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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 847 records · Page 47

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NASA NTRS1978

The D and E rings of Saturn

CCD observations of Saturn ring D, discovered by Guerin in 1969, confirm the existence of this inner ring and indicate that its surface brightness ranges from 0.03 (inner edge) to 0.05 (outer edge) relative to the maximum surface brightness of ring B. If ring D is composed of spherical, diffusely reflecting particles with average surface reflectivity equal to that of the particles in ring B, the average normal optical thickness of ring D is 0.02. Reanalysis of a photograph taken by Feibelman during the 1966 ring plane passage suggests a normal optical thickness for ring E between -1 million and 10 to the minus 7 power, depending upon the average reflectivity of the particles. No new observations of this outer ring will be possible until the earth passes through the Saturn ring plane in 1979-80.

Smith, B. A.↗

NASA NTRS1979

Observations of the Saturn D ring

Observations of Saturn at both large and small phase angles were obtained in the 890-nm methane band with a solid state charge coupled device (CCD). When model intensity profiles are convolved with appropriate point spread functions, intensity levels ranging from 5 to 3% of the maximum of ring B are required in the ring D region of the models to match the data, in substantial agreement with previous results obtained through photographic photometry. The normal optical thickness of the D ring is about 0.02 and seems to show the same phase function as the other rings. The division between the C and D ring was not observed, possibly due to the seeing limited image resolution.

Larson, S. M.↗

NASA NTRS1979

The Landsat-D Assessment System

The overall Landsat-D system is discussed with emphasis on the objectives, configuration, and capabilities of the Landsat-D Assessment System. This system is being developed to support investigations which demonstrate, evaluate, and assess the utility of Landsat-D data for a wide variety of earth observations applications.

Bracken, P. A.↗

NASA NTRS1982

Tests and analysis of a vented D thrust deflecting nozzle on a turbofan engine

The objectives were to: obtain nozzle performance characteristics in and out of ground effects; demonstrate the compatibility of the nozzle with a turbofan engine; obtain pressure and temperature distributions on the surface of the D vented nozzle; and establish a correlation of the nozzle performance between small scale and large scale models. The test nozzle was a boilerplate model of the MCAIR D vented nozzle configured for operation with a General Electric YTF-34-F5 turbofan engine. The nozzle was configured to provide: a thrust vectoring range of 0 to 115 deg; a yaw vectoring range of 0 to 10 deg; variable nozzle area control; and variable spacing between the core exit and nozzle entrance station. Compatibility between the YTF-34-T5 turbofan engine and the D vented nozzle was demonstrated. Velocity coefficients of 0.96 and greater were obtained for 90 deg of thrust vectoring. The nozzle walls remained cool during all test conditions.

Roseberg, E. W.↗

NASA NTRS1982

LANDSAT-D thermal analysis and design support

Detailed thermal models of the LANDSAT-D Earth Sensor Assembly Module (ESAM), the Dummy Thematic Mapper (DTM), and a small thermal model of the LANDSAT-D spacecraft for a heater analysis were developed. These models were used to develop and verify the thermal design of the ESAM and DTM, to evaluate the aeroheating effects on ESAM during launch and to evaluate the thermal response of the LANDSAT-D assuming the hard-line heaters failed on with the spacecraft in the Space Transportation System (STS) orbiter bay. Results of model applications are summarized.

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NASA NTRS1981

Ground test of a large scale 'D' vented thrust deflecting nozzle

Future V/STOL aircraft will require efficient techniques for changing the thrust vector from the vertical direction for VTOL operation to the horizontal direction for conventional flight. Most V/STOL concepts utilize thrust vectoring nozzles to provide this variation in the thrust vector direction. An experimental test program was initiated to demonstrate the capabilities of a large scale 'D' vented thrust deflecting system coupled with a high bypass ratio turbofan engine. Data were obtained for a 'D' vented nozzle mounted behind a YTF-34-F5 turbofan engine. Preliminary data are presented for a variety of test conditions. Attention is given to aspects of 'D' vented nozzle design, the test apparatus, engine-nozzle compatibility, exit area variation, longitudinal vectoring performance, nozzle temperature distribution, and large scale - small scale comparisons.

Rosenberg, E. W.↗

NASA NTRS1982

LANDSAT-D Investigations Workshop

Viewgraphs are presented which highlight LANDSAT-D project status and ground segment; early access TM processing; LANDSAT-D data acquisition and availability; LANDSAT-D performance characterization; MSS pre-NOAA characterization; MSS radiometric sensor performance (spectral information, absolute calibration, and ground processing); MSS geometric sensor performance; and MSS geometric processing and calibration.

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NASA NTRS1981

LANDSAT-D data format control book. Volume 5: (Payload)

The LANDSAT-D flight segment payload is the thematic mapper and the multispectral scanner. Narrative and visual descriptions of the LANDSAT-D payload data handling hardware and data flow paths from the sensing instruments through to the GSFC LANDSAT-D data management system are provided. Key subsystems are examined.

Andrew, H.↗

NASA NTRS1982

Landsat-D, about to be reality

The space and ground segments of the Landsat-D thematic mapper (TM) for remote sensing of a 185 km swath with 30 m resolution are described. Scanning the full earth once every 16 days from its 705 km sunsynchronous orbit, Landsat-D will relay its data on the ku-band through the TDRSS satellite to a ground station. The X-band will also be used to transmit data directly to foreign and domestic ground stations; the S-band will be reserved for MSS data only. Landsat-D comprises the multimission modular spacecraft and the instrument module, which features the MSS and TM, a wideband communication subsystem, a solar array, and an L-band global positioning system. Three computers on the ground provide a high degree of automation for reception, storage, retrieval, back-up, and transmission of data and commands. Additionally, a van is equipped with transportable equipment, including an antenna. Procedures followed for image generation from the MSS and TM are detailed, noting storage at Goddard until dispersal of tapes under the direction of the EROS data center.

Aepli, T. C.↗

NASA NTRS1982

Landsat-D thematic mapper simulator

The design and testing program for the airborne Landsat-D thematic-mapper simulator (TMS) is summarized. The TMS is intended to provide data similar enough to those expected from Landsat-D to facilitate the development of data-processing software. The design process comprised mainly modifications on the existing MSS-simulator fiber optics, dichroics, and detectors to provide 7-channel coverage of the 0.45-12.3-micron range at 60-deg angle of view, corresponding to a 418-element, 13.8-km-wide ground swath. The TMS is carried on a Lear 23 aircraft operating at 750 km/h and 12-m altitude and equipped with a 15.2-cm aerial mapping camera and a ground-updated inertial navigational system. Agricultural, forestry, and geological trial applications are reviewed, and some sample results are given. The significant improvements predicted for the Landsat-D thematic mapper (relative to the Landsat MSS) are seen as confirmed, with the possible exception of the 120-m-resolution version of channel 7.

Flanagan, G. F.↗

NASA NTRS1984

The PH-D proposal - A manned mission to Phobos and Deimos

The rationale for a manned mission to the satellites of Mars is discussed. The view has been expressed that NASA must define a major program to follow the Shuttle and to utilize it. However, such a program could not be initiated and proceed without public support, and to obtain this support, public interest would have to be excited. It is shown that, of a number of possible targets for manned exploration in the solar system, Mars appears to be the only possible candidate. Attention is given to a comparison of three Mars missions, a Mars 1984 mission, a manned landing on Mars surface, a manned landing on Phobos and Deimos (Ph-D project), putting men in Mars orbit, the capabilities of the Ph-D mission, a description of the spacecraft, a Ph-D project operations plan, and aspects of timing, technology, and costs.

Singer, S. F.↗

NASA NTRS1984

Partial Reflection D-region Electron Densities

The differential absorption technique of measuring electron densities as a function of height in the D region is discussed. In the basic experiment, pulses of medium or high frequency, usually at a fixed frequency (2 to MHz), are radiated upwards with known wave polarizatin (usually linear or circular) from a transmitter at ground level. Partial reflections, from ionospheric scatterers at heights below the E region, are received at the ground, and are resolved into two characteristic components, the ordinary (0) and extraordinary (E) modes whose amplitude ration A(x)/A(o) is then measured as a function of height, h. The heights of these are determined by delay times, the group retardation being minimal in the undisturbed D-region. The electronic system can be very simple. Power splitters and quadrature networks to separate the A(x) and A(o) components are commercially available at low prices and an A-D converter, height-gate system, and microcomputer allows the real-time calculation of mean amplitudes. The ratio of the coefficients of reflection of the two modes, as they originate at each reflection height is then calculable.

Manson, A. H.↗

NASA NTRS1984

Neutral Atmosphere Properties Determining D-region Electron Densities

The increasing discoveries of various manifestations of meteorological control of the D region ionization and the growth of techniques for its measurement provide a challenge to meteorologists to test their insight into middle atmosphere processes with the physical interpretation of D layer phenomena. Models for ion production due to photoionization of minor atmospheric nitric oxide by quasi-monochromatic solar Lyman-alpha radiation are presented. A ground based measuring technique using low frequency radio reflection heights is briefly described and an approach to the interpretation of data acquired by this method is discussed. It is shown that D region electron density variations can provide an efficient diagnostic tool for the detection of perturbations of the circulation state of the middle atmosphere.

Taubenheim, J.↗

NASA NTRS1985

Development of a global 3-D magnetohydrodynamic computational model for solar wind/cometary and planetary studies

Progress is reported in the development of a global, 3-D magnetohydrodynamic computational model to quantitatively describe the detailed continuum field and plasma interaction process of the solar wind with cometary and planetary magneto/ionopause shapes. Activities described include enhancements to the present Level 1 model, development of the 3-D gas dynamic flow field solvers for the Level 2 model, and continued development of the 3-D frozen magnetic field solver for the Level 2 model.

Stahara, S. S.↗

NASA NTRS1985

On the breakdown of asymptotic Poincare invariance in D = 3 Einstein gravity

It is shown through a series of calculations that neither momentum nor boosts are definable for finite energy solutions of Einstein gravity in D = 3. The contrast between the effects of Lorentz transformations on the corresponding metrics for D = 3 and D = 4 gravity is demonstrated, and some comparisons with the vector gauge treatment of the problem are offered.

Deser, S.↗

NASA NTRS1985

R and D limited partnerships (possible applications in advanced communications satellite technology experiment program)

Typical R&D limited partnership arrangements, advantages and disadvantages of R&D limited partnership (RDLPs) and antitrust and tax implications are described. A number of typical forms of RDLPs are described that may be applicable for use in stimulating R&D and experimental programs using the advanced communications technology satellite. The ultimate goal is to increase the rate of market penetration of goods and/or services based upon advanced satellite communications technology. The conditions necessary for these RDLP forms to be advantageous are outlined.

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NASA NTRS1987

Energy transfer of O(D-1) atoms in collision with O(P-3) atoms

Calculations are carried out of the elastic scattering and excitation exchange cross-sections in collisions of O(D-1) and O(P-3) atoms, which determine the degree of thermalization of the O(D-1) atoms produced by dissociative recombination in the thermosphere. The effective elastic scattering and excitation exchange cross-sections are calculated to be 1.55 x 10 to the -15th and 6.25 x 10 to the -16th sq cm, respectively, at a relative collision energy of 1.0 eV. The mutual diffusion coefficient between O(D-1) and O(P-3) atoms is also presented.

Yee, Jeng-Hwa↗

NASA NTRS1987

Theoretical D(0) for NH(X3Sigma-)

A value of 3.37 + or - 0.03 eV is recommended for the D(0) of the X3Sigma(-) state of NH. The value of 3.34 eV computed directly from CAS SCF/MRSD CI calculations in a (5s4p3d2f1g/4s3p2d) contracted Gaussian basis has been corrected for basis set incompleteness based on analogous calculations on CH and OH where D(0) is accurately known. Equivalent full CI calculations on the ground states of CH, NH and OH in a (4s3p2d/2s1p) basis provide strong support for the 0.03 eV extrapolation of the D(0) for NH.

Bauschlicher, Charles W., Jr.↗