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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Chemical nonequilibrium and viscous flow computation for conic aerobrake bodies

Three-dimensional analyses are presented for the viscous, reactive flow over a complete entry-body configuration with a wide-angle conic surface. The predictive method uses a split approach that solves iteratively the Navier-Stokes and the continuity equations of chemical species. The finite-difference formulation and the computational grid are adapted to the bow shock and the conformally mapped body such that the velocity components are in the computational spherical-polar space. Combinations of several conic forebody and afterbody configurations have been studied using wind-tunnel, Space Shuttle, and aerobraking orbital transfer vehicle (AOTV) entry conditions. The effects of the borebody bluntness and of finite-rate chemical reactions on the shock layer, the wall catalycity on the boundary layer, the shear-layer impingement on the afterbody, and the base-flow environment are discussed.

Li, C. P.↗
NASA NTRS1988

Virtual interface environment workstations

A head-mounted, wide-angle, stereoscopic display system controlled by operator position, voice and gesture has been developed at NASA's Ames Research Center for use as a multipurpose interface environment. This Virtual Interface Environment Workstation (VIEW) system provides a multisensory, interactive display environment in which a user can virtually explore a 360-degree synthesized or remotely sensed environment and can viscerally interact with its components. Primary applications of the system are in telerobotics, management of large-scale integrated information systems, and human factors research. System configuration, research scenarios, and research directions are described.

Fisher, S. S.↗
NASA NTRS1989

Neptune cloud structure at visible wavelengths

Digital images of Neptune showing cloud structure at visible wavelengths were obtained in July 1988. A discrete bright feature was detected both at 6190 A (a weak methane absorption band in the visible) and at 8900 A (a stronger methane band in the near infrared). The images also revealed that Neptune's southern pole was bright relative to planetary mid-latitudes at 6190 A but not 8900 A. The implications of these findings for atmospheric rotation and structure are discussed. The detection of discrete features at visible wavelengths is of special importance to the upcoming Voyager encounter with Neptune: the wide-angle camera has a 6190 A filter similar to that used for these observations.

Hammel, H. B.↗
NASA NTRS1990

Compact, Broadband Infrared Spectrometer

Large-aperture, wide-angle, broad-band infrared spectrometer compact and light in weight. Based on double-pass version of Schmidt optical system that acts as both collimator and camera. Because optical system contained in piece of solid glass, it is mechanically and thermally stable. System made of water-free fused silica to minimize absorption of infrared radiation. Although in principle made from single, solid piece, in practice made in two pieces cemented together. Fabrication easier and simpler if more cemented surfaces used so each optical surface grounded and polished like single lens element.

Page, Norman A.↗
NASA NTRS1990

Helmet-Mounted Visual Display For Flight Simulation

Helmet-mounted visual display system provides pilot with broad range of visual information for flight simulation. Offers nearly unlimited field of regard. Optical fibers transmit wide-angle images in response to motions of head. Two "pancake" lenses mounted on lightweight helmet. Cable of optical fibers carries images to each lens. "Light-valve" projectors deliver computer-generated binocular images to cables.

Cook, Anthony M.↗
NASA NTRS1990

KD2PO4 Polarization Modulator With Large Field Of View

Improved potassium dideuterium phosphate (KD2PO4) electro-optical linear-polarization modulator suitable for use with optical instruments having large (wide-angle) fields of view. Errors previously caused by convergence of light eliminated.

West, Edward A.↗
NASA NTRS1988

Mission Report on the Orbiter Camera Payload System (OCPS) Large Format Camera (LFC) and Attitude Reference System (ARS)

The Orbiter Camera Payload System (OCPS) is an integrated photographic system which is carried into earth orbit as a payload in the Space Transportation System (STS) Orbiter vehicle's cargo bay. The major component of the OCPS is a Large Format Camera (LFC), a precision wide-angle cartographic instrument that is capable of producing high resolution stereo photography of great geometric fidelity in multiple base-to-height (B/H) ratios. A secondary, supporting system to the LFC is the Attitude Reference System (ARS), which is a dual lens Stellar Camera Array (SCA) and camera support structure. The SCA is a 70-mm film system which is rigidly mounted to the LFC lens support structure and which, through the simultaneous acquisition of two star fields with each earth-viewing LFC frame, makes it possible to determine precisely the pointing of the LFC optical axis with reference to the earth nadir point. Other components complete the current OCPS configuration as a high precision cartographic data acquisition system. The primary design objective for the OCPS was to maximize system performance characteristics while maintaining a high level of reliability compatible with Shuttle launch conditions and the on-orbit environment. The full-up OCPS configuration was launched on a highly successful maiden voyage aboard the STS Orbiter vehicle Challenger on October 5, 1984, as a major payload aboard mission STS 41-G. This report documents the system design, the ground testing, the flight configuration, and an analysis of the results obtained during the Challenger mission STS 41-G.

Mollberg, Bernard H.↗
NASA NTRS1989

The eyes prefer real images

For better or worse, virtual imaging displays are with us in the form of narrow-angle combining-glass presentations, head-up displays (HUD), and head-mounted projections of wide-angle sensor-generated or computer-animated imagery (HMD). All military and civil aviation services and a large number of aerospace companies are involved in one way or another in a frantic competition to develop the best virtual imaging display system. The success or failure of major weapon systems hangs in the balance, and billions of dollars in potential business are at stake. Because of the degree to which national defense is committed to the perfection of virtual imaging displays, a brief consideration of their status, an investigation and analysis of their problems, and a search for realistic alternatives are long overdue.

Roscoe, Stanley N.↗
NASA NTRS1990

The radio properties of cD galaxies in Abell clusters. I - An X-ray selected sample

The radio and X-ray properties of a sample of 27 cD galaxies in rich clusters are presented. The radio data consist of 6 cm VLA maps at a resolution of 1-2 arcsec. The X-ray data consist of images and surface-brightness profiles from the Einstein IPC and derived quantities such as cooling times, mass-accretion rates, and thermal pressures from Arnaud (1988). These data are used to explore the relationship between X-ray cooling cores, and the power and morphology of the radio emission. It is found that 71 percent of the cD's with X-ray cooling cores are radio loud, whereas a smaller but still significant 23 percent of cD's without cooling cores are detected at 6 cm above 0.2 mJy. Among the radio galaxies in noncooling core clusters are luminous and extended wide-angle tails. There is a weak correlation between the mass-accretion rate and the radio power for cD's. There is also an interesting class of cooling core cluster (e.g., A2052) with small diameter, amorphous radio emission that may be the result of diffusion along radial magnetic fields set up in cooling inflows. Finally, the relationships between optical emission-line luminosity with radio power and mass-accretion rate are examined.

Burns, Jack O.↗
NASA NTRS1990

Polyamideimides containing carbonyl and ether connecting groups

Polyamidenimides were prepared from the reaction of trimellitic anhydride chloride with seven diamines containing carbonyl and ether groups between the aromatic rings. Several of these polyamideimides were semicrystalline as evidenced by wide-angle X-ray diffraction and differential scanning calorimetry. Glass transition temperatures ranged between 187 and 245 C, and crystalline transition temperatures ranged between 317 and 416 C. A series of copolyamideimides from a mixture of 1,3-bis(4-aminophenoxy 4-prime-benzoyl) benzene and 1,4-bis(4-aminophenoxy 4-prime-benzoyl)benzene were similarly prepared. These copolyamideimides were semicrystalline and formed tough, solvent resistant films with good tensile properties.

Havens, S. J.↗
NASA NTRS1990

Voyager disk-integrated photometry of Triton

Hapke's (1981) photometric model has been combined with a plane-parallel thin atmospheric haze model to describe Voyager whole-disk observations of Triton, in the violet, blue, and green wavelength bands, in order to obtain estimates of Triton's geometric albedo, phase integral, and Bond albedo. Phase angle coverage in these filters ranging from about 12 to 159 deg was obtained by combining narrow- and wide-angle camera images. An upturn in the data at the highest phase angles observed can be explained by including scattering in a thin atmospheric haze layer with optical depths systematically decreasing with wavelength from about 0.06 in the violet to 0.03 for the green filter data.

Hillier, J.↗
NASA NTRS1990

Implementation and integration of a counterbalanced CRT-based stereoscopic display for interactive viewpoint control in virtual environment applications

The NASA-Ames Counterbalanced CRT-based Stereoscopic Viewer (CCSV), which is being used as a viewing device for biomechanical CAD environments, is uniquely suited for applications in which the user frequently moves between desk work and virtual environment viewing, or in which high resolution views of the virtual environment are required, or in which the viewing device must be shared among collaborators in a group setting. The CCSV hardware encompasses a dual-CRT-based stereoscopic viewer with wide-angle optics, a video electronics box, a dedicated microprocessor system monitoring joint angles in the linkage, and a host computer interpreting sensor values and running the application which renders the right and left views for reader CRTs.

Mcdowall, I. E.↗
NASA NTRS1992

Hand/Eye Coordination For Fine Robotic Motion

Fine motions of robotic manipulator controlled with help of visual feedback by new method reducing position errors by order of magnitude. Robotic vision subsystem includes five cameras: three stationary ones providing wide-angle views of workspace and two mounted on wrist of auxiliary robot arm. Stereoscopic cameras on arm give close-up views of object and end effector. Cameras measure errors between commanded and actual positions and/or provide data for mapping between visual and manipulator-joint-angle coordinates.

Lokshin, Anatole M.↗
NASA NTRS1991

Imaging studies of comets

The Joint Observatory for Cometary Research's (JOCR) historical mission has been to provide understanding of large-scale interactions between bright comets and solar wind using wide-angle (Schmidt) imagery and spacecraft data; in this pursuit the JOCR has excelled. The 16 inch Newtonian/Cassegrain telescope was upgraded to permit filtered, narrow-field charge coupled device (CCD) imaging of both bright and faint comets. Thus, the goal of obtaining narrow-band imagery of the near-nuclear region of bright comets was added to JOCR's original mission with emphasis on ionization processes and total gas production. A 300 mm lens/CCD system exists with 3 degree field of view (FOV) which uses comet filters; this system bridges the gap between the wide-field (8 x 10 deg) Schmidt plates and the several-arcmin. field of the 16 inch telescope. JOCR is located under dark skies on South Baldy Mountain (el. 10,600 ft.) near Socorro, NM, and is one of the last truly dark sites in the continental U.S.

Niedner, Malcolm B., Jr.↗
NASA NTRS1992

Characterization of low thermal conductivity PAN-based carbon fibers

The microstructure and surface chemistry of eight low thermal conductivity (LTC) PAN-based carbon fibers were determined and compared with PAN-based fibers heat treated to higher temperatures. Based on wide-angle x ray diffraction, the LTC PAN fibers all appear to have a similar turbostratic structure with large 002 d-spacings, small crystallite sizes, and moderate preferred orientation. Limited small-angle x ray scattering (SAXS) results indicate that, with the exception of LTC fibers made by BASF, the LTC fibers do not have well developed pores. Transmission electron microscopy shows that the texture of the two LTC PAN-based fibers studied (Amoco T350/23X and /25X) consists of multiple sets of parallel, wavy, bent layers that interweave with each other forming a complex three dimensional network oriented randomly around the fiber axis. X ray photoelectron spectroscopy (XPS) analysis finds correlations between heat treated temperatures and the surface composition chemistry of the carbon fiber samples.

Katzman, Howard A.↗
NASA NTRS1992

Ka-band active MMIC subarray development

A 4 x 8 array consisting of two adjacent 4 x 4 MMIC subarray modules under development as part of a MMIC insertion program for the ACTS communication experiments is presented. The subarray features a high-density 'tile' configuration integrating 16 MMIC power amplifiers and 16 MMIC phase shifters. The radiating elements are cavity-backed, aperture coupled, linearly polarized microstrip patches arranged on a 4 x 4 square grid. Each module also incorporates a MMIC controller to set the phase shifts and to turn individual amplifiers 'on' or 'off'. The novel module construction technique is expected to establish a benchmark in Ka-band and higher-frequency array architectures. The hybrid integration approach used for the module can be replaced by multifunctional chips and multilayer distribution boards. The higher level of integration is to permit the dense grid spacing required for wide-angle scanning and reduced size, weight, and cost for the array.

Lee, Richard↗
NASA NTRS1992

Mars Observer camera

The Mars Observer camera (MOC) is a three-component system (one narrow-angle and two wide-angle cameras) designed to take high spatial resolution pictures of the surface of Mars and to obtain lower spatial resolution, synoptic coverage of the planet's surface and atmosphere. The cameras are based on the 'push broom' technique; that is, they do not take 'frames' but rather build pictures, one line at a time, as the spacecraft moves around the planet in its orbit. MOC is primarily a telescope for taking extremely high resolution pictures of selected locations on Mars. Using the narrow-angle camera, areas ranging from 2.8 km x 2.8 km to 2.8 km x 25.2 km (depending on available internal digital buffer memory) can be photographed at about 1.4 m/pixel. Additionally, lower-resolution pictures (to a lowest resolution of about 11 m/pixel) can be acquired by pixel averaging; these images can be much longer, ranging up to 2.8 x 500 km at 11 m/pixel. High-resolution data will be used to study sediments and sedimentary processes, polar processes and deposits, volcanism, and other geologic/geomorphic processes.

Malin, M. C.↗
NASA NTRS1992

Chemistry and properties of poly(arylene ether benzoxazole)s

Several new poly(arylene ether benzoxazole)s (PAEBs) were prepared by the nucleophilic displacement reaction of activated aromatic difluorides with two novel bis(hydroxyphenyl benzoxazole), using potassium carbonate. The 6F-containing PAEBs exhibited better solubility and higher Tgs than did the 6,6'-bis-(2-(4-hydroxyphenyl)benzoxazole)-derived polymers. Several of the 6,6'bis(2-(4-hydroxyphenyl)benzoxazole)-derived polymers exhibited crystallinity by DSC and wide-angle X-ray diffraction. Unorientated thin film properties of the 6F-containing PAEBs were comparable to those of other 6F-containing PAEBS that were previously reported. The chemistry and the physical and mechanical properties of the above polymers are discussed.

Smith, J. G., Jr.↗