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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 955 records · Page 53
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NASA NTRS1976

On the interpretation of Fe II emission profiles in Seyfert galaxies and QSOs

Recent high-resolution spectral scans of several QSOs and Seyfert galaxies show broad Balmer lines and permitted Fe II lines in emission. It is suggested that a careful comparison of the Fe II and Balmer profiles may distinguish between the different proposed mechanisms for broadening of the lines. For a suprathermal-particle model, the hydrogen and Fe II lines arise in the same region, with the Fe II emission produced by the dense ambient gas that is excited by the flux of suprathermal particles. Hence, such a model predicts that the Fe II lines are substantially narrower than the hydrogen lines.

Ptak, R.↗
NASA NTRS1976

Lunar perturbations in columnar electron content and their interpretation in terms of dynamo electrostatic fields

Both the sun and the moon exert influences on the ionosphere, causing fluctuations in its electron content. The small lunar effects, though not negligible, are difficult to analyze because their periodicities differ little from the periodicity of the dominant solar effects. A finite duration impulse response filter was perfected, permitting the efficient splitting of our columnar electron content data into a solar, a lunar, and a residual component. The solar component plus the lunar component and the solar component alone were processed by a dynamic ionospheric simulation program that yields values of vertical plasma drifts when electron content data are used as input. The difference between the two plasma drifts so obtained was taken as being the plasma drift caused by the electric field generated by the lunar tides in the dynamo region. This technique appears to be the first to allow a direct estimation of the lunar-induced electric fields in the ionosphere.

Bernhardt, P. A.↗
NASA NTRS1976

An alternative interpretation of Jupiter's 'plasmapause'

It has recently been suggested that Io is an important source of ions for the plasma detected by Pioneer 10 in the inner magnetosphere of Jupiter. Assuming this to be true, we show that near the orbit of Io the central collector of the Pioneer-10 plasma instrument could detect only inwardly diffusing ions created at a radial distance greater than that of the spacecraft. The rapid decrease in ion density observed beyond Io's orbit is attributed, at least partially, to this effect and thus may not represent a real plasma boundary such as a 'plasmapause'. Instead, the drop in observed ion density could correspond to a decrease in the density of Io-associated neutral particles orbiting Jupiter.

Neugebauer, M.↗
NASA NTRS1976

On the interpretation of least squares collocation

A demonstration is given of the strict mathematical equivalence between the least squares collocation and the classical minimum variance estimates. It is shown that the least squares collocation algorithms are a special case of the modified minimum variance estimates. The computational efficiency of several forms of the general minimum variance estimation algorithm is discussed. It is pointed out that for certain geodetic applications the least square collocation algorithm may provide a more efficient formulation of the results from the point of view of the computations required.

Tapley, B. D.↗
NASA NTRS1977

Interpretation of high-resolution spectra of Mars. IV - New calculations of the CO abundance

Recent measurements of the half-widths of lines, pressure broadened by CO2 at a temperature of 200 K, in the 0-2 band of CO are used to reestimate the amount of CO in the atmosphere of Mars. Assuming an air-mass factor of 3.5, the amount of CO in a vertical path through the Martian atmosphere is estimated to be approximately 5.6 cm-atm. A comparison of CO and O2 abundances indicates that there is about 3.4 times as much molecular oxygen on Mars than expected. It is suggested that the extra oxygen may come from photodissociation of water.

Young, L. D. G.↗
NASA NTRS1976

A simulation study of earth radiation budget data interpretation

The paper describes a simulation of a filtering analysis which yields radiation distributions, measured by a wide-field-of-view radiometer on board an earth satellite, on a scale smaller than the field of view of the instrument. Mathematical models are developed to represent an orbiting wide-field-of-view radiometer to provide simulated measurement data. The simulated measurements are analyzed by a data inversion technique to obtain estimates of the radiation heat fluxes at the top of the atmosphere. By comparing the estimated field to a real radiation field, the effects of directional model errors and sampling strategies are revealed.

Smith, G. L.↗
NASA NTRS1977

Interpretation of spatial and temporal variations of hydrogen quadrupole absorptions in the Jovian atmosphere observed during the 1972 apparition

Results are reported for a systematic investigation of temporal and spatial variations of hydrogen quadrupole lines formed in the Jovian atmosphere, which was performed by measuring the strengths of the S(1) lines of H2 (3,0) and (4,0) quadrupole bands at several points on the Jovian disk during the 1972 apparition. The observations support the hypothesis that the strength of the (3,0) S(1) line varies significantly with time, suggest the possibility of short-term temporal variation in the strength of the (4,0) line, and indicate that the H2 line strengths vary remarkably little from limb to limb in the equatorial region. A Galatry line-shape profile is calculated, and a radiative-transfer analysis is carried out using the Henyey-Greenstein phase function for single particle scattering. It is shown that the observations are consistent with a multilayer atmospheric model having an optically thin upper cloud deck separated by a stratum of nonscattering gas from an optically thick lower cloud.

Hunt, G. E.↗
NASA NTRS1977

Interpretation of observed cosmic microwave background radiation

It is argued that the 'surface of last scattering' of the observed microwave background radiation corresponds to the distribution of dust in galaxies or protogalaxies with a temperature of about 110 K at the epoch corresponding to Z roughly equal to 40. This is in contrast with the plasma temperature of over 3,000 K at an earlier epoch (Z greater than about 1,000), as given by the canonical model of big bang cosmologies. In view of this, the claim that the microwave background radiation lends strong support to hot big bang cosmologies is without foundation.

Alfven, H.↗
NASA NTRS1976

Microcracks, micropores, and their petrologic interpretation for 72415 and 15418

Lunar samples 72415 and 15418 have complex microstructures that indicate a series of fracturing and healing events. Both samples contain relatively few open microcracks but many sealed and healed microcracks. Dunite 72415 contains abundant healed cracks that formed tectonically, symplectic intergrowths spatially and probably genetically related to microcracks, and a cataclastic matrix that has been extensively sintered. Metamorphosed breccia 15418 contains many post-metamorphic healed cracks, large shock induced cracks that have been sealed with glass, and a few younger, thin, open shock induced cracks.

Richter, D.↗
NASA NTRS1976

Subsolidus reduction phenomena in lunar norite 78235 - Observations and interpretations

Lunar rock 78235 is a coarse-grained strongly shocked cumulate norite consisting of about equal proportions of chromian bronzite and anorthite. A study of the rock has revealed the presence in the partly maskelynitized plagioclase of oriented sets of metallic iron rods, what appear to be sets of oriented transparent anisotropic iron-bearing silicate rods and disseminated hard aluminum-rich domains. It is suggested that the apparent nonopaque rods might have the hollandite structure and contain Fe(+3), while the Al-rich domains could represent iron-depleted regions in the plagioclase.

Sclar, C. B.↗
NASA NTRS1977

Interpretation of the silver L X-ray spectrum

Analysis of the Ag L-series X-ray spectrum has been performed, based on relaxed-orbital relativistic transition-energy calculations. Satellite energies were computed in intermediate coupling. It is found that satellites arising from LN double-hole states generally fall within the natural width of the parent diagram lines. Contrary to previous assumption, the observed high-energy satellites are due to LM double-hole states produced by L1-L3M4,5 Coster-Kronig transitions and by shakeoff. The observed peak structure in the satellite spectrum is due to multiplet splitting of the initial and final double-hole states. Theoretical L1-L3M4,5 transition rates based on the Coster-Kronig energies computed by Chen et al. (1977) are closer to experiment than previous results, but still are too large by a factor of about 2, indicating an as-yet undetected flaw in the theory.

Chen, M. H.↗
NASA NTRS1977

Satellite measurements of ionic concentrations applied to low altitude incoherent scatter interpretations

The determination of ion and electron temperatures and electron density from incoherent scatter radar data has in the past involved assumptions concerning the ionospheric composition below 250 km. Using a very large data base of measurements of O(+), O2(+), NO(+), and N2(+) made by the Atmosphere Explorer C satellite, a model has been developed of the ionic concentration between 130 and 300 km as a function of solar zenith angle. As the effect of the new model is to increase the radar determinations of the temperature, this may explain previous discrepancies between Langmuir probe and incoherent scatter temperatures, where the comparisons have been made at these low altitudes

Torr, M. R.↗
NASA NTRS1977

Observations and interpretation of the infrared spectrum of HD 44179

Infrared spectra of HD 44179 have been obtained for the 3040-, 1150-, and 890-kayser emission features. The strengths of the features put constraints on the possible constituents of the materials responsible for each emission feature. The 3040-kayser feature can be due to emission either from a solid (if it arises from a different region than the 890-kayser feature) or from a gas-phase molecule. The 8-13-micron spectrum is fitted with a simple model employing carbonates plus a dielectric in emission and silicates in absorption. It is suggested that amorphous carbon is the dielectric responsible for the featureless underlying continuum.

Bregman, J. D.↗
NASA NTRS1977

Construction and interpretation of a digital inertia image

An image representing the thermal inertia in the vicinity of Pisgah Crater and Lavic Lake in Southern California has been generated from visible, near IR, and thermal images taken from aircraft. Construction of the thermal inertia image required radiometric calibration and geometric rectification of the acquired images as well as registration to a topographic map. The Kahle thermal model used in the construction of the thermal inertia image requires specification of albedo, topographic slope and slope azimuth, diurnal temperature range and local meteorological conditions. Albedo information was derived from the visible image; digital topographic information was computed from digitized stereo aerial photographs; and thermal ranges were calculated by subtracting the predawn from the afternoon thermal image data. Our computed values of thermal inertia were in close agreement with published values for similar surface materials. Thermal inertia provides complementary information to conventional images of reflected solar radiation for use in lithologic mapping.

Gillespie, A. R.↗
NASA NTRS1977

Significance of vegetation in interpreting thermal radiation from a terrestrial surface

The regions between crop rows are modeled as infinitely long diffuse cavities. Geometrical view factors are calculated, accounting for reflected radiation emanating internal to the cavity and from the background sky. A 'cavity' emissivity dependent on local geometry is defined to allow for correcting apparent temperatures to true temperatures. The total emissivity appropriate for correcting aircraft thermal data is then calculated by averaging all emissivity components to account for soil, crop, and background. It is shown that even for the lowest crop and vegetation emissivities, if the crop height-to-spacing ratio is greater than unity, the composite emissivity is greatly increased, giving rise to a decreased error in remotely sensed temperature data.

Sutherland, R. A.↗