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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 1,351 records · Page 75
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Method for fabricating a mass spectrometer inlet leak

A method of fabricating an inlet leak for measuring chemically reactive gases is proposed. The method involves the steps of preparing a selected internal surface of a high melting point metal tubing for sealing to a glass tubing. A portion of the glass tubing is inserted into the prepared portion of the metal tubing, the glass tubing having an outer diameter substantially the same as the inner diameter of the metal tubing. The inserted glass tubing is sealed to the internal surface of the metal tubing; the glass tubing is drawn under a magnifying device to reduce the entire interior diameter thereof to substantially two microns; and an end portion of the drawing glass tubing is broken away.

Harris, R. F.↗
NASA NTRS1976

Wheat signature modeling and analysis for improved training statistics

The author has identified the following significant results. The spectral, spatial, and temporal characteristics of wheat and other signatures in LANDSAT multispectral scanner data were examined through empirical analysis and simulation. Irrigation patterns varied widely within Kansas; 88 percent of wheat acreage in Finney was irrigated and 24 percent in Morton, as opposed to less than 3 percent for western 2/3's of the State. The irrigation practice was definitely correlated with the observed spectral response; wheat variety differences produced observable spectral differences due to leaf coloration and different dates of maturation. Between-field differences were generally greater than within-field differences, and boundary pixels produced spectral features distinct from those within field centers. Multiclass boundary pixels contributed much of the observed bias in proportion estimates. The variability between signatures obtained by different draws of training data decreased as the sample size became larger; also, the resulting signatures became more robust and the particular decision threshold value became less important.

Nalepka, R. F.↗
NASA NTRS1977

Method for obtaining aerodynamic data on hypersonic configurations with scramjet exhaust flow simulation

A hypersonic wind tunnel test method for obtaining credible aerodynamic data on a complete hypersonic vehicle (generic X-24c) with scramjet exhaust flow simulation is described. The general problems of simulating the scramjet exhaust as well as accounting for scramjet inlet flow and vehicle forces are analyzed, and candidate test methods are described and compared. The method selected as most useful makes use of a thrust-minus-drag flow-through balance with a completely metric model. Inlet flow is diverted by a fairing. The incremental effect of the fairing is determined in the testing of two reference models. The net thrust of the scramjet module is an input to be determined in large-scale module tests with scramjet combustion. Force accounting is described, and examples of force component levels are predicted. Compatibility of the test method with candidate wind tunnel facilities is described, and a preliminary model mechanical arrangement drawing is presented. The balance design and performance requirements are described in a detailed specification. Calibration procedures, model instrumentation, and a test plan for the model are outlined.

Hartill, W. R.↗
NASA NTRS1976

Atmospheric, Magnetospheric and Plasmas in Space (AMPS) spacelab payload definition study; volume 4: Part 2, Labcraft payload general specification

The Labcraft Payload General Specification (LPGS) amplifies those general requirements in the Labcraft Program Specification (LPS) to ensure that all hardware, software, and STS elements will successfully function as an integrated system to accomplish the objectives of the first Labcraft mission. Contract End Item Specifications (CEIS) and Procurement Drawings (PDs) prepared and implemented for all deliverable hardware and software elements are discussed.

Keeley, J. T.↗
NASA NTRS1976

Guidelines for advanced manned space vehicle program, June 1960

A very broad mission objective was established; i.e., manned circumlunar flight and return to earth. It is implicit that the Saturn will be the primary propulsion system for this mission. The following attempts to: (1) define the objective so as to achieve as much capability in the vehicle as possible; (2) draw on Mercury experience to provide broad guidelines for vehicle performance and safety; (3) provide flexibility in the vehicle capability in the event that the manned lunar mission is proved to be subject to unacceptable risk in the target time period; and (4) indicate problem areas where work appears to be particularly needed.

Gilruth, R. R.↗
NASA NTRS1977

Application of LANDSAT data to delimitation of avalanche hazards in Montane Colorado

The author has identified the following significant results. Many avalanche hazard zones can be identified on LANDSAT imagery, but not consistently over a large region. Therefore, regional avalanche hazard mapping, using LANDSAT imagery, must draw on additional sources of information. A method was devised that depicts three levels of avalanche hazards according to three corresponding levels of certainty that active avalanches occur. The lowest level, potential avalanche hazards, was defined by delineating slopes steep enough to support avalanches at elevations where snowfall was likely to be sufficient to produce a thick snowpack. The intermediate level of avalanche hazard was interpreted as avalanche hazard zones. These zones have direct and indirect indicators of active avalanche activity and were interpreted from LANDSAT imagery. The highest level of known or active avalanche hazards was compiled from existing maps. Some landslides in Colorado were identified and, to a degree, delimited on LANDSAT imagery, but the conditions of their identification were highly variable. Because of local topographic, geologic, structural, and vegetational variations, there was no unique landslide spectral appearance.

Knepper, D. H., Jr.↗
NASA NTRS1976

Solar rotation during the Maunder Minimum

Solar surface rotation has been measured from sunspot drawings made in A.D. 1642-1644, probable differences from present-day rates are found. The 17th-century sunspots rotated faster near the equator by 3 or 4%, and the differential rotation between zero and + or - 20 deg latitude was enhanced by about a factor 3. These differences are consistent features in both spots and groups of spots and in both hemispheres. It is assumed that this apparent change in surface rotation was related to the ensuing dearth of solar activity (the Maunder Minimum) which persisted until about 1715.

Eddy, J. A.↗
NASA NTRS1976

The Viking seismic experiment

A three-axis short-period seismometer is now operating on Mars in the Utopia Planitia region. The noise background correlates well with wind gusts. Although no quakes have been detected in the first 60 days of observation, it is premature to draw any conclusions about the seismicity of Mars. The instrument is expected to return data for at least 2 years.

Anderson, D. L.↗
NASA NTRS1976

Space solar power - An available energy source

The development of satellite solar power stations is described with attention given to station design and assembly in space. Problems associated with conversion of solar energy into microwaves and with getting the station into orbit are considered. The use of a solar propulsion system for pushing the station to high orbit is discussed along with questions of station lifetime (estimated to be about thirty years). The paper is copiously illustrated with drawings projecting various aspects of station design and utilization.

Ferdman, S.↗
NASA NTRS1976

Emission object in Orion

The note draws attention to a structural feature in the Orion nebula, consisting of a parachute-shaped object converging on 64 Orionis, noted on H alpha photographs of the Orion nebula taken with the 76-cm Allegheny refractor. The same feature shows up clearly on a photograph taken in 1909 with the Mount Wilson 152-cm reflector, and on a photograph taken with the Palomar 5-m reflector. Measurements made on these three plates indicate a possible expansion of the object of about 3.6 seconds of arc per century, corresponding to a tangential velocity of about 90 to 100 km/sec. If the expansion continued at a linear rate, an explosive event may have occurred approximately 900 years ago.

Feibelman, W. A.↗
NASA NTRS1976

Physical properties of thin-film field emission cathodes with molybdenum cones

Field emission cathodes fabricated using thin-film techniques and electron beam microlithography are described, together with effects obtained by varying the fabrication parameters. The emission originates from the tip of molybdenum cones that are about 1.5 micron tall with a tip radius around 500 A. Such cathodes have been produced in closely packed arrays containing 100 and 5000 cones as well as singly. Maximum currents in the range 50-150 microamp per cone can be drawn. Life tests with the 100-cone arrays drawing 2 mA total emission (or 3 A per sq cm) have proceeded in excess of 7000 hr with about a 10% drop in emission current. Studies are presented of the emission characteristics and current fluctuation phenomena. It is tentatively concluded that the emission arises from only one or a few atomic sites on the cone tips.

Spindt, C. A.↗
NASA NTRS1976

Development of a preliminary design of a method to measure the effectiveness of virus exclusion during water process reclamation at zero-G

Organon Diagnostics has developed, under NASA sponsorship, a monitoring system to test the capability of a water recovery system to reject the passage of viruses into the recovered water. In this system, a non-pathogenic marker virus, bacteriophage F2, is fed into the process stream before the recovery unit and the reclaimed water is assayed for its presence. An engineering preliminary design has been performed as a parallel effort to the laboratory development of the marker virus test system. Engineering schematics and drawings present a preliminary instrument design of a fully functional laboratory prototype capable of zero-G operation.

Fraser, A. S.↗
NASA NTRS1977

The structure of cometary ionospheres. II - CO-rich comets

The structure of the ionosphere of a CO-rich comet is computed using two different models. The first one, the photochemical model, assumes that the dissociation and ionization of cometary neutrals and ions are due to photoionization, and photodissociation by solar UV radiation together with dissociative recombinations and ion-neutral reactions. The second one, the internal source model, also incorporates the ionization and dissociation effects of an electric current discharging through the inner coma. The generation of this current has been discussed in earlier papers. It is concluded that the internal source model can explain qualitatively the basic morphology of the ionospheres of CO-rich comets such as Humason (1962, VIII) and Morehouse (1908, III), whereas the photochemical model cannot. The main aim of this paper is not so much to provide accurate numerical estimates as to draw attention to a process which may very well dominate the structures of cometary ionospheres.

Ip, W.-H.↗
NASA NTRS1976

Multiplexor and sensor system tradeoff study

The influence of certain sensor parameters on the accuracy of information extracted from satellite image data is studied, using a digital processing flow to simulate the effects of the sensor parameters. The method employed was to select representative images; scan and digitize them; process the digital data to simulate the effects of presampling filters, instantaneous field of view (IFOV) size and shape, sampling rates, noise, and word length; record the processed data on film; evaluate the film images; and draw conclusions from the evaluations. The study showed that presampling filters are not required to suppress aliasing, that the choice of square and circular IFOV shapes is not important, and that increased horizontal and vertical sampling rates produce an increase in apparent resolution. Work with low-contrast targets revealed a definite maximum in the tradeoff between IFOV size and SNR.

Ferneyhough, D. G., Jr.↗
NASA NTRS1977

Characteristics of an anechoic chamber for fan noise testing

Acoustical and mechanical design features of NASA Lewis Research Center's engine fan noise facility are described. Acoustic evaluation of the 1420-m (50,000-ft) chamber, which is lined with an array of stepped wedges, is described. Results from the evaluation in terms of cut-off frequency and non-anechoic areas near the walls are detailed. Fan models with 0.51-m (20-in) diameters are electrically driven to 20,600 rpm in either the inlet mode (drawing air from the chamber) or exhaust mode (discharging air into the chamber) to facilitate study of both fore and aft fan noise. Inlet noise characteristics of the first fan tested, the JT8D Refan, are discussed and compared to full-scale levels. Turbulence properties of the inlet flow and acoustic results are compared with and without a turbulence reducing screen over the fan inlet.

Wazyniak, J. A.↗
NASA NTRS1977

Remote sensing of estuarine fronts and their effects on pollutants

Estuarine fronts represent regions of extremely high gradient or discontinuity in various parameters of physical interest, the most important being the water velocity and density fields. Such fronts strongly influence pollutant dispersion by capturing oil slicks and other pollutants concentrated in surface films and drawing them down into the water column. Aircraft and boats were combined to study the behavior of different types of fronts in Delaware Bay and their effect on pollutants in order to provide a basis for improving an oil drift and spreading model. Imagery from the Landsat satellites provided the most effective means of determining the location and extent of frontal systems over all portions of the tidal cycle. This information is being used to modify the oil drift and spreading model.

Klemas, V.↗
NASA NTRS1976

A solar origin for the large lunar magnetic field at 4.0 billion yr ago

A new method (Shaw, 1974) for paleointensity determination has been applied to three subsamples of one polymict breccia, 72215 (of age 4.0 billion yr) to yield an average paleointensity of 0.41 Oe at the Taurus-Littrow region of the moon around the time of breccia formation. Of the present models for lunar magnetism, only the Sonett and Runcorn (1974) model of a central iron core dynamo can explain the presence of such a large field in early lunar history. However, because of the similarity in size of this field and that for the early solar system deduced from carbonaceous chondrites, we draw attention to an apparently little-considered possibility: that the large magnetic field in early lunar history was external and solar in origin, and emanated from a pre-main sequence T-Tauri stage sun. Therefore, there should be no record of such a large magnetic field in lunar rocks younger than approximately 4.0 billion yr.

Banerjee, S. K.↗