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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Apparent relationship between solar sector boundaries and 300-millibar vorticity: Possible explanation in terms of upward propagation of planetary-scale waves

The correlations between the solar sectors and large-scale atmospheric vorticity in the lower atmosphere reported earlier are of interest since the solar-sector data appear to be independent of any terrestrial influences. It is shown that even these solar data may be affected by geomagnetic properties; a method for removing such influences is suggested.

Deland, R. J.↗
NASA NTRS1975

Evidence for non-radial fields in the sun's photosphere and a possible explanation of the polar magnetic signal

The appearance of H-alpha fibrils suggests the presence of magnetic fields inclined at noticeably nonradial angles in the sun's chromosphere. Evidence is presented to suggest that these angles continue into the photosphere. The presence even of small nonradial inclinations can significantly affect the appearance of regions observed by a longitudinal magnetograph. In particular, a simple bipolar loop can appear unbalanced when viewed near the limb. It is suggested that the observed polar signal may be nothing more than a geometric effect arising when a balanced but systematically aligned array of bipolar pairs is viewed at an angle.

Pope, T.↗
NASA NTRS1976

Explanation for the very low Ga and Ge concentrations in some iron meteorite groups

Parallels between the abundance patterns of moderately volatile elements in iron meteorites and ordinary chondrites are pointed out and discussed in relation to condensation processes in the solar nebula. The discussion is centered around a graph in which As, Cu, Ga, Ge to Ni ratios, normalized to CI chondrites, are compared for IVB, IVA, IVB, and IIIAB irons and H-group ordinary chondrites. The patterns suggest that the same volatile loss mechanism was at work for both IVB irons and ordinary chondrites, but was more efficient in the IVB process. A picture for the process at the IVB location is proposed, according to which condensation occurred when temperature decreased rapidly and trace metals condensed as a fine aerosol that was later blown away by a T-Tauri solar storm. Condensation at the H-group location was more complete because of a less rapid temperature decrease, allowing trace metals to diffuse deeper into Fe-Ni grains. Possible ways in which IVA conditions may have differed from IIIAB or H conditions are also proposed and discussed.

Wasson, J. T.↗
NASA NTRS1977

Geologic investigation of Mercury data and the subsequent mapping and explanation of the quadrangle area H-12

The origin of scraps and ridges mapped in the H-12 region of Mercury are discussed. These features apparently are of non-impact origin and show distinctly non-random patterns of distribution and orientation. These patterns cannot be simply related to selective enhancement of visibility by lighting conditions, global stresses of spin down or interior cooling, or local uplifts or subsidences. Suggestions are made that the origin of these structures may lie outside the region of Mercury photographed or the scarps and ridges may have formed by reactivation of faults or joints bounding pre-existing crystal blocks.

Blasius, K. R.↗
NASA NTRS1977

A possible explanation of the mechanism of formation of the equatorial jet on the surface of Jupiter

Formation of the equatorial jet of the Jovian surface was explained as a consequence of the Taylor-Proudman theorem. The asymptotic theory of motion of low viscosity fluids in a rotating spherical shear layer was included. The model shows the straited structure of the Jovian surface as the outflow of convective cells having the shape of axisymmetric rolls extended along the axis of rotation in the meridional direction. Depth of the layer was found to be of the order of 1000 kilometers.

Yavorskaya, I. M.↗
NASA NTRS1978

Expansion and broadening of coronal loop transients - A theoretical explanation

Consequences are examined of the assumption that an observed coronal loop transient is a twisted rope of magnetic-field lines expanding and broadening in the background coronal plasma and magnetic field. It is shown that the expansion can be accounted for by the azimuthal component of the field; the observed broadening of the loop as it moves outward can be accounted for by the longitudinal component of the field. In order to have a net outward force and at the same time avoid a classical pinch (sausage) instability, the two components of the field must satisfy a certain inequality. It is predicted that, as the loop rises, the width (h) of its top portion should vary proportionally with distance (R) from the sun's center. This is in good agreement with measurements that show h is proportional to the 0.8 power of R. The prediction that the radius of curvature of the top portion of the loop should be proportional to R differs from the measured variation. The difference could be accounted for by a drag due to the background coronal field that flattens the loop's top.

Mouschovias, T. CH.↗
NASA NTRS1975

Lunar anorthosite paradox - An alternative explanation

In most lunar terrae samples a trend of decreasing Ab-content of plagioclase with increasing Fa-content of olivine is observed. This covariance of composition is the opposite of the trend observed in terrestrial layered intrusions, and contradicts Bowen's reaction series. The 'anomalous' trend is considered in terms of olivine-melt and plagioclase-melt equilibria. The composition of plagioclase crystallizing from a melt depends directly upon the activity of silica in the melt, while the composition of olivine does not. It is proposed that the inverse correlation of plagioclase and olivine compositions in most lunar terrae rocks is a predictable consequence of crystallization from a lunar bulk composition which is poorer in silica than the bulk compositions of terrestrial layered intrusions. The data of Roedder and Weiblen (1974) lend support to this hypothesis.

Drake, M. J.↗
NASA NTRS1978

Carbon suboxide polymer, an explanation for the wave of darkening on Mars

The carbon suboxide thermal polymer or its irradiated product is affected by water vapor. The polymerized carbon suboxide simulates the Martian wave of darkening on the inner wall of a glass tube when humidified by passage of water vapor through the tube. The polymer was visibly darkened by the advancing vapor front. With increasing polymer thickness and/or water vapor concentration the wave of darkening similarly intensifies simulating the dark fringe in the Martian circumpolar areas. Surfaces are lightened constantly being renewed by particulate material settling from the atmosphere. It is hypothesized that light and dark areas have polymer coatings, but light areas have small particles which scatter white light more effectively and appear brighter on the surface of Mars.

Oyama, V. I.↗
NASA NTRS1979

Lodestone-explanation for magnetic properties and characterization of the source of magnetic hardening

The microstructure of Class I lodestones was investigated by X-ray diffraction and by optical and transmission electron microscopy, and the behavior of lodestone magnetization was studied at temperatures of 4 to 825 K. It was found that intense magnetization is associated with the gamma Fe2O3-Fe3O4 intergrowth. Thermal demagnetization of the lodestone studied was nearly complete at 300 C. The loss of natural remanence was found to be associated with transformation of gamma Fe2O3 to alpha Fe2O3.

Wasilewski, P. J.↗
NASA NTRS1979

The effects of ultraviolet light on the degradation of organic compounds - A possible explanation for the absence of organic matter on Mars

The analysis of the top layer of the Martian regolith at the two Viking landing sites did not reveal any indigenous organic compounds. However, the existence of such compounds at deeper layers cannot be ruled out. Cosmochemical considerations indicate various potential sources for organic matter on Mars, such as comets and meteorites. The study tested the stability of a sample of the Murchison meteorite and various organic substances which have been detected in carbonaceous chondrites, such as glycine, adenine and naphthalene, to the action of ultraviolet light. The compounds were adsorbed on powdered quartz and on California desert soil and were irradiated in the presence or absence of oxygen. The organic content, before and after irradiation, was measured by carbon elementary analysis, UV-absorption, amino acid analysis or pyrolysis-gas chromatography-mass spectrometry. In the absence of oxygen, adenine and glycine appear to be stable over the given part of irradiation. A definite degradation was noticed in the case of naphtalene and the Murchison meteorite. In the presence of oxygen in amounts comparable to those on Mars all compounds were degraded. The degree of degradation was influenced by the irradiation time, temperature and oxygen content.

Oro, J.↗
NASA NTRS1979

Evidence for the deficiency of short cosmic ray pathlengths and a physically realistic explanation - The no-near-sources model

Recent observations of the charge and energy spectra of cosmic-ray nuclei are used to construct secondary-to-primary charge ratios at the two ends of the charge spectrum. These ratios are found to be inconsistent with the ad hoc leaky-box model of cosmic-ray propagation which leads to an exponential pathlength distribution. Models for which the pathlength distribution function is deficient in short pathlengths provide a more consistent picture. Several of these models, both ad hoc and physical, are investigated. The physical model considered is one for which detailed galactic propagation parameters and boundary conditions are used and for which there exist no near sources of cosmic rays over a time interval corresponding to a few times the cosmic-ray age.

Lezniak, J. A.↗
NASA NTRS1980

Physical explanations of the destabilizing effect of damping in rotating parts

The destabilizing effect of rotating damping was investigated. When the rotation was faster than the whirl, rotating damping drags the orbiting particle forward. When stationary damping was also present, the stability borderline was readily determined by balancing the backward and forward drags. A key notion was that a forward whirl at rate omega a sub n with respect to stationary axes appears to be a backward whirl at rate Omega - omega sub n with respect to a system rotating supercritically at rate Omega. The growth rate of unstable whirls (or the decay rate of stable whirls was readily estimated by a simple energy balance.

Crandall, S. H.↗
NASA NTRS1979

Diverse puzzling asteroids and a possible unified explanation

Recent observations have led to unconventional models of certain asteroids, suggesting previously unsuspected forms. Some of these include binary asteroids (e.g., 532 Herculina, 18 Melpomene), very irregular asteroids (e.g., the Mars-crossing 1580 Betulia), and very elongated asteroids, unlikely to be collisional fragments (e.g., 624 Hector). A connection is suggested between this observational work and ongoing theoretical work concerning collisions of large comparable-sized asteroids. Such collisions have different consequences from the collisions usually considered. The new work suggests possible sources of elongated and binary asteroids.

Hartmann, W. K.↗
NASA NTRS1981

The infrared spectrum of ammonia hydrate - Explanation for a reported ammonia phase

A number of anomalous spectra of solid NH3 deposited from the vapor phase have appeared in the literature. These spectra have been ascribed to a new phase of NH3. In the experiment reported here these anomalous spectra were reproduced by depositing a thin film from a mixture of gaseous NH3 and H2O and annealing this film at a temperature of 162 K. The thin film spectra showed excellent agreement with recent data on NH3.H2O. The anomalous 'NH3' spectra are, therefore, seen to be caused by H2O contamination of solid NH3 with formation of NH3 hydrate.

Still, G.↗
NASA NTRS1980

An explanation for the alternating north-south asymmetry of Io's sodium cloud

The hot Jovian plasma torus discovered by Voyager 1 is responsible for the periodic intensity variations of Io's sodium cloud, which are correlated with Io's magnetic latitude. The plasma torus must be a long-lived phenomenon in spite of its apparent absence at the time of the Pioneer flybys. The hot electrons (100,000 K) must be concentrated about one Jupiter radius from the magnetic equator in order to produce the observed variations. Electron impact ionization in the hot plasma torus is strong enough to form and to maintain Io's ionosphere; the hot plasma torus may be the dominant agent forming the ionosphere. Io's bound atmosphere is dense enough that the plasma torus electrons cannot cause a noticeable variation in its Na emission intensity.

Trafton, L.↗
NASA NTRS1981

A search for a nonbiological explanation of the Viking Labeled Release life detection experiment

The possibility of nonbiological reactions involving hydrogen peroxide being the source of the positive response detected by the Viking Labeled Release (LR) life detection experiment on the surface of Mars is assessed. Labeled release experiments were conducted in the LR Test Standards Module which replicates the Viking flight instrument configuration on analog Martian soils prepared to match the Viking inorganic analysis of Mars surface material to which an aqueous solution of hydrogen peroxide had been added. Getter experiments were also conducted to compare several reactions simultaneously in the presence and absence of UV radiation prior to the addition of nutrient. Hydrogen peroxide on certain analog soils is found to be capable of reproducing the kinetics and thermal information contained in the Mars data. The peroxide concentration necessary for this response, however, is shown to require a chemical stability or production rate much greater than seems likely in the Mars environment. As previous experiments have shown hydrogen peroxide to be the most likely nonbiological source of the positive LR response, it is concluded that the presence of a biological agent on Mars must not yet be ruled out.

Levin, G. V.↗