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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

The physical properties of the Jovian atmosphere inferred from eclipses of the Galilean satellites. II - 1971 apparition.

Further simultaneous two-color photoelectric photometry of Ganymede was carried out at blue (4500 A) and yellow (5790 A) wavelengths during its eclipse by Jupiter on Mar. 10, 1971. In both colors, the shape of the ingress light curve was again reliably determined for extinctions up to 9 mag. Neither curve showed any evidence of a refraction tail. The observations have been interpreted in terms of the local optical transmission properties of the Jovian atmosphere. At gas number densities of about 5 x 10 to the 18th power per cu cm the maximum photon scattering mean free path at visual wavelengths was 47 km atm. Evidence indicates that neither a simple reflecting-layer model or a semiinfinite homogeneous scattering model provides an adequate physical description of the atmosphere.

Price, M. J.↗
NASA NTRS1972

Activities conducted during the definition phase of the outer planets missions program

The activities are described of the Meteoroid Science Team for the definition phase of the outer planet missions. Studies reported include: (1) combined zodiacal experiment for the Grand Tour Missions of the outer planets, (2) optical transmission of a honeycomb panel and its effectiveness as a particle impact surface, (3) element identification data from the combined zodiacal OPGT experiment and (4) development of lightweight thermally stable mirrors.

Source record↗
NASA NTRS1972

Investigation of gaseous nuclear rocket technology

The experimental and theoretical investigations conducted during the period from September 1969 through September 1972 are reported which were directed toward obtaining information necessary to determine the feasibility of the full-scale nuclear light bulb engine, and of small-scale nuclear tests involving fissioning uranium plasmas in a unit cell installed in a driver reactor, such as the Nuclear Furnace. Emphasis was placed on development of RF simulations of conditions expected in nuclear tests in the Nuclear Furnace. The work included investigations of the following: (1) the fluid mechanics and containment characteristics of one-component and two-component vortex flows, both unheated and RF-induction heated; (2) heating of particle-seeded streams by thermal radiation from a dc arc to simulate propellant heating; (3) condensation and separation phenomena for metal-vapor/heated-gas mixtures to provide information for conceptual designs of components of fuel exhaust and recycle systems; (4) the characteristics of the radiant energy spectrum emitted from the fuel region, with emphasis on definition of fuel and buffer-gas region seed systems to reduce the ultraviolet radiation emitted from the nuclear fuel; and (5) the effects of nuclear radiation on the optical transmission characteristics of transparent materials.

Kendall, J. S.↗
NASA NTRS1973

Crop identification using ERTS imagery

Digital analysis of August 15 ERTS-I imagery for southeastern South Dakota was performed to determine the feasibility of conducting crop surveys from satellites. Selected areas of bands 4, 5, 6, and 7 positive transparencies were converted to digital form utilizing Signal Analysis and Dissemination Equipment (SADE). The optical transmission values were printed out in a spatial format. Visual analysis of the printouts indicated that cultivated areas were readily distinguished from non-cultivated areas in all four bands. Bare soil was easily recognized in all four bands. Corn and soybeans, the two major crops in the area, were treated as separate classes rather than as a single class called row crops. Bands 6 and 7 provided good results in distinguishing between corn and soybeans.

Horton, M. L.↗
NASA NTRS1974

Study of optimum methods of optical communication

Abstracts are reported relating to the techniques used in the research concerning optical transmission of information. Communication through the turbulent atmosphere, quantum mechanics, and quantum communication theory are discussed along with the results.

Harger, R. O.↗
NASA NTRS1975

A Study of Synchronization Techniques for Optical Communication Systems

The study of synchronization techniques and related topics in the design of high data rate, deep space, optical communication systems was reported. Data cover: (1) effects of timing errors in narrow pulsed digital optical systems, (2) accuracy of microwave timing systems operating in low powered optical systems, (3) development of improved tracking systems for the optical channel and determination of their tracking performance, (4) development of usable photodetector mathematical models for application to analysis and performance design in communication receivers, and (5) study application of multi-level block encoding to optical transmission of digital data.

Gagliardi, R. M.↗
NASA NTRS1975

The effect of sunshine testing on terrestrial solar cell system components

Samples of FEP encapsulated silicon solar cells and various potential encapsulation or cover materials were subjected to accelerated and real time testing. By measuring changes in solar cell output or optical transmission as a function of exposure the durability of the samples was evaluated. Results are presented.

Forestieri, A. F.↗
NASA NTRS1975

The effect of sunshine testing on terrestrial solar cell system components

Samples of FEP-encapsulated silicon solar cells and various potential encapsulation or cover materials were subjected to both accelerated and real-time testing. The durability of the samples was determined by measuring changes in solar cell output or optical transmission as a function of exposure. The tests revealed some problem areas in the structural integrity of the materials, e.g., delamination and cracking in FEP. These problems were probably related to defects in fabrication. FEP and Aclar had the least transmission loss after accelerated exposure equivalents of 5 and 3 years, respectively.

Forestieri, A. F.↗
NASA NTRS1976

Space processing of chalcogenide glass

The manner in which the weightless, containerless nature of in-space processing can be successfully utilized to improve the quality of infrared transmitting chalcogenide glasses was investigated. The following conclusions were reached: (1) Laboratory experiments have established the techniques, processes and equipment necessary for the production of high purity chalcogenide glasses. (2) Processing techniques have been successfully adopted for Ge28Sb12Se60 glass in a 1-g environment. (3) The Ge28Sb12Se60 glasses that have been processed have optical transmission around 63% (5 mm thick). (4) Laboratory experiments have established that the use of precursor materials in powdered form increases the oxygen contamination of the processed glass. This indicates that high purity precursor materials in bar or pellet form should be used. (5) Modifications were made on the MSFC acoustic levitator in an attempt to improve levitation stability during long-time experiments. Room temperature experiments on As2S3 glasses and high temperature experiments on polystyrene were conducted.

Ali, M. A.↗
NASA NTRS1976

Spectrophotometry of Jupiter

Spectrophotometric maps of Jupiter were made between 24 and 27 (UT) November 1974 on the McMath Solar Telescope at Kitt Peak National Observatory. We report a comparison between observed scaled reflectivities of the Jovian North Tropical Zone and the North Equatorial Belt at System II longitudes between 195 and 205 degrees. The belt/zone reflectivity ratios between 430 and 740 nm are related to the optical transmission curves of the organic and/or sulfur polymers synthesized by Khare and Sagan in a simulated Jovian atmosphere.

Wamsteker, W.↗
NASA NTRS1977

Electrically-controlled variable-color optical filters

Optical transmission characteristics of birefringent element are changed by applying voltage to plate. Filters are used on sequential-color television cameras and in color displays. Filters are more convenient and less costly than mechanical color wheels and crystal-based filters.

Miller, A.↗
NASA NTRS1978

Acoustic holography: Problems associated with construction and reconstruction techniques

The implications of the difference between the inspecting and interrogating radiations are discussed. For real-time, distortionless, sound viewing, it is recommended that infrared radiation of wavelength comparable to the inspecting sound waves be used. The infrared images can be viewed with (IR visible) converter phosphors. The real-time display of the visible image of the acoustically-inspected object at low sound levels such as are used in medical diagnosis is evaluated. In this connection attention is drawn to the need for a phosphor screen which is such that its optical transmission at any point is directly related to the incident electron beam intensity at that point. Such a screen, coupled with an acoustical camera, can enable instantaneous sound wave reconstruction.

Singh, J. J.↗
NASA NTRS1978

Protection of solar collector materials from UV

Certain plastic films, such as KAPTON, are known to be stable with excellent long-term aging characteristics under intense uv radiation. Our recent measurements of the optical transmission spectra of KAPTON films show an absorption edge in the blue and are interpreted in terms of an electronic excitation mechanism. The application of this type of film as covering for solar collectors is discussed in regard to the protection this strong uv absorption offers to the materials underneath.

Castle, J. G., Jr.↗
NASA NTRS1980

High sensitivity pulse-counting mass spectrometer system for noble gas analysis

A pulse-counting mass spectrometer is described which is comprised of a new ion source of cylindrical geometry, with exceptional optical properties (the Baur source), a dual focal plane externally adjustable collector slits, and a 17-stage Allen-type electron multiplier, all housed in a metal 21 cm radius, 90 deg magnetic sector flight tube. Mass discrimination of the instrument is less than 1 per mil per mass unit; the optical transmission is more than 90%; the source sensitivity (Faraday collection) is 4 ma/torr at 250 micron emission; and the abundance sensitivity is 30,000.

Hohenberg, C. M.↗
NASA NTRS1981

SPS fiber optic link assessment

Fiber optic technology was tentatively selected in the SPS baseline design to transmit a stable phase reference throughout microwave array. Over a hundred thousand microwave modules are electronically steered by the phase reference signal to form the power beam at the ground receiving station. The initially selected IF distribution frequency of the phase reference signal was at 980 MHz or a submultiple of it. Fiber optics offers some significant advantages in view of the SPS application. Optical transmission is highly immune to EMI/RFI, which is expected to be severe when considering the low distribution power. In addition, there are savings in both mass, physical size, and potentially in cost.

Lindsay, T. O.↗
NASA NTRS1981

Far-infrared bandpass filters from cross-shaped grids

The optical transmission characteristics of electroformed metal grids with inductive and capacitive cross patterns have been investigated in the far-infrared spectral region. The transmission characteristics of one- and two-grid devices are represented by transmission line theory parameters. Results are used to suggest construction guidelines for two-grid bandpass filters.

Tomaselli, V. P.↗
NASA NTRS1980

SPS fiber optic link assessment

Fiber optic technology was selected in the SPS baseline design to transmit a stable phase reference throughout the microwave array. Over a hundred thousand microwave modules are electronically steered by the phase reference signal to form the power beam at the ground receiving station. The initially selected IF distribution frequency of the phase reference signal was set at 980 MHz or a submultiple of it. Fiber optics offers some significant advantages in view of the SPS application. Optical transmission is highly immume to EMI/RFI, which is expected to be severe when considering the low distribution power. In addition, there will be savings in both mass, physical size, and potentially in cost.

Lindsay, T. O.↗