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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Astronomy sortie missions definition study. Volume 4: Program development requirements

Program development requirements for the selected Astronomy Sortie Missions concept were generated and are presented in four parts as follows: (1)the gross planning requirements that must be considered in subsequent phases of the project; (2)the schedules and logic networks for the design, development, and operation of the overall project; (3)the supporting research and technology required to support the project; and (4)the work breakdown data, from which cost data will be generated. Data reported in each part includes the appropriate rationale with explanations of the guidelines and assumptions that were used in the analyses and estimates.

Source record↗
NASA NTRS1973

Control of a 30 cm diameter mercury bombardment thruster

Control logic functions were established for three automatic modes of operation of a 30-cm thruster using a power conditioner console with flight-like characteristics. The three modes provide: (1) automatic startup to reach thermal stability, (2) steady-state closed-loop control, and (3) the reliable recycling of the high voltages following an arc breakdown to reestablish normal operation. Power supply impedance characteristics necessary for stable operation and the effect of the magnetic baffle on the reliable recycling was studied.

Terdan, F. F.↗
NASA NTRS1973

Effects of nuclear radiation on a high-reliability silicon power diode. 4: Analysis of reverse bias characteristics

The effects of nuclear radiation on the reverse bias electrical characteristics of one hundred silicon power diodes were investigated. On a percentage basis, the changes in reverse currents were large but, due to very low initial values, this electrical characteristic was not the limiting factor in use of these diodes. These changes were interpreted in terms of decreasing minority carrier lifetimes as related to generation-recombination currents. The magnitudes of reverse voltage breakdown were unaffected by irradiation.

Been, J. F.↗
NASA NTRS1973

Debye-Scherrer investigations of experimentally shocked silicates.

Small ballistic ranges were used to perform controlled laboratory shock experiments on 12 selected silicates. Debye-Scherrer investigations of shocked materials revealed a gradual lattice breakdown of crystalline matter under shock. Individual mineral species behave selectively. Sheet silicates break down very easily, followed by tecto-silicates. Chain-, ino- and ortho-silicates are of considerably higher shock resistance. Depending on the mineral species, the first sign of shock damage is evidenced in the long range order at 20-70 kb. At intermediate pressures (100-200 kb) the long range order is essentially destroyed with the short range order heavily disturbed. At pressures exceeding 300 kb tecto-silicates are completely collapsed.

Hoerz, F.↗
NASA NTRS1974

High-voltage distributors

Two distributors reduce high-voltage breakdowns and corona discharges. Both distributors are constructed to prevent air traps and facilitate servicing without soldering. Occurrence of coronas is also minimized due to smooth surfaces of device.

Mcchesney, J. F., Jr.↗
NASA NTRS1972

Interhemispheric comparison of atmospheric circulation features as evaluated from Nimbus satellite data

General circulation parameters in the Northern Hemisphere are calculated using atmospheric thermal structure obtained from Nimbus 3 SIRS multi-channel radiance information. The thermal structure up to 10 mb is obtained by using a regression technique with thickness between pressure levels as the dependent variable. General circulation parameters calculated on a daily basis include zonal and eddy available potential energy, and zonal and eddy kinetic energy. A second set of calculations is performed using National Meteorological Center grid data. A comparison of the two sets of calculations indicates that, although the energies calculated from the SIRS-derived structure underestimate the actual energies, maxima, minima, and trends are well identified. An example of mid-stratospheric energy changes during a breakdown of the polar-night vortex is also given.

Reiter, E. R.↗
NASA NTRS1973

Surface electrical properties experiment, part 1

The design evolution, hardware development, and production history of the surface electrical properties (SEP) experiment are discussed. The SEP transmitter and receiver were designed to be used on the lunar surface during the Apollo 17 mission. The equipment was used to measure lunar surface electrical properties over traverses totalling more than 8 kilometers, for a duration of more than 100 minutes. A comprehensive outline of the techniques, is given along with a simplified detailed breakdown of equipment description and function to outline the principles of operation. A history of the design evolution with trade-off criteria and emphasis on changes caused by decisions reached in solving problems inherent in a fast-paced development program are presented from the viewpoint of overall design concept and in detail for each item of deliverable hardware. There is a brief account of lunar operations.

Kupfer, W. S.↗
NASA NTRS1973

French wind generator systems

The experimental design of a wind driven generator with a rated power of 800 kilovolt amperes and capable of being connected to the main electrical network is reported. The rotor is a three bladed propeller; each blade is twisted but the fixed pitch is adjustable. The asynchronous 800-kilovolt ampere generator is driven by the propeller through a gearbox. A dissipating resistor regulates the machine under no-load conditions. The first propeller on the machine lasted 18 months; replacement of the rigid propeller with a flexible structure resulted in breakdown due to flutter effects.

Noel, J. M.↗
NASA NTRS1973

Unmanned surface traverses of Mars and Moon: Science objectives, payloads, operations

Science objectives and properties to be measured are outlined for long surface traverse missions on Mars and the Moon, with remotely-controlled roving vehicles. A series of candidate rover payloads is proposed for each planet, varying in weight, cost, purpose, and development needed. The smallest weighs 35 kg; the largest almost 300 kg. A high degree of internal control will be needed on the Mars rover, including the ability to carry out complex science sequences. Decision-making by humans in the Mars mission includes supervisory control of rover operations and selection of features and samples of geological and biological interest. For the lunar mission, less control on the rover and more on earth is appropriate. Science portions of the rover mission profile are outlined, with timelines and mileage breakdowns. Operational problem areas for Mars include control, communications, data storage, night operations, and the mission operations system. For the moon, science data storage on the rover would be unnecessary and control much simpler.

Jaffe, L. D.↗
NASA NTRS1974

Performance of coated columbium and tantalum alloys in plasma arc reentry simulation tests

The evaluation of coated refractory metals screened in stagnation model plasma arc tests is reported. Columbium alloys FS-85, C-129Y, and Cb-752 coated with Si-20Cr-20Fe (R512E) were tested at 1390 C. Three silicide coatings on Ta-10W were tested at 1470 C. Half-hour cycles and a 6500 N/sqm stagnation pressure were used. The best R512E coated columbium alloy was FS-85 with first local coating breakdowns occurring in 12 to 50 cycles. At coating defects, low metal recession rates (0.005 mm/min) were generally observed on coated columbium alloys while high rates (0.15 mm/min) were observed on coated Ta-10W. Coated columbium suffered large emittance losses (to below 0.7) due to surface refractory metal pentoxide formation.

Levine, S. R.↗
NASA NTRS1974

Spaceborne synthetic aperture radar pilot study

A pilot study of a spaceborne sidelooking radar is summarized. The results of the system trade studies are given along with the electrical parameters for the proposed subsystems. The mechanical aspects, packaging, thermal control and dynamics of the proposed design are presented. Details of the data processor are given. A system is described that allows the data from a pass over the U. S. to be in hard copy form within two hours. Also included are the proposed schedule, work breakdown structure, and cost estimate.

Source record↗
NASA NTRS1974

Thermomagnetic analysis of meteorites, 2: C2 chondrites

Samples of all eighteen of the known C2 chondrites were analyzed thermomagnetically. For eleven of these, initial Fe3O4 content is low(generally 1%) and the J sub s-T curves are irreversible. The heating curves show variable and erratic behavior, whereas the cooling curves appear to be that of Fe3O4. The saturation moment after cooling is greater (up to 10 times larger) than it is initially. This behavior is interpreted to be the result of the production of magnetite from a thermally unstable phase--apparently FeS. Four of the remaining 7 C2 chondrites contain Fe3O4 as the only significant magnetic phase: initial magnetite contents range from 4 to 13 percent. The remaining three C2 chondrites contain iron or nickel-iron in addition to Fe3O4. These seven C2 chondrites show little evidence of the breakdown of a thermally unstable phase.

Watson, D. E.↗
NASA NTRS1974

Effect of cavitation on fluid stability in polymer thickened fluids and lubricants

The effects of cavitating flow on the polymeric additives used in functional fluids are described. A comparison of thermal and mechanical stability tests for these polymer solutions show distinct differences in the machanism of the polymer degradation. The thermal degradation tests appear to cause an unzippering or depolymerization type of reaction in which there is no particular selectivity based on molecular weight. The mechanical degradation of these fluids appears to be based on molecular weight. Measurements of molecular weight distributions during mechanical degradation show that for a given level of intensity only molecules above a certain minimum size are degraded. The effects of ultrasonic radiation on polymer degradation are reported. Tests were conducted to demonstrate the mechanism of mechanical polymer degradiation in an orifice. A more severe test than the orifice test in which two tapered roller bearings loaded against each other produce the mechanical breakdown is discussed.

Duda, J. L.↗
NASA NTRS1974

Development of a short pulsed solid propellant plasma thruster

The experimental results are summarized that were obtained in the development of a Teflon solid propellant pulsed plasma thruster. The feasibility was established of storing and feeding solid propellant in the form of an open circular loop into an operational thruster. This technique was verified to be practical by feeding over 20 inches of Teflon into a micro-thruster over an accumulated life test of 1858 hours. High energy density capacitors were evaluated under vacuum conditions when the capacitor is coupled directly to a plasma thruster. Numerous early capacitor failures were encountered. It was concluded that essentially all of the failures encountered in a vacuum environment are due to an internal electrical breakdown that will occur inside a capacitor that is not truly hermetically sealed. A steady input power significantly in excess of 130 watts can safely be tolerated if heat conduction can be provided to a sink whose temperature is about 16 C. A vacuum life test of the capacitor bank was carried out while discharging into a milli-lb. (milli-Newton) type pulsed plasma thruster. More than 1500 hours of vacuum testing of this milli-Newton type system has been accumulated without any capacitor problems. Recommendations are made for future capacitor designs.

Guman, W. J.↗
NASA NTRS1974

A comparison of the structure and flow characteristics of the upper troposphere and stratosphere of the Northern and Southern Hemispheres

The general circulations of the Northern and Southern Hemispheres are compared with regard to the upper troposphere and stratosphere using atmospheric structure obtained from satellite, multi-channel radiance data. Specifically, the data are from the Satellite Infrared Spectrometer (SIRS) instrument aboard the Nimbus 3 spacecraft. The inter-hemispheric comparisons are based on two months of data (one summer month and one winter month) in each hemisphere. Topics studied include: mean meridional circulation in the Southern Hemisphere stratosphere; magnitude and distribution of tropospheric eddy heat flux; magnitudes of energy cycle components; and the relation of vortex structure to the breakdown climatology of the Antarctic stratospheric polar vortex.

Adler, R. F.↗
NASA NTRS1974

Interhemispheric comparison of atmospheric circulation features as evaluated from Nimbus satellite data. A comparison of the structure and flow characteristics of the upper troposphere and stratosphere of the Northern and Southern Hemispheres

The general circulations of the Northern and Southern Hemispheres are compared with regard to the upper troposphere and stratosphere, using atmospheric structure obtained from multi-channel radiance data from the satellite infrared spectrometer instrument aboard the Nimbus 3 spacecraft. The inter-hemispheric comparisons are based on two months of data (one summer month and one winter month) in each hemisphere. Topics studied include: (1) mean meridional circulation in the Southern Hemisphere stratosphere; (2) magnitude and distribution of tropospheric eddy heat flux; (3) relative importance of standing and transient eddies in the two hemispheres; (4) magnitudes of energy cycle components; and (5) the relation of vortex structure to the breakdown climatology of the Antarctic stratospheric polar vortex.

Reiter, E. R.↗
NASA NTRS1974

Life sciences payload definition and integration study. Volume 2: Requirements, design, and planning studies for the carry-on laboratories

The task phase concerned with the requirements, design, and planning studies for the carry-on laboratory (COL) began with a definition of biomedical research areas and candidate research equipment, and then went on to develop conceptual layouts for COL which were each evaluated in order to arrive at a final conceptual design. Each step in this design/evaluation process concerned itself with man/systems integration research and hardware, and life support and protective systems research and equipment selection. COL integration studies were also conducted and include attention to electrical power and data management requirements, operational considerations, and shuttle/Spacelab interface specifications. A COL program schedule was compiled, and a cost analysis was finalized which takes into account work breakdown, annual funding, and cost reduction guidelines.

Source record↗
NASA NTRS1974

Skylab S-191 spectrometer single spectral scan analysis program

Documentation and user information for the S-191 single spectral scan analysis program are reported. A breakdown of the computational algorithms is supplied, followed by the program listing and examples of sample output. A copy of the flow chart which describes the driver routine in the body of the main program segment is included.

Downes, E. L.↗