Showing papers by "Goddard Space Flight Center published in 1969"
TL;DR: Green function solution to the Maxwell equations for interplanetary and coronal magnetic fields above photosphere, considering field at source surface as discussed by the authors, considering magnetic field at the source surface.
Abstract: Green function solution to Maxwell equations for interplanetary and coronal magnetic fields above photosphere, considering field at source surface
1,135 citations
TL;DR: In this paper, it was concluded that the waves are associated with the earth's bow shock since they only occur when projection of the interplanetary field observed at the spacecraft intersects the shock.
Abstract: Fifty orbits of Explorer 34 data have been used to study 0.01–0.05 Hz transverse waves in the interplanetary medium region between the bow shock and the spacecraft apogee of 34 RE. It is concluded that the waves are associated with the earth's bow shock since they only occur when projection of the interplanetary field observed at the spacecraft intersects the shock. The waves are observed 18.5% of the time when a total of 134 days of interplanetary data is considered, but more than 90% of the time when the field has the proper orientation with respect to the bow shock. On the basis of this result it is suggested that these waves with 20–100 second periods are a permanent feature of the solar wind-earth interaction. The transverse component of the waves is typically several gammas in amplitude in 4–8 gamma fields. The disturbance vector in the XY plane generally exhibits the same sense of rotation in a coordinate system where the field is oriented along the positive z axis. Attenuation of wave amplitudes with distance from the bow shock is estimated to be only a factor of 2 when the spacecraft is 15 RE from the bow shock. The absence of waves at particular field orientations, even though the field line intersects the shock, is interpreted as a propagation effect. This observation is the basis for calculations that yield an average velocity in the plasma frame of 2.7 ± 0.4 times the solar wind velocity. Whistler propagation and local generation by two-stream instability are discussed as alternate theoretical explanations for the presence of the waves. It is suggested that the data favor the latter mechanism.
345 citations
TL;DR: In this paper, electric field variations in vicinity of auroral forms from motions of Ba vapor clouds released from Nike-Tomahawk rockets were observed in the vicinity of the Earth's magnetic field.
Abstract: Electric field variations in vicinity of auroral forms from motions of Ba vapor clouds released from Nike-Tomahawk rockets
172 citations
TL;DR: In this article, it was shown that on the mesoscale unique filaments with sharp boundaries containing well-ordered magnetic fields are not always seen although discontinuities are always present at ≈ 1 AU.
Abstract: It is shown that the interplanetary magnetic field has different characteristics on different scales, and it is noted that a given physical theory may not be applicable or relevant on all scales. Four scales are defined in terms of time intervals on which the data may be viewed. Many discontinuities in the magnetic-field direction are seen on the mesoscale (≈ 4 days, ≈ 1 AU). The characteristics of such directional discontinuities which were observed by Pioneer 6 during the period December 16, 1965-January 4, 1966 are presented, with special emphasis on their distribution in time. Previously, it was suggested that such discontinuities are simply boundaries of spaghetti-like filaments extending from the sun to the earth. Here it is shown that on the mesoscale unique filaments with sharp boundaries containing well-ordered magnetic fields are not always seen although discontinuities are always present at ≈ 1 AU. Thus, the interplanetary medium appears to be discontinuous rather than filamentary. The filamentary model implies that discontinuities originate at the sun and are convected with the solar wind. The discontinuous model allows the additional possibility that the discontinuities form in the interplanetary medium far from the sun.
164 citations
TL;DR: In this article, a model equatorial electrojet by spherical harmonic expansion for geomagnetic field was constructed by using spherical harmonic expansions for equatorial equatorial electric vehicles. But the model was not tested.
Abstract: Construction of model equatorial electrojet by spherical harmonic expansion for geomagnetic field
151 citations
TL;DR: In this paper, the problem of multiple scattering by a plane parallel atmosphere with anisotropic phase functions typical of cloud and haze particles was studied and the resulting albedos, angular distributions of intensities, and planetary magnitudes were compared to solutions obtained with approximate analytic phase functions and, in the case of the cloud phase function, to the solution obtained with the forward diffraction peak omitted from the phase function.
Abstract: Solutions are obtained for the problem of multiple scattering by a plane parallel atmosphere with anisotropic phase functions typical of cloud and haze particles. The resulting albedos, angular distributions of intensities, and planetary magnitudes are compared to solutions obtained with approximate analytic phase functions and, in the case of the cloud phase function, to the solution obtained with the forward diffraction peak omitted from the phase function. It is shown that the cloud phase function with the truncated peak yields results practically identical to those obtained with the complete cloud phase function, not only for albedos and magnitudes, but also for the angular distribution; the approximation introduces errors of several per cent in the angular distribution for direct backscattering (the region of the glory), for emergent angles near grazing regardless of the incident angle, and, of course, a larger error occurs for total scattering angles near 0°. However, the errors are unimpor...
150 citations
TL;DR: Olivine and metal compositions of pallasitic meteorites by electron microprobe measurements, obtaining cooling rates as discussed by the authors, were used to obtain the cooling rates of the meteorites.
Abstract: Olivine and metal compositions of pallasitic meteorites by electron microprobe measurements, obtaining cooling rates
131 citations
TL;DR: Power spectra studies of interplanetary magnetic field fluctuations based on data from Pioneer 6 space probe were performed by as mentioned in this paper, where the Pioneer 6 was used for power spectra analysis.
Abstract: Power spectra studies of interplanetary magnetic field fluctuations based on data from Pioneer 6 space probe
126 citations
TL;DR: In this paper, the solar wind discontinuity surfaces observed by spacecraft magnetometers determined from measured time delays and solar wind speed were determined from measurements of the time delay and the wind speed.
Abstract: Solar wind discontinuity surfaces observed by spacecraft magnetometers determined from measured time delays and solar wind speed
116 citations
TL;DR: In this paper, worldwide changes in earth magnetic field determined by examination of magnetic field and interplanetary plasma data for solar wind near the earth near the Earth were determined by examining the magnetic field of the Earth near the Sun.
Abstract: Worldwide changes in earth magnetic field determined by examination of magnetic field and interplanetary plasma data for solar wind near earth
113 citations
TL;DR: A number of events have been studied that provide evidence that relatively small portions of the magnetopause occasionally become severely distorted as mentioned in this paper, usually elongated in the north-south direction, and the magnetosheath magnetic field is usually either nearly parallel or antiparallel to the magnetospheric field.
Abstract: A number of events have been studied that provide evidence that relatively small portions of the magnetopause occasionally become severely distorted. The largest distortions are generally elongated in the north-south direction, and the magnetosheath magnetic field is usually either nearly parallel or antiparallel to the magnetospheric field. As a result, the distortions do not involve severe bending of any magnetic field lines. The distortion is frequently triggered by a change in the properties of the solar wind. A model involving propagation of a thin discontinuity past the earth is consistent with the observations. Observationally, the severe distortions are distinct from the small-scale more or less uniform radial excursion of the magnetopause that are seen on a large fraction of all magnetopause crossings. They are also distinct from the expansions and contractions of the entire magnetosphere in response to changing solar wind pressure.
TL;DR: The magnetic field measurements made by the magnetic field experiment on the IMP 3 (Explorer 28) spacecraft have been examined at the time of geomagnetic s.s.c. events.
Abstract: The magnetic field measurements made by the magnetic field experiment on the IMP 3 (Explorer 28) spacecraft have been examined at the time of geomagnetic s.s.c. events. Thirty-six such events occurred while IMP 3 was in the interplanetary medium during 1965, 1966 and 1967 and have been analysed. Of these events 8 must have been tangential discontinuities, 2 are either tangential discontinuities or rotational discontinuities and 26 are possible shock waves. (Two of these 26 events have been shown by other authors to be shocks.) These 26 possible shocks have similar magnetic signatures: an increase of 20 % or more in the magnetic field magnitude and a relatively small (always less than 90°) change in direction. The larger s.s.c. events were more likely to be caused by possible shocks while the smaller events were often associated with tangential discontinuities. The orientation of the discontinuity surfaces of the 26 possible shocks shows a preference to be aligned somewhere between a direction perpendicular to the sun-earth line and a direction tangent to the local spiral angle of the magnetic field. It was possible to associate solar flares with 14 of the 26 possible shock events. Of these 14, a reliable orientation was deduced for 8 events. By considering the orientation of these 8 events in relation to the position of the parent flares on the solar disk it is suggested that a typical shock front propagating out from the sun has a radius of curvature less than but of the order of 1 AU.
01 Jan 1969
TL;DR: Diffusion-convection theory for solar cosmic ray propagation in interplanetary magnetic field has been proposed in this paper, where the authors show that the theory can be applied to the case of solar cosmic rays.
Abstract: Diffusion-convection theory for solar cosmic ray propagation in interplanetary magnetic field
TL;DR: In this paper, a simple model indicates eclogite or garnet peridotite as the most likely source rocks of alkali and submarine basalts, and the trace element data indicate that plagioclase has had an important effect in modifying composition.
TL;DR: In this article, the Alouette 2 Langmuir probe data were examined for effects due to electron concentration irregularities (fine structure) and the results showed that spread F occurred at the height of the satellite whenever fine structure was observed.
Abstract: Data obtained from the Alouette 2 Langmuir probe experiment during a 3-month period in the fall of 1966 have been examined for effects due to electron concentration irregularities (fine structure). Irregularities occur in patches hundreds of kilometers in horizontal extent, and individual irregularities have amplitudes between 5% (limit of resolution) and 70% and dimensions of less than 2 km along the satellite path. These irregularities appear more often at night than during the day, and they occur in a region that contains the auroral oval and extends to both higher and lower latitudes. Comparison of the probe data with Alouette 2 ionograms obtained simultaneously shows that spread F occurred at the height of the satellite whenever fine structure was observed. However, particularly at mid latitudes, spread F often occurs at the satellite even when the probe does not detect irregularities. When spread F occurs, but the probe does not observe fine structure, the irregularities are less than 5% in amplitude (i.e., below the probe’s resolution). Calculations using an irregularity model indicate that spread F is often caused by irregularities less than 0.5 km thick. Several irregularity production mechanisms that could account for the results are discussed.
TL;DR: In this paper, the photodisintegration of ultra-high energy cosmic rays by universal radiation field is discussed, and the implications on origin and propagation time are analyzed, respectively.
Abstract: Photodisintegration of ultrahigh energy cosmic rays by universal radiation field, analyzing implications on origin and propagation time
TL;DR: In this paper, the authors applied detailed theories of gyro-synchrotron emission and absorption in a magnetoactive plasma, X-ray production by the bremsstrahlung of non-thermal electrons on ambient hydrogen, and electron relaxation in a partially ionized and magnetized gas to the solar flare burst phenomenon.
Abstract: We have applied detailed theories of gyro-synchrotron emission and absorption in a magnetoactive plasma, X-ray production by the bremsstrahlung of non-thermal electrons on ambient hydrogen, and electron relaxation in a partially ionized and magnetized gas to the solar flare burst phenomenon. The hard X-ray and microwave bursts are shown to be consistent with a single source of non-thermal electrons, where both emissions arise from electrons with energies < mc
2. Further-more, the experimental X-ray and microwave data allow us to deduce the properties of the electron distribution, and the values of the ambient magnetic field, the hydrogen density, and the size of the emitting region. The proposed model, although derived mostly from observations of the 7 July 1966 flare, is shown to be representative of this type of event.
TL;DR: Diatomic molecules rotational excitation calculated from electron molecule elastic scattering parameters in fixed nuclei approximation in fixed-nodes approximation was calculated in this article, where the authors used a fixed-node approximation.
Abstract: Diatomic molecules rotational excitation calculated from electron molecule elastic scattering parameters in fixed nuclei approximation
25 Feb 1969
TL;DR: In this article, the parabolic-in-log N lamination method was used to calculate the electron density N versus true height h in the ionosphere provided a number of refinements are introduced.
Abstract: The basic principles of the ionosonde technique for ionospheric electron-density determination are reviewed, with special emphasis on the satellite version. It is shown that the lamination method of data reduction, developed initially for the analysis of ionograms obtained with ground-based ionosondes, can be used to calculate the electron density N versus true height h in the topside ionosphere provided a number of refinements are introduced. These refinements are required because the extraordinary wave data have to be used to obtain N(h) profiles from topside ionograms, and because these data are very sensitive to the magnetic field variation over the great altitude range of topside soundings. A complete procedure for analyzing topside ionograms, based upon a parabolic-in-log N lamination method is presented which incorporates the actual values of the earth's magnetic field at all heights, a change in variable which renders the group path integrand finite at the reflection point, and iteration until successive calculations agree to within 0.01 km. A procedure was also developed to insure and accelerate the convergence of the iteration process. The importance of each refinement is discussed and illustrated quantitatively. It is shown that this new N(h) reduction technique can, in theory, yield topside electron-density profiles with an altitude accuracy of a few kilometers over a 3000 to 400 km altitude range. This theoretical accuracy can be achieved using typically ten to twenty data points per ionogram. In practice, the errors in the N(h) profiles arise primarily from the limited resolution of the ionograms, calibration inaccuracies, and deviations from vertical propagation. The actual accuracy of topside N(h) profiles is discussed in a companion paper [16].
TL;DR: Satellite observations of geomagnetic tail in magnetosphere near midnight meridian plane, discussing formation, shape, plasma sheet and models as discussed by the authors, discussed formation and shape, shape and models
Abstract: Satellite observations of geomagnetic tail in magnetosphere near midnight meridian plane, discussing formation, shape, plasma sheet and models
TL;DR: Explorer 34 observations of hydrogen and He ions in solar wind, noting number density variations and tentative association with geomagnetic storms was made by as mentioned in this paper, who reported that the number of hydrogen ions in the solar wind varied with the number density.
Abstract: Explorer 34 observations of hydrogen and He ions in solar wind, noting number density variations and tentative association with geomagnetic storms
TL;DR: A new value of the solar constant, 135.1 mW cm(-2), has been derived, as well as a revised solar spectral irradiance curve for zero air mass.
Abstract: Solar constant and spectral irradiance curve for zero air mass obtained from aircraft measurements
01 Jan 1969
TL;DR: In this article, rare earth and barium concentrations have been determined by mass-spectrometric isotope-dilution for a chondrite composite, nine calcium-rich achondrites, two plagioclase separates, and two pyroxene separates.
Abstract: Rare-earth and barium concentrations have been determined by mass-spectrometric isotope-dilution for a chondrite composite, nine calcium-rich achondrites, two plagioclase separates, and two pyroxene separates. The brecciated basaltic achondrites have higher (3–17 times) absolute rare-earth and barium concentrations than those in the average chondrite, but similar relative concentrations. Rare-earth and barium data, petrography, and chemistry indicate that the brecciated achondrites cannot be cumulates, to any great extent, of pigeonite or plagioclase, which have fractionated relative rare-earth and barium concentrations. The brecciated achondrites apparently represent liquids, perhaps with different amounts of phenocrystic hypersthene; the closed-system crystallization of the Juvinas achondrite, which is induced from the whole-rock and mineral europium concentrations, strongly supports this interpretation. Hypabyssal or extrusive (rather than plutonic) crystallization is indicated. Measured plagioclase and clinopyroxene partition coefficients for the rare earths and barium place limits on maximum amounts of plagioclase and pigeonite of approximately 20% each that could have been removed from the achondritic magmas.
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01 Apr 1969TL;DR: The measurement of ATP and its response to different compounds can be used to classify sporulation mutants and to localize on the biochemical chart the pathways that may be affected by the mutation.
TL;DR: Simultaneous solution of continuity and heat conduction equations for ionospheric electrons, ions and neutral species for studying F region magnetic storm behavior as mentioned in this paper was used to study magnetic storm behaviour.
TL;DR: In this paper, the authors explore the possible importance of time-dependent convection electric fields as an agent for diffusing trapped magnetospheric radiation inward toward the earth, and derive a one-dimensional diffusion equation to describe statistically the loss-free motion of mirroring particles with arbitrary but conserved values of the first two adiabatic invariants M and J.
Abstract: We explore here the possible importance of time-dependent convection electric fields as an agent for diffusing trapped magnetospheric radiation inward toward the earth. By using a formalism (Birmingham, Northrop, and Falthammar, 1967) based on first principles, and by adopting a simple model for the magnetosphere and its electric field, we succeed in deriving a one-dimensional diffusion equation to describe statistically the loss-free motion of mirroring particles with arbitrary but conserved values of the first two adiabatic invariants M and J. Solution of this equation bears out the fact that reasonable electric field strengths, correlated in time for no longer than the azimuthal drift period of an average particle, move particles toward the earth at a rate at least an order of magnitude faster than electric fields whose source is a fluctuating current on the magnetopause.
TL;DR: The optical design of a Wolter type 1 glancing incidence x-ray telescope for the wavelength region 6-100 A and the results of laboratory and rocket flight tests on a prototype instrument are briefly described.
Abstract: Optical design of Wolter type 1 glancing incidence X ray telescope for 6-100 A wavelength region, describing results of laboratory and rocket flight tests of prototype
TL;DR: Plasmapause position measurements by ion mass spectrometers and broadband VLF receivers on OGO 1 and OGO 3 and by broadband recordings at Antarctica are reported in this paper.
Abstract: Plasmapause position measurements by ion mass spectrometers and broadband VLF receivers on OGO 1 and OGO 3 and by broadband recordings at Antarctica
TL;DR: Cosmic gamma ray spectra from production and decay of neutral pi-mesons produced in metagalactic cosmic-ray proton-proton collisions were collected by as discussed by the authors.
Abstract: Cosmic gamma ray spectra from production and decay of neutral pi-mesons produced in metagalactic cosmic-ray proton-proton collisions