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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 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Dual shear plate power processor packaging design

The use of solar electric propulsion (SEP) for spacecraft primary propulsion imposes an extreme range of operational and environmental design requirements associated with the diversity of missions for which solar electric primary propulsion is advantageous. One SEP element which is particularly sensitive to these environmental extremes is the power processor unit (PPU) which powers and controls the electric ion thruster. An improved power processor thermal-mechanical packaging approach, referred to as dual shear plate packaging, has been designed to accommodate these different requirements with minimum change to the power processor design. Details of this packaging design are presented together with test results obtained from thermal-vacuum and structural-vibration tests conducted with prototype hardware.

Franzon, A. O.↗
NASA NTRS1974

Study of the organic matter in the DSDP /JOIDES/ cores, legs 10-15

The composition of the organic matter collected on legs 10 to 15 of the DSDP (Deep Sea Drilling Project) is described. Distributions of various alkanes, carboxylic acids, steroids and terpenoids, isoprenoid ketones and olefins, and aromatic polycyclic compounds are given. Samples analyzed had terrigenous clay components, with variable organic carbon contents and thus diverse solvent soluble matter. The distribution patterns for the various compound series monitored were of marine derivation, with the terrigenous components superimposed. Diagenesis of steroids appeared to proceed via both stanones and stanols to their respective steranes. Degradative processes were observed to be operative: oxidative products, mainly ketones derived from steroids and phytol, were identified, probably due to microbial alteration prior to or during sedimentation. Loss of alkane and fatty acid C preferences and presence of polycyclic aromatics evinced maturation. Results indicate that the accumulation, degradation, diagenesis and maturation of organic matter occurs in various steps in the deep sea environment.

Simoneit, B. R. T.↗
NASA NTRS1974

Petrography and classification of Apollo 17 non-mare rocks with emphasis on samples from the Station 6 boulder

The Apollo-17 nonmare rock collection consists largely of polymict breccias lithified by impact and characterized by a variety of types of lithic clasts, concentrations of siderophile elements that indicate substantial meteoritic contamination, and contents of metallic iron well above those of mare basalts. These materials may be subdivided into two compositional groups, one with 70-80% feldspar and the other with 50-60% feldspar. The high-feldspar group includes two characteristic textures: coarsely poikilitic and granulitic. The low-feldspar group includes (1) fragmental breccias with the most diverse lithic clast populations of all breccias and (2) crystalline breccias with poikilitic and subophitic to micropoikilitic textures containing tabular feldspar, granular textures with anhedral feldspar, and clast-rich ophitic textures containing less euhedral feldspar. In the poikilitic and subophitic to micropoikilitic textures, the clast population is dominated by the high-feldspar lithologies and An(94-47) plagioclase grains, indicating that these more refractory lithologies were abundant in the material from which the less feldspathic crystalline rocks formed.

Simonds, C. H.↗
NASA NTRS1974

Labile and nonlabile element relationships among Apollo 17 samples

Volatile and nonvolatile trace element contents in a suite of Apollo 17 soils and rocks are studied. It is found that the halogens exhibit a remarkable degree of coherence because of their apparent diverse geochemistry, that the F-Cl-P2O5 coherence previously noted persists among Apollo 17 samples, that both U and Ru-Os support lateral mixing of regolith on a local scale, and that the meteoritic Ru/Os ratios found in a few samples are attributed to primitive lunar material that has not been extensively recycled.

Jovanovic, S.↗
NASA NTRS1975

Mars

The evolution and physical structure of Mars are discussed primarily on the basis of Mariner 9 observations. The Martian atmosphere, density, and iron abundance are compared with those of earth, and it is noted that the planet was probably formed in less than 100,000 years. Stages in Martian differentiation are described together with the atmospheric composition, condensation and dust clouds, and surface winds. The surface is shown to have a wide diversity of geological landforms resulting from a variety of processes, including meteoroid bombardment, volcanic and tectonic activity, sapping, the action of running water, and wind action. Described landforms include impact craters, volcanic plains and domes, shield volcanoes, sinuous channels and gullies apparently formed by running water, and the enormous canyon system. Mechanisms for climatic change are considered, and questions are posed regarding the possibility of life on Mars.

Pollack, J. B.↗
NASA NTRS1975

Mars - A planet with a complex surface evolution

The surface of Mars has evolved to its present form through a complex sequence of tectonism and associated volcanism, impact processes, water erosion, mass movements, and wind action. The diversity of geological processes active in past Martian history far exceeded most predictions. By the same token, predictions of processes modifying the satellites of the outer planets may fall far short of the true range of phenomena. A summary of present though with regard to Martian surface evolution is presented to serve as a case in point of the value of imagery and topography data in making interpretations of geological histories.

Arvidson, R. E.↗
NASA NTRS1975

Connective stability of competitive equilibrium

The purpose of this paper is to derive necessary and sufficient conditions for the connective stability of nonlinear matrix systems described by the equation x-dot = A(t, x) x, where the matrix A(t, x) has time-varying nonlinear elements. The results obtained can be used to study the stability of competitive equilibrium in fields as diverse as economics and engineering, model ecosystems, and the arms race.-

Siljak, D. D.↗
NASA NTRS1975

Transportation and general aviation in Virginia

The diversity of Virginia is examined with respect to its transportation facilities and services, the Virginia Air Transportation System Plan, regionalism, and selected case studies of individual facilities.

Source record↗
NASA NTRS1975

Design, development and manufacture of a breadboard radio frequency mass gauging system

The feasibility of the RF gauging mode, counting technique was demonstrated for gauging liquid hydrogen and liquid oxygen under all attitude conditions. With LH2, it was also demonstrated under dynamic fluid conditions, in which the fluid assumes ever changing positions within the tank, that the RF gauging technique on the average provides a very good indication of mass. It is significant that the distribution of the mode count data at each fill level during dynamic LH2 and LOX orientation testing does approach a statistical normal distribution. Multiple space-diversity probes provide better coupling to the resonant modes than utilization of a single probe element. The variable sweep rate generator technique provides a more uniform mode versus time distribution for processing.

Source record↗
NASA NTRS1975

Integrated mass transportation system study/definition/implementation program definition

Specific actions needed to plan and effect transportation system improvements are identified within the constraints of limited financial, energy and land use resources, and diverse community requirements. A specific program is described which would develop the necessary generalized methodology for devising improved transportation systems and evaluate them against specific criteria for intermodal and intramodal optimization. A consistent, generalized method is provided for study and evaluation of transportation system improvements.

Ransone, R. K.↗
NASA NTRS1976

Survey of future requirements for large space structures

The future requirements for large space structures were examined and the foundation for long range planning of technology development for such structures is provided. Attention is concentrated on a period after 1985 for actual use. Basic ground rule of the study was that applications be of significant importance and have promise of direct economic benefit to mankind. The inputs to the study came from visits to a large number of government and industrial organizations, written studies in current literature, and approximate analyses of potential applications. The paper identifies diverse space applications for large area structures in three general categories: (1) large surfaces for power, (2) large antenna to receive and transmit energy over the radio frequency bandwidth, and (3) space platforms to provide area for general utilizations.

Hedgepeth, J. M.↗
NASA NTRS1975

Assessment of practicality of remote sensing techniques for a study of the effects of strip mining in Alabama

Because of the volume of coal produced by strip mining, the proximity of mining operations, and the diversity of mining methods (e.g. contour stripping, area stripping, multiple seam stripping, and augering, as well as underground mining), the Warrior Coal Basin seemed best suited for initial studies on the physical impact of strip mining in Alabama. Two test sites, (Cordova and Searles) representative of the various strip mining techniques and environmental problems, were chosen for intensive studies of the correlation between remote sensing and ground truth data. Efforts were eventually concentrated in the Searles Area, since it is more accessible and offers a better opportunity for study of erosional and depositional processes than the Cordova Area.

Hughes, T. H.↗
NASA NTRS1975

Generating social impact scenarios: A key step in making technology assessment studies

The MITRE methodological studies were conducted to define relevant questions in relation to the concept of total impact analysis and to provide a procedure for integrating diverse checklists of questions which trace the initial and secondary impacts of any major technological application or of society's attempts to respond to or redirect that application. Some of the results of that study are presented in tabular form.

Jones, M. V.↗
NASA NTRS1975

Experiment Pointing Subsystems (EPS) requirements for Spacelab missions

The goal of the experiment pointing subsystems (EPS) is to accommodate a broad spectrum of instrument types by providing a number of stability and control functions that greatly exceed the capability of the shuttle. These functions include target acquisition, target tracking through wide gimbal ranges, stabilization, simultaneous pointing to one or more targets, instrument rastering, and on-orbit calibration. The experiments will vary widely in size, weight, geometry, and instrument types, and many have not been completely defined. This great diversity of requirements reflects the long term plans of the user community and establishes challenging performance requirements for the EPS.

Nein, M. E.↗
NASA NTRS1976

Analysis of recreational land using Skylab data

The author has identified the following significant results. S192 data collected on 5 August 1973 were processed by computer to produce a classification map of a part of the Gratiot-Saginaw State Game Area in south central Michigan. A 10-category map was prepared of an area consisting of diverse terrain types, including forests, wetlands, brush, and herbaceous vegetation. An accuracy check indicated that 54% of the pixels were correctly recognized. When these ten scene classes were consolidated to a 5-category map, the accuracy increased to 72%. S190 A, S190 B, and S192 data can be used for regional surveys of existing and potential recreation sites, for delineation of open space, and for preliminary evaluation of geographically extensive sites.

Sattinger, I. J.↗
NASA NTRS1975

Layered classification techniques for remote sensing applications

The single-stage method of pattern classification utilizes all available features in a single test which assigns the unknown to a category according to a specific decision strategy (such as the maximum likelihood strategy). The layered classifier classifies the unknown through a sequence of tests, each of which may be dependent on the outcome of previous tests. Although the layered classifier was originally investigated as a means of improving classification accuracy and efficiency, it was found that in the context of remote sensing data analysis, other advantages also accrue due to many of the special characteristics of both the data and the applications pursued. The layered classifier method and several of the diverse applications of this approach are discussed.

Swain, P. H.↗
NASA NTRS1975

Land use and environmental assessment in the central Atlantic region

Data from high altitude aircraft, LANDSAT and Skylab were used in a comprehensive regional survey of land use and its associated environmental impact in the Central Atlantic Regional Ecological Test Site (CARETS). Each sensor system has advantages that were demonstrated by producing experimental land use maps and other data products, applying them to typical problems encountered in regional planning and environmental impact assessment, and presenting the results to prospective users for evaluation. An archival collection of imagery, maps, data summaries, and technical reports was assembled, constituting an environmental profile of the central Atlantic region. The investigation was organized into four closely-related modules, a land use information module, an environmental impact module, a user interaction and evaluation module, and a geographic information systems module. Results revealed a heterogeneous user community with diverse information needs, tending, however, definitely toward the higher-resolution sensor data and the larger-scale land use maps and related information products. Among project recommendations are greater efforts toward improving compatibility of federal, state, and local land use information programs, and greater efforts toward a broader exchange of imagery, computer tapes, and land use information derived therefrom.

Alexander, R. H.↗