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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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A brief summary of salient science results obtained from the Mariner 9 mission through June 1972 are presented. The data are presented in the form of photographs, line drawings and graphs. Emphasis is placed on the composition of the south polar cap, the surface of the satellites, and the presence of clouds in the atmosphere. The size and configuration of topographical features are compared with similar earth structures for reference.
An approach to an argon ion laser based on gasdynamic techniques is presented. Improvement in efficiency and power output are achieved by eliminating high heat rejection problems and plasma confinement of the seal-off conventional lasers. The process of producing population inversion between the same energy levels, as in the conventional argon ion laser, has been divided into two phases by separating each other from the processes of ionization and subsequent excitation. Line drawings and graphs are included to amplify the theoretical presentation.
The design and testing of vane sets and air-exchange inlet for the 40 x 80/80 x 120-ft wind tunnel at NASA Ames are reported. Boundary-layer analysis and 2D and 3D inviscid panel codes are employed in computer models of the system, and a 1/10-scale 2D facility and a 1/50-scale 3D model of the entire wind tunnel are used in experimental testing of the vane sets. The results are presented in graphs, photographs, drawings, and diagrams are discussed. Generally good agreement is found between the predicted and measured performance.
The design and testing of vane sets and air-exchange inlet for the 40 x 80/80 x 120-ft wind tunnel at NASA Ames are reported. Boundary-layer analysis and 2D and 3D inviscid panel codes are employed in computer models of the system, and a 1/10-scale 2D facility and a 1/50-scale 3D model of the entire wind tunnel are used in experimental testing of the vane sets. The results are presented in graphs, photographs, drawings, and diagrams and discussed. Generally good agreement is found between the predicted and measured performance.
The Pioneer 10 and 11 missions are surveyed and illustrated with drawings, maps, graphs, and diagrams, with an emphasis on their present exploration of the outer heliosphere. The main goals of this exploration are examined (search for the heliospheric boundary, measurement of galactic cosmic radiation, and search for a trans-Neptunian planet); the ten scientific instruments carried by each spacecraft are characterized; and the results obtained so far with regard to the solar wind and interplanetary magnetic field, cosmic rays, and asteroid belt, Jupiter, and Saturn are summarized.
Current theoretical models developed to explain the observational data (from spaceborne detectors) on gamma-ray bursters are summarized and illustrated with drawings, diagrams, graphs, and photographic images. Although the data are fragmentary and often flawed by instrument defects, models involving neutron stars with strong magnetic fields are generally favored, and it is assumed that most observed bursters lie within the Galaxy. The neutron-star origin of the bursts is suggested by their intensity and rapid variability (implying a very compact high-energy source) and the presence in some burster spectra of a line at 420 keV which is explained by the combination of electron-positron annihilation and gravitational reddening. Consideration is also given to optical flashes observed to occur about once per year in the direction of gamma bursters, and the need for further searches for lower-energy emissions from bursters is stressed.
A technique for performing accelerated stress tests of large-area thin a-Si solar cells is presented. A computer-controlled short-interval test system employing low-cost ac-powered ELH illumination and a simulated a-Si reference cell (seven individually bandpass-filtered zero-biased crystalline PIN photodiodes) calibrated to the response of an a-Si control cell is described and illustrated with flow diagrams, drawings, and graphs. Preliminary results indicate that while most tests of a program developed for c-Si cells are applicable to a-Si cells, spurious degradation may appear in a-Si cells tested at temperatures above 130 C.
Organizational and technological aspects of the operation by NASA and ESA of the IUE satellite observatory since its launch in 1978 are discussed. Topics addressed include the division of responsibilities among the ground stations, the IUE orbit and its evolution, the IUE spacecraft, normal operations (proposal selection and observation planning, shift handover, and spacecraft operations), and a typical observation (target identification and acquisition, telescope focus, spectrograph modes, camera operations, calibration, and data reduction). Consideration is given to constraints on IUE operation due to the sun-earth-moon configuration (eclipses), spacecraft power, radiation, temperature, and momentum-wheel speed; problems encountered with gyros, onboard computers, the fine sun sensor, and cameras; and the reliable high-efficiency overall performance of the IUE. Diagrams, drawings, and graphs are provided.
The Integrated Multidisciplinary Analysis Tool (IMAT), a computer software system developed at NASA Langley to analyze and simulate the dynamics of space-structure/control-system interactions, is described, and its application to the MAST problem (a 60-m truss with fundamental frequency less than 200 mHz and equipped with linear proof-mass actuators, to be deployed from the Space Shuttle as part of COFS-I flight experiment) is demonstrated. Particular attention is given to the IMAT procedures which facilitate the use of the MCS/NASTRAN code to recover physical results from time-domain state-space solutions obtained with an FEM control-design code. Diagrams, drawings, and graphs are provided.
The MFOX family of standardized fiber-optic communications modules developed for the USAF is described. The MFOX transceivers are designed to operate at wavelength 1.3 microns under severe environmental conditions; their compact subhybrid construction and flexible electronic interfaces permit multiple applications and mountings. The family comprises five performance levels: (1) 1-10,000-kb/s digital and (2) 0.2-50 Mb/s digital using LEDs, (3) up to 10-MHz-bandwidth analog using modulator/demodulators with level (2) transceivers, (4) 0.2-400-Mb/s digital and 70-MHz IF analog using multimode lasers, and (5) 200-1000-Mb/s digital using a single-mode laser; levels (4) and (5) are currently in the experimental stage. Drawings, diagrams, graphs, and tables of physical and optical specifications are provided.
The design and performance of a prototype power-conditioning system for use with large brushless dc motors on NASA space missions are discussed in detail and illustrated with extensive diagrams, drawings, and graphs. The 5-kW 8-phase parallel module evaluated here would be suitable for use in the Space Shuttle Orbiter cargo bay. A current-balancing magnetic assembly with low distributed inductance permits high-speed current switching from a low-voltage bus as well as current balancing between parallel MOSFETs.
A list is presented of the trade studies which were planned and the status to which they have been accomplished. Full descriptions are also given of the trade studies along with line drawings and graphs illustrating the studies.
The design concept of an unobscured-wide-field two-stage optical system based on a virtual triple Schmidt (VTS) configuration is presented. It is pointed out that the single large aperture and field-partitioning capability of two-stage systems can lower material and fabrication costs, making the VTS optics suitable for ground-based and space telescopes. The VTS design combines a Schmidt-camera first stage and a second stage comprising two back-to-back Schmidt systems as a 1:1 relay. Aspheric Schmidt correction is achieved at the relayed pupil location for all three systems. The effects of the separation between the error-producing surface and the aperture stop are discussed; the performance of the wavefront-correction system is analyzed; and extensive diagrams, drawings, and graphs of projected performance data are provided.
Theoretical and applications aspects of optoelectronic control for microwave devices are examined in an introduction for graduate engineering students and practicing engineers. The basic features of optical MMICs are reviewed, and chapters are devoted to laser diodes, electrooptic modulators, photodetectors, microwave fiber-optic links, optoelectronic switching and gating, optoelectronic microwave signal generation, an optoelectronic switch matrix, optoelectronic switching and modulation of oscillators, and optoelectronic injection-locking and tuning of oscillators. Extensive diagrams, drawings, and graphs are provided.
The optical system for the proposed Lyman/Far UV Spectroscopic Explorer (FUSE) orbiting observatory is described and illustrated with drawings and graphs of predicted performance. The system comprises (1) an FUV channel based on a 1.84-m-diameter Rowland circle spectrograph with five high-density modified ellipsiodal near-normal-incidence gratings and an array of four MAMA detectors; (2) an EUV channel with ellipsoidal mirror, planar varied-line-space grating, microchannel-plate array, and wedge-and-strip anode detector; (3) a 70-cm Wolter II glancing-incidence telescope; and (4) a CCD-detector fine-error sensor to provide accurate pointing (within 200 marcsec rms). The resolving powers of the spectrographs are 30,000 in the FUV and 300-600 (wavelength-dependent) in the EUV.
The Engineering Scripting Language (ESL) is a language designed to allow nonprogramming users to write Higher Order Language (HOL) programs by drawing directed graphs to represent the program and having the system generate the corresponding program in HOL. The ESL system supports user generation of HOL programs through the manipulation of directed graphs. The components of this graphs (nodes, ports, and connectors) are objects each of which has its own properties and property values. The purpose of the ESL graphical editor is to allow the user to create or edit graph objects which represent programs.
Skills necessary for teaching graphics are addressed. A simple, step by step method of teaching students how to draw different types of graphs is presented. Each step is illustrated by a drawing. Some audience analysis for the determination of appropriateness of the use of different types of graphs is included.
A graphical technique for creating distributed computer programs is investigated and a prototype implementation is described which serves as a testbed for the concepts. The type of programs under examination is restricted to those comprising relatively heavyweight parts that intercommunicate by passing messages of typed objects. Such programs are often presented visually as a directed graph with computer program parts as the nodes and communication channels as the edges. This class of programs, called parts-based programs, is not well supported by existing computer systems; much manual work is required to describe the program to the system, establish the communication paths, accommodate the heterogeneity of data types, and to locate the parts of the program on the various systems involved. The work described solves most of these problems by providing an interface for describing parts-based programs in this class in a way that closely models the way programmers think about them: using sketches of diagraphs. Program parts, the computational modes of the larger program system are categorized in libraries and are accessed with browsers. The process of programming has the programmer draw the program graph interactively. Heterogeneity is automatically accommodated by the insertion of type translators where necessary between the parts. Many decisions are necessary in the creation of a comprehensive tool for interactive creation of programs in this class. Possibilities are explored and the issues behind such decisions are presented. An approach to program composition is described, not a carefully implemented programming environment. However, a prototype implementation is described that can demonstrate the ideas presented.