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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 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Experiment S029: Earth-Moon libration regions photography

Eleven photographs were taken of the L sub 4 earth-moon libration region during the Gemini 12 mission. The objective was to investigate the possible existence of clouds or particles of dust orbiting the earth in the L sub 4 region by the use of photographic techniques. No identifiable data were found in the first sequence of five photographs. Star field images could be recognized in two photographs of the second sequence of pictures. A light flare, of unknown source but possibly caused by light refraction from the window of the spacecraft, was recorded in both pictures. A reconstructed star field region (as photographed) is shown Isodensitraces of the two recognizable star fields were made; however, no conclusive results were obtained.

Morris, E. C.↗
NASA NTRS1971

Structure and evolution of fossil H II regions

The structure and evolution of a fossil H II region created by a burst of ionizing radiation from a supernova is considered. The cooling time scale for the shell is about 10 to the 6th power years. Superposition of million-year-old fossil H II regions may account for the temperature and ionization of the interstellar medium. Fossil H II regions are unstable to growth of thermal condensations. Highly ionized filamentary structures form and dissipate in about 10,000 years. Partially ionized clouds form and dissipate in about 10 to the 6th power years.

Mccray, R.↗
NASA NTRS1972

Long duration solar active regions

Nimbus 3 and 4 observations of ultraviolet active regions of the sun have been investigated. It is not clear what is producing these UV-active regions, however, it could be changes in the overall intensity of the solar continuum near the region of the temperature minimum, or the solar flux variations that have been seen could be due to a continuous type of absorption like that associated with the ionization limits of elements such as aluminum, silicon, or magnesium.

Heath, D.↗
NASA NTRS1972

High altitude color photography as a tool for regional analysis: As demonstrated for southeastern Florida

High altitude color and color infrared photography of the tri-county region of southeast Florida made it feasible to evaluate its potential for quantifying the dimensions of regional change. Attention was focused upon three main aspects of change in the region, which in fact overlap. These were; (1) the transformation of the southeast Florida wetlands; (2) the expansion of agriculture; and (3) the growth of the urbanized area. The development analyzed covered the period of thirteen years from 1956 to 1969. Results using this new 18 km photography were superior because of the degree of resolution, the combined power of color and color infrared interpretation, and the large area covered by each frame. The greatest advantage of high altitude imagery is the time-saving element, since it is possible to delineate and identify major geographic patterns over thousands of sq km very rapidly.

Eyre, L. A.↗
NASA NTRS1972

Measurements of O(1 D) quenching rates in the F-region

In-situ determinations of the quenching of O(1 D) atoms by N2 and O2 molecules were made from observations of 6300 A nightglow intensity enhancements produced by the Platteville 1.6 MW transmitter. The heating of F-region electrons near the point of reflection of the RF wave leads to electron impact excitation of oxygen atoms to the O(1 D) state. It is shown that the resulting region of enhance 6300 A emission is localized to the region of electron energy absorption for heating at the lower altitudes. At 225 km the measured time constants for intensity buildup following transmitter turn-on and for intensity decay following turn-off are identical and equal to (13 plus or minus 1) sec. Time constants varying from 30 to 80 sec are found for the altitude range 260 to 300 km. The inferred quenching coefficient for the whole altitude range, 225 to 300 km, is 4.4 + 2 or - 1 x 10 to the minus 11th power cu cm/sec at 950 K, in good agreement with laboratory data. The quenching frequency obtained at 225 km, when referred to the altitude 120 km, is equal to (21 plus or minus 2)/sec, in agreement with less direct ionospheric determinations.

Sipler, D. P.↗
NASA NTRS1971

Application of the chromospheric magnetograph to active regions.

It is shown how to determine the magnetic field structure in active regions from the H-alpha morphology. The role of EFR (emerging flux region) as a bipolar region of velocity downflow is also shown. It is pointed out that, since all new magnetic flux emerges in strictly bipolar form, complex spot groups must result from surface interaction, hence most of the solar surface field may be produced on the surface.

Zirin, H.↗
NASA NTRS1971

Coronagraphic observations of an enhanced coronal region. I - Fe XIII and Ni XV emission line data.

Observation of nine coronal emission lines representing five stages of Fe ionization and one stage of Ni in an enhanced coronal region. The data from these observations are presented along with a density model of the enhanced region obtained from the Fe XIII and Ni XV emission line ratios as a function of position angle. The electron densities obtained from Fe XIII lines range from 10 to the 8th to 10 to the 9th per cu cm, and are slightly lower for Ni XV line data. Estimates of the variation of temperature over the enhanced region are inferred from the observed line intensities.

Fisher, R.↗
NASA NTRS1972

Partially ionized gas flow and heat transfer in the separation, reattachment, and redevelopment regions downstream of an abrupt circular channel expansion.

Heat transfer and pressure measurements obtained in the separation, reattachment, and redevelopment regions along a tube and nozzle located downstream of an abrupt channel expansion are presented for a very high enthalpy flow of argon. The ionization energy fraction extended up to 0.6 at the tube inlet just downstream of the arc heater. Reattachment resulted from the growth of an instability in the vortex sheet-like shear layer between the central jet that discharged into the tube and the reverse flow along the wall at the lower Reynolds numbers, as indicated by water flow visualization studies which were found to dynamically model the high-temperature gas flow. A reasonably good prediction of the heat transfer in the reattachment region where the highest heat transfer occurred and in the redevelopment region downstream can be made by using existing laminar boundary layer theory for a partially ionized gas. In the experiments as much as 90 per cent of the inlet energy was lost by heat transfer to the tube and the nozzle wall.

Back, L. H.↗
NASA NTRS1972

Low energy electron precipitation and the ionospheric F-region in and north of the auroral zone.

Use of low-elevation sounding rocket (Polar 1) in the exploration of the F region morphology in and north of the auroral zone over northern Norway. The rocket which moved over a horizontal distance of some 400 km inside the F region, monitored low-energy electron precipitation and various upper-atmosphere excitation and ionization processes. The latitudinal variations of the less than 1 keV energy electron fluxes showed excellent agreement with corresponding variations in the F-region electron density and the O I (6300 A) emission below the rocket, indicating that the low-energy electrons are the main sources for these phenomena at these high latitudes. An N2(+) (4278 A) arc was located near the decrease in the 40-keV electron fluxes. This arc was produced by a nearly monoenergetic influx of some 3-keV electrons. The expected luminosity profile derived from this energy spectrum differs significantly from the observed one, and possible explanations for the discrepancy are discussed.

Evans, D. S.↗
NASA NTRS1972

A method for integrating the boundary-layer equations through a region of reverse flow.

Development of a procedure for numerically integrating the boundary-layer equations through a region of reverse flow which takes downstream influence into account. This method is applied to the problem of uniform flow past a parallel flat plate of finite length whose surface has a constant velocity directed opposite to that of the main stream. Although singularities occur at both the point of detachment (x sub s) and reattachment (x sub r) of the psi = 0 streamline, this integration technique provides a solution which ceases to apply only in the close proximity of these singular points. From this solution it is evident that, throughout a large portion of the separated region, the flow is strongly affected by conditions near x sub r, thereby demonstrating the importance of allowing information to be transmitted upstream in a region of backflow. Near x sub s, however, it is found that, in spite of the presence of reverse flow, the solution has a self-similar form in this particular example.

Klemp, J. B.↗
NASA NTRS1972

X-ray study of solar plage regions and a small flare.

The O VII and Ne IX resonance line and 5 keV continuum emission of a small solar flare are interpreted on the basis of a model in which the emission measure of the region is an exponentially decreasing function of temperature. Good agreement with all three sets of data is obtained - a result not possible on the basis of an isothermal approximation. The change in the emission of the flare over a two minute interval appears to be consistent with a simple cooling of the region. Computation of the contribution function versus temperature for each emission indicates that each predominantly comes from a physically separate volume within the feature. The emission measure distribution for the flare is distinctly flatter than that of five plage regions which tend to have similar slopes and which are in turn flatter than the general corona.

Acton, L. W.↗
NASA NTRS1972

Photoelectron escape fluxes over the equatorial and midlatitude regions

Satellite measurements of photoelectron escape flux around noontime made by Explorer 31 in 600-800 km altitude range are reported for the equatorial and midlatitude regions. The pitch angle distributions and the spectral distributions are derived from the data. Analyzed data show that the flux for equatorial regions is lower by a factor 2 to 3 in comparison to that of midlatitude regions. Theoretical calculations are also made to compare with observed escape fluxes.

Narasingarao, B. C.↗
NASA NTRS1973

Utilizing ERTS-A imagery for tectonic analysis through study of the Bighorn Mountains Region

The author has identified the following significant results. Preliminary vegetation analysis has been undertaken on MSS scene 1085-17294, Oct. 16, 1973 in the Bighorn region. Forest Service maps showing detailed distribution of dominant forest types have been compared with MSS bands 5 and 7 positive transparencies, enlarged positive prints, and color imagery produced on an Addcol viewer. Patterns on the ERTS imagery match those on the Forest Service maps quite well. A tectonic map ovearlay of MSS band 7 of the Bighorn region reveals a strong concentration of linears in the uplift as compared to basins. Folds in the Bighorn Basin are visible where not covered by post-Paleocene deposits. In regions where far less is known of the geology than in this area, it might be possible to predict the subsurface occurrence of folds and lineaments on the basis of imagery analysis and more confidently explore covered areas for concealed oil structures and mineral deposits.

Hoppin, R. A.↗
NASA NTRS1973

Regional Tectonic Control of Tertiary Mineralization and Recent Faulting in the Southern Basin-Range Province, an Application of ERTS-1 Data

Research based on ERTS-1 MSS imagery and field work in the southern Basin-Range Province of California, Nevada and Arizona has shown regional tectonic control of volcanism, plutonism, mineralization and faulting. This paper covers an area centered on the Colorado River between 34 15' N and 36 45' N. During the mid-Tertiary, the area was the site of plutonism and genetically related volcanism fed by fissure systems now exposed as dike swarms. Dikes, elongate plutons, and coeval normal faults trend generally northward and are believed to have resulted from east-west crustal extension. In the extensional province, gold silver mineralization is closely related to Tertiary igneous activity. Similarities in ore, structural setting, and rock types define a metallogenic district of high potential for exploration. The ERTS imagery also provides a basis for regional inventory of small faults which cut alluvium. This capability for efficient regional surveys of Recent faulting should be considered in land use planning, geologic hazards study, civil engineering and hydrology.

Bechtold, I. C.↗
NASA NTRS1973

Nature and origin of layered deposits of the Martian polar regions

Layered deposits in the Martian polar regions are interpreted as accumulations of dust derived from atmospheric suspensions. Depressed and eroded terrains of the equatorial region are considered to be the principal sources of dust. A depositional model based on polar precipitation of dust predicts the formation of a vast, dome-shaped, featureless plateau underlain by layered deposits and occupying most of the area of annual frost cover. The rates of accumulation of dust and water ice in the polar regions have been estimated on the basis of atmospheric conditions in the present era. The analysis indicates an accumulation time of about 500 x 1 million years for the layered deposits and the presence of significant quantities of water ice in the deposits beneath the perennial cap.

Cutts, J. A.↗
NASA NTRS1973

Gamma-ray emission from the region of the Galactic center.

A combination nuclear-emulsion-spark-chamber gamma-ray telescope has been used to study the region of sky that includes the Galactic center. Ninety-five per cent confidence upper limits on the flux from the reported sources G-gamma 2+3 and Sgr gamma-1 were placed at .000044 and .000088 photons per sq cm per sec, and a similar limit on the emission from the Galactic center as a point source was placed at .000033 photons per sq cm per sec. No enhanced emission was observed from the Galactic plane. Three regions of enhanced emission were observed that had a combined Poisson probability of occurrence of less than .005. One of these is associated with a region of enhanced emission reported by other workers.

Dahlbacka, G. H.↗
NASA NTRS1973

Flares associated with EFR's /emerging flux regions/.

Examination of a moderately active sunspot group, McMath 9735, showed that 15 of 16 flares observed on Oct. 20-21, 1968, occurred near, and were preceded by, at least one of several EFR's (emerging flux regions) in the area. Flares were larger and more numerous when: (1) the EFR appeared close to already existing spots, (2) a large amount of filament reorientation was occurring, and when (3) the EFR was most active - i.e., it was increasing in area and brightness and was accompanied by violent surging and great brightness fluctuations at the feet of the dark fibrils. Only two flares occurred at an 'inverted' EFR - i.e., a leading spot with f polarity; however the largest event (2B) of the 15 quickly spread to this region after starting in a different EFR. A sunspot appeared in the inverted emerging flux region less than three hours after the flares. However, this is thought to be merely an indication of the growing EFR and therefore a secondary effect.

Vorpahl, J. A.↗
NASA NTRS1973

Application of Nimbus 4 THIR 6.7-micron observations to regional and global moisture and wind field analyses.

The Nimbus 4 temperature-humidity infrared radiometer (THIR) monitors radiation in the 6.5 to 7.2-micron water vapor absorption region with a 23-km spatial resolution at the subsatellite point. Radiation monitored in this spectral region results primarily from emission in the 250 to 500-mb region of the upper troposphere. The THIR 6.7-micron observations are readily available in photofacsimile imagery form which shows very distinctive patterns associated with spatial variations in atmospheric water vapor. These radiometric observations have been combined in several instances with moisture values measured in the upper troposphere by the standard radiosonde network. In each instance, the result is a much more consistent analysis showing increased spatial detail that agrees with the radiometric observations and does not compromise the conventional data. The improved moisture analyses show relatively dry and moist tongues that are very difficult or impossible to infer from the conventional data alone.

Steranka, J.↗