactic belt either once or twice.

Frogel, J. A.↗
NASA NTRS1978

NASA and the U.S. climate program - A problem in data management

NASA's contribution to the total data base for the National Climate Plan will be to produce climate data sets from its experimental space observing systems and to maximize the value of these data for climate analysis and prediction. Validated data sets will be provided to NOAA for inclusion into their overall diagnostic data base. NASA data management for the Climate Plan will involve: (1) cataloging and retrieval of large integrated and distributed data sets upon user demand, and (2) the storage equivalent of 100,000 digital data tapes. It will be the largest, most complex data system ever developed by NASA

Quann, J. J.↗
NASA NTRS1980

Study of the Solar Cycle from Space

The objectives of and benefits to be derived from a program of solar cycle research are discussed with emphasis on the role space observations will play in this venture. The strategy to be employed in the coming decade is considered as well as crucial missions, experiments, and the theoretical advances required.

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NASA NTRS1980

Radio physics of the sun; Proceedings of the Symposium, University of Maryland, College Park, Md., August 7-10, 1979

Papers are presented in the areas of the radio characteristics of the quiet sun and active regions, the centimeter, meter and decameter wavelength characteristics of solar bursts, space observations of low-frequency bursts, theoretical interpretations of solar active regions and bursts, joint radio, visual and X-ray observations of active regions and bursts, and the similarities of stellar radio characteristics to solar radio phenomena. Specific topics include the centimeter and millimeter wave characteristics of the quiet sun, radio fluctuations arising upon the transit of shock waves through the transition region, microwave, EUV and X-ray observations of active region loops and filaments, interferometric observations of 35-GHz radio bursts, emission mechanisms for radio bursts, the spatial structure of microwave bursts, observations of type III bursts, the statistics of type I bursts, and the numerical simulation of type III bursts. Attention is also given to the theory of type IV decimeter bursts, Voyager observations of type II and III bursts at kilometric wavelengths, radio and whitelight observations of coronal transients, and the possibility of obtaining radio observations of current sheets on the sun.

Kundu, M. R.↗
NASA NTRS1981

Astronomical imaging investigations for Shuttle and Spacelab missions

General objectives of space astronomical imagery are briefly examined, taking into account the improved angular resolution achievable in space observations, the utilization of an accessibility of the far ultraviolet spectral range for an easier detection and more accurate measurement of very hot stars, the determination of the structure and evolution of galaxies, and the determination of the cosmic distance scale. Attention is given to the Ultraviolet Imaging Telescope, the Spacelab Wide Angle Telescope, and the Starlab UV/optical telescope facility. It is pointed out that Starlab is envisioned as a multi-instrument, multi-purpose astronomical facility based on a near-diffraction-limited Ritchey-Chretien telescope of about 1 meter aperture and f/15 focal ratio. These resolutions are a factor of 10 better than typically achieved with ground-based telescopes.

Carruthers, G. R.↗
NASA NTRS1982

U.S. mission plans for Spacelab

Mission configurations, instrumentation, and objectives for Spacelab sorties on board the Shuttle beginning in Sept. 1983 are reviewed. The first two flights will serve to verify the Spacelab systems and will be followed by operational status, including the fifth flight, which will be a reimbursible venture. Scientific investigations in the fields of atmospheric physics and environmental observation, space plasma physics, astronomy and solar physics, materials processing, and life sciences will be performed using the habitable long module, instrument pallets, and/or an instrument igloo mounted in the payload bay. Instrumentation, such as the imaging spectrometric observatory, which was developed in the U.S., will originate in either the U.S. or Europe. Details of the first four Spacelab flights are presented, noting that the OSS-3 through -7 missions will feature the first time that entire NASA payloads have returned to space.

Sander, M. J.↗
NASA NTRS1983

Spacelab mission 1 experiment descriptions, third edition

Experiments and facilities selected for flight on the first Spacelab mission are described. Chosen from responses to the Announcement of Opportunity for the Spacelab 1 mission, the experiments cover five broad areas of investigation: atmospheric physics and Earth observations; space plasma physics; astronomy and solar physics; material sciences and technology; and life sciences. The name of the principal investigator and country is listed for each experiment.

Craven, P. D.↗
NASA NTRS1983

STS-9: Orbital Workshop Spacelab to Fly on Ninth Shuttle Mission

The first non-astronants are discussed. Spacelab is described. Spacelab objectives, Spacelab 1 investigations, atmospheric physics and Earth observations, space plasma physics, solar physics and astronomy, material sciences and technology development, and life sciences are discussed.

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NASA NTRS1984

Spaceborne receivers: Basic principles

The underlying principles of operation of microwave receivers for space observations of planetary surfaces were examined. The design philosophy of the receiver as it is applied to operate functionally as an efficient receiving system, the principle of operation of the key components of the receiver, and the important differences among receiver types are explained. The operating performance and the sensitivity expectations for both the modulated and total power receiver configurations are outlined. The expressions are derived from first principles and are developed through the important intermediate stages to form practicle and easily applied equations. The transfer of thermodynamic energy from point to point within the receiver is illustrated. The language of microwave receivers is applied statistics.

Stacey, J. M.↗
NASA NTRS1986

Working Group on Circumstellar/Interstellar Relationships

Stars of various types are believed to be the main source of interstellar (IS) dust grans. The most important confirmed source is evolved giant and supergiant stars. Supernovae also contribute to the mass loss. The differences between circumstellar (CS) and IS dust were reviewed using the following topics: alteration of CS dust grains, size distribution, space observation of CS and IS dust, comparison of infrared spectra, isotopic signatures, Magellanic clouds and nearby galaxies, life cycles of dust grains, and physical and chemical data.

Glassgold, A. E.↗
NASA NTRS1984

Application of VISSR Atmospheric Sounder (VAS) data in weather analysis

A technique which analyzes irregularly spaced satellite data is described. An experiment with rawinsonde and VISSR Atmospheric Sounder (VAS) radiance measurements collected on March 6-7, 1982 is conducted to reveal the applicability of the technique. The rawinsonde data are analyzed on a 16 x 12 grid using the two pass analysis scheme of Barnes (1973). A scheme similar to the Barnes (1973) procedure is employed to produce gridded analysis of VAS data over a 200 x 15000 km region in central part of the U.S. The use of a correction pass on the initial gridded field is described; the technique is extremely effective on uniformly spaced observations. The incorporation of the limited fine mesh model to the scheme to analyze data in sparse and cloudy regions is examined. A comparison of rawinsonde data with VAS data is provided. The technique proves effective for studying cloudy and sparse areas with VAS data and produces a four-dimensional data set with significant mesoscale structure.

Jedlovec, G. J.↗
NASA NTRS1985

A note on finite-dimensional estimators for infinite-dimensional systems

In this note two theorems are proved regarding finite-dimensional estimators for infinite-dimensional systems. The first concerns the finite dimensionality of the model and the second concerns the finite dimensionality of the observation space. The analysis applies to very general systems, but appears to be most useful for the estimation of static systems from point sensing.

Milman, M. H.↗
NASA NTRS1986

Liquid helium cooled Fabry-Perot spectrometers

An account is given of two successful efforts to construct cryogenic Fabry-Perot interferometers that are sufficiently compact and stable for such harsh conditions as those of balloon or space observations, as well as ground-based ones. Attention is given to the design features and performance of a Fabry-Perot interferometer incorporating an electromagnet actuator, the ISAS interferometer, a Fabry-Perot spectrometer with superconducting actuators, and the University of Arizona interferometer.

Okuda, H.↗
NASA NTRS1987

Space-Based Remote Sensing of the Earth: A Report to the Congress

The commercialization of the LANDSAT Satellites, remote sensing research and development as applied to the Earth and its atmosphere as studied by NASA and NOAA is presented. Major gaps in the knowledge of the Earth and its atmosphere are identified and a series of space based measurement objectives are derived. The near-term space observations programs of the United States and other countries are detailed. The start is presented of the planning process to develop an integrated national program for research and development in Earth remote sensing for the remainder of this century and the many existing and proposed satellite and sensor systems that the program may include are described.

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NASA NTRS1988

Evolutionary period changes in the rapidly oscillating Ap stars

Preliminary computations of the asymptotic p-mode frequency spacings, and their time derivatives, are presented for a grid of evolutionary models of the rapidly oscillating Ap ('roAp') stars. It is shown how the frequency spacings depend on stellar mass, metallicity, and evolutionary stage. The frequency spacings observed in two of the roAp stars indicate that they either are main-sequence objects or have evolved off of the main sequence, depending on how the pulsation spectrum is interpreted. A way to remove this ambiguity is suggested: secular evolutionary changes in the pulsation frequencies may be measurable if the roAp stars have evolved off of the main sequence. In principle, this determination may be made for the roAp star HR 1217 with existing data.

Heller, Clayton H.↗
NASA NTRS1988

A postencounter view of comets

Ground-based and space observations of Comet Halley during its 1986 perihelion passage are reviewed, with an emphasis on their implications for theoretical models. Consideration is given to the shape, surface morphology, and composition of the comet nucleus; the shape, dynamics, and composition of the dust tail; neutral and ionic gas species in the head and plasma tail; and the comet/solar-wind interaction. Extensive diagrams, graphs, and sample images are provided, and the potential value of the new kinds of data to be obtained with the NASA Comet-Rendezvous/Asteroid-Flyby spacecraft is discussed.

Mendis, D. A.↗