Showing papers by "Goddard Space Flight Center published in 1968"
TL;DR: In this paper, an electron of a given energy moving in a monoenergetic, isotropic radiation field is considered and the energy spectrum of the photons that are scattered by the electron has been calculated both exactly and in a greatly simplied approximate form suitable for astrophysical calculations.
Abstract: We consider an electron of a given energy moving in a monoenergetic, isotropic radiation field. The energy spectrum of the photons that are scattered by the electron has been calculated both exactly and in a greatly simplied approximate form suitable for astrophysical calculations. The approximation may be derived either by expanding the exact solution in a small parameter and keeping only the leading terms or by employing a simplifying physical approximation at the beginning of the calculation. The approximate spectrum is similar to one previously derived by Ginzburg and Syrovatskii, the principal difference being that the present one does not break down if $\ensuremath{\hbar}{\ensuremath{\omega}}_{1}Eg{({m}_{e}{c}^{2})}^{2}$, where $\ensuremath{\hbar}{\ensuremath{\omega}}_{1}$ is the initial photon energy and $E$ the electron energy. We indicate the astrophysical applications of our approximate spectrum by calculating the spectrum of photons scattered by electrons with an inverse-power-law energy distribution.
355 citations
TL;DR: In this article, a detailed calculation of the lifetime and attentuation mean free path of high-energy cosmic rays against photomeson production is presented. But the results of the calculation are limited to the case of photomesons and the implications of the result are discussed.
Abstract: We have made a detailed calculation of the lifetime and attentuation mean free path of high-energy cosmic rays against photomeson production. The calculation utilized the results of recent laboratory studies of photomeson production which have become available since 1966. The implications of the result are discussed.
285 citations
TL;DR: The Explorer 33 satellite was launched July 1, 1966 and was injected into a highly elliptical earth orbit, and the first 8 orbits of Explorer 33 (July 1 to November 11, 1966) mapped the earth's magnetosheath and magnetic tail from the western flank of the bow shock to the eastern flank as discussed by the authors.
Abstract: The Explorer 33 satellite was launched July 1, 1966 and was injected into a highly elliptical earth orbit. The Goddard Space Flight Center magnetic field experiment onboard the spacecraft consists of a triaxial fluxgate sensor with a maximum dynamic range of ±64 gammas and a sensitivity of ±0.25 gamma along each axis. Because of the initial apogee-earth-sun angle of 118° west of the sun, the first 8 orbits of Explorer 33 (July 1 to November 11, 1966) mapped the earth's magnetosheath and magnetic tail from the western flank of the bow shock to the eastern flank. This mapping of the geomagnetic tail out to 80 earth radii established that the tail extends beyond the lunar orbital distance. Explorer 33 has also found that the earth's bow shock is still a detectable boundary between the interplanetary magnetic field and the downstream magnetosheath at a geocentric distance of 75.7 earth radii. The measurements have further suggested that the cross section of the geomagnetic tail is probably not cylindrical and have shown that the magnetic field magnitude in the tail decreases with distance down the tail from the earth.
217 citations
TL;DR: In this paper, the authors describe and analyze the following micro-scale structures which were found in combined interplanetary magnetic field and plasma data obtained by the deep-space probe Pioneer-6: (1) Several types of simultaneous discontinuities in the magnetic fields and plasma parameters; (2) at least one clear example of a transitional region (D-sheet) associated with a plasma discontinuity; (3) other D-sheets which give evidence of magnetic field annihilation; inhomogeneous isothermal regions in which the square of the magnetic-field intensity is proportional to the
Abstract: This report describes and analyses the following micro-scale (≲.01 AU) structures which were found in combined interplanetary magnetic field and plasma data obtained by the deep-space probe, Pioneer-6: (1) Several types of simultaneous discontinuities in the magnetic field and plasma parameters; (2) at least one clear example of a transitional region (D-sheet) associated with a plasma discontinuity; (3) other D-sheets which give evidence of magnetic-field annihilation; (4) inhomogeneous isothermal regions in which the square of the magnetic-field intensity is proportional to the density; (5) periodic variations in the magnetic-field intensity which are associated with discontinuities in the bulk speed. It is suggested that small velocity discontinuities play a fundamental role in reducing stresses in the interplanetary medium, and that large-velocity discontinuities may give rise to waves and turbulence.
203 citations
TL;DR: In this article, the authors postulate electric field acceleration mechanism beyond 3 earth radii for ambient thermal plasma electrons, based on high latitude electron bursts observed by OGO 4, and postulate that the acceleration mechanism is beyond 3 Earth radii.
Abstract: High latitude electron bursts observed by OGO 4, postulating electric field acceleration mechanism beyond 3 earth radii for ambient thermal plasma electrons
159 citations
01 Jan 1968
TL;DR: A solar system elements abundance compilation based on carbonaceous chondrites and nucleosynthesis in stars is described in this article. But the compilation is based on a single image and is limited to the solar system.
Abstract: Solar system elements abundance compilation based on carbonaceous chondrites and nucleosynthesis in stars
157 citations
01 Jan 1968
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.
138 citations
TL;DR: A way to extract ATP from bacteria by using the unique solvent properties of n-butanol, which is used to determine the ATP content per cell of 19 species of bacteria.
132 citations
TL;DR: Relativistic electron gas in strong magnetic field, obtaining equation of state with quantum theory as discussed by the authors, was used to obtain the Eq. 1.1.0.0
Abstract: Relativistic electron gas in strong magnetic field, obtaining equation of state with quantum theory
132 citations
TL;DR: In this paper, it was shown that the electron energization was caused by the electric fields associated with some static 4-kev potential difference in the magnetosphere, which is known to exist and have been measured directly.
Abstract: Rocket-borne observations were made of a nearly monoenergetic beam of electrons in association with a prebreakup auroral display. The characteristic energy of this beam was about 4 kev and was very stable over a 150-second period of time. The nature of this energy spectra strongly suggests that the electron energization was by the electric fields associated with some static 4-kev potential difference in the magnetosphere. A model in which this potential was established directly along a magnetic field line cannot be uniquely excluded by these observations but is discounted on other grounds. The alternative is a model in which the required electric field is transverse to the magnetic field lines. Such electric fields are known to exist and have been measured directly. Energization of low-energy electrons by an electric field of this geometry, would appear to require that these electrons be stably trapped on closed lines of magnetic force, the energization occurring by virtue of gradient and line curvature drift across equipotential lines. It is this process, which is similar to that proposed by Taylor and Hones (1965), that is believed to have produced the auroral particles observed in this aurora. The electrical potential differences known to be available in the magnetosphere although sufficient to produce these 4-kev electrons are inadequate to produce the 100-kev electrons seen in association with the aurora, thus implying the existence of more than one acceleration mechanism.
130 citations
TL;DR: Perturbations of interplanetary magnetic field by lunar wake compared with disturbed solar plasma flow as mentioned in this paper showed that the magnetic field was perturbed by the lunar wake and solar plasma flows.
Abstract: Perturbations of interplanetary magnetic field by lunar wake compared with disturbed solar plasma flow
TL;DR: In this article, high energy trapped electrons at high and low altitudes, noting energy dependence for attaining equilibrium after magnetic storm, were analyzed and compared with the magnetic storm in a magnetic field.
Abstract: High energy trapped electrons at high and low altitudes, noting energy dependence for attaining equilibrium after magnetic storm
TL;DR: Plasmasphere behavior during solar flare events compared with satellite data from storm-time and plasmapause was studied in this article. But the results were limited to the case of solar flares.
Abstract: Plasmasphere behavior during solar flare events compared with satellite data from storm-time and plasmapause
TL;DR: X rays emitted by energetic vacuum spark, discussing pinch in plasma of evaporated anode metal as discussed by the authors, discussed pinch in plasminar metal and discussed pinch on anode.
Abstract: X rays emitted by energetic vacuum spark, discussing pinch in plasma of evaporated anode metal
01 Jan 1968
TL;DR: Partition coefficients between natural melts, as represented by igneous matrix material, and amphibole, augite, olivine and plagioclase phenocrysts have been determined for eight rare-earth elements and barium by a mass-spectrometric stable-isotope-dilution technique as mentioned in this paper.
Abstract: Partition coefficients between natural melts, as represented by igneous matrix material, and amphibole, augite, olivine and plagioclase phenocrysts have been determined for eight rare-earth elements and barium by a mass-spectrometric stable-isotope-dilution technique. Peridotite nodules, crystallization of plagioclase and relationships between basalts are briefly discussed in terms of the partition coefficient data.
TL;DR: In this article, the authors discuss the interstellar matter effect on composition and diffusion effect necessary to study radiation models, and discuss the effect of cosmic ray propagation on the composition of the universe.
Abstract: Cosmic ray propagation, discussing interstellar matter effect on composition and diffusion effect necessary to study radiation models
TL;DR: In this article, rare earth abundance data for mafic and plagioclase phenocrysts and their igneous matrix materials indicate that Eu anomalies, while caused by the relative stability of divalent Eu, are controlled largely by crystal-chemistry rather than by the redox conditions in the melt.
TL;DR: Induced magnetic moment of magnetized Fermi gas, noting change in magnetic nature with variations in electron density as mentioned in this paper, was found to be a function of variations in the electron density.
Abstract: Induced magnetic moment of magnetized Fermi gas, noting change in magnetic nature with variations in electron density
01 Sep 1968
TL;DR: Unified form of Lambert theorem for elliptic, hyperbolic, and parabolic orbits based on selecting independent variable and normalized time of flight parameter was proposed in this article for the first time.
Abstract: Unified form of Lambert theorem for elliptic, hyperbolic, and parabolic orbits based on selecting independent variable and normalized time of flight parameter
TL;DR: The first direct spectral measurements and time histories, made outside the magnetosphere, of solar-flare electrons having relativistic velocities are presented in this paper, where the 3- to 12-MeV electrons have kinetic energies about two orders of magnitude higher than those solar electrons previously studied in space, and measurements of both the time histories and energy spectra for a number of events in the present solar cycle were carried out.
Abstract: Observations of interplanetary relativistic electrons from several solar-flare events monitored through 1964 to mid-1967 are presented. These are the first direct spectral measurements and time histories, made outside the magnetosphere, of solar-flare electrons having relativistic velocities. The 3- to 12-MeV electrons detected have kinetic energies about two orders of magnitude higher than those solar electrons previously studied in space, and measurements of both the time histories and energy spectra for a number of events in the present solar cycle were carried out. These measurements of interplanetary electrons are also directly compared with solar X-ray data and with measurements of related interplanetary solar protons.
TL;DR: Stable isotope dilution method used to determine lanthanides in six basalts of central Japan is described in this paper, where the authors use stable isotopes dilution to identify the lanthanide in these basalts.
TL;DR: In this paper, the experimental results obtained from the Explorer 35 spacecraft indicate that a detached bow shock wave does not exist in the vicinity of the moon and that the flow conditions near the moon do not resemble those near the magnetosphere of the earth.
Abstract: The experimental results obtained from the Explorer 35 spacecraft indicate that a detached bow shock wave does not exist in the vicinity of the moon. Thus, the flow conditions near the moon do not resemble those near the magnetosphere of the earth. The solar‐wind flow around the moon is treated theoretically as a free‐molecule flow of guiding‐center plasma. Analytical results are obtained to describe the ion flow in the vicinity of the moon. The disturbed region forms a long wake in the downstream of the moon. The thickness of the wake, measured perpendicular to the plane of the solar‐wind velocity and the interplanetary magnetic field, is constant at one lunar diameter. On the other hand, the width of the wake, measured parallel to that plane, increases with distance from the moon.
TL;DR: In this paper, it was suggested that electron temperatures in the E -region are greater than neutral gas temperatures by several hundred degrees, and that these temperatures reflect nitrogen vibrational temperatures of about 3100°K, provided by the reaction which quenches metastable 1 D oxygen atoms produced by photodissociation of oxygen in the Schumann-Runge continuum.
TL;DR: In this paper, a comparison of simultaneous magnetic field measurements by Pioneer 7, Explorer 28, and Explorer 33 satellites is presented, where the authors compare the performance of the three satellites.
Abstract: Comparison of simultaneous magnetic field measurements by Pioneer 7, Explorer 28, and Explorer 33 satellites
TL;DR: Cosmic ray anisotropy direction during solar proton events compared with concurrent interplanetary magnetic field vector direction, using Pioneer 6 data as mentioned in this paper, using Pioneer data sets.
Abstract: Cosmic ray anisotropy direction during solar proton events compared with concurrent interplanetary magnetic field vector direction, using Pioneer 6 data
TL;DR: In this article, the authors compared the results of binary-encounter approximation with available experimental data on the noble-gas and alkali-metal atoms, and found that these predictions agree with observation to within a factor of 2 or 3, and are as reliable as comparable results for electron ionization.
Abstract: Ionization of atoms by proton impact, as predicted by the classical binary-encounter approximation, is examined and compared with available experimental data on the noble-gas and alkali-metal atoms. The results indicate that these predictions agree with observation to within a factor of 2 or 3, and are as reliable as the comparable results for electron ionization. Comparisons are made between electron and proton ionization cross sections. The proton ionization curves all have a single maximum and are otherwise monotonic, in contrast to electron ionization, where the effects of atomic shell structure produce secondary maxima for some atoms. The effect of averaging over bound-state speed distributions is discussed, and is found to be much less important for protons than for electrons, except at very low proton energies. The need for experimental measurements at higher energies (\ensuremath{\sim}10 MeV) is discussed.
TL;DR: In this article, it was shown that the distribution of lanthanides is quite different between enstatite single crystal and polycrystalline material, and that the difference can also bring about a great difference in efficiency of enrichment of calcium in remnant liquid.
Abstract: Lanthanide concentrations in 13 fractions of the Norton County achondrite have been determined by a mass spectrometric isotope dilution method. A most remarkable fact is that the distribution of lanthanides is quite different between enstatite single crystal and polycrystalline material. This difference is interpreted in terms of different formation processes. It is thought that in the growth of single crystals, individual ions were placed one by one to build a strictly defined lattice structure, whereas the polycrystalline material was produced by the transitional formation of amorphous phases or phases of low crystallinity resulting from spontaneous cohesion of neighboring ions in the melt. The lanthanide patterns for single crystal fractions are grossly similar to each other, but there is some variation between them in fine structure of the patterns. This can be interpreted as a reflection of the fact that the partition of lanthanides into single enstatite crystals is more or less sensitive to rather subtle differences in the conditions of crystal growth. The genesis of Shalka, Johnstown (both hypersthene achondrites) and eucritic achondrites can be interpreted in terms of the precipitation of single crystals only. A great difference in partition coefficient between single crystals and polycrystalline material system appeares to be of much petrological significance, because it is thought that the difference can also bring about a great difference in efficiency of enrichment of calcium in remnant liquid. Irregular behavior of Cc, Eu, and Yb in a few single-crystal fractions was ascertained by independently processed redeterminations. The irregularities may be ascribed to single crystals favoring higher valence state of these elements relative to the melt. It is suggested that lanthanum might have been a little depleted relative to the other lanthanides in the initial melt that produced Norton County.
TL;DR: Graphite grain formation in cool stars examined on basis of molecular equilibrium data for stellar atmospheres was examined in this paper. But the results were limited to a single star and were not applicable to other stars.
Abstract: Graphite grain formation in cool stars examined on basis of molecular equilibrium data for stellar atmospheres
TL;DR: In this article, the general problem of obtaining an acceptable estimate of a spectrum in Fourier spectroscopy is discussed for four specific cases, and two known techniques currently used for the spectral recovery from an asymmetric interferogram are shown to be mathematically equivalent.
Abstract: The general problem of obtaining an acceptable estimate of a spectrum in Fourier spectroscopy is discussed for four specific cases. The two known techniques currently used for the spectral recovery from an asymmetric interferogram are shown to be mathematically equivalent. A discussion of their practical merit is also included.
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TL;DR: The asteroid 197 (Arete) approaches asteroid 4 (Vesta) within 0.04 astronomical unit once every 18 years and it may be possible to determine the mass of Vesta from observations of Arete, according to the indicated uncertainty being a probable error.
Abstract: The asteroid 197 (Arete) approaches asteroid 4 (Vesta) within 0.04 astronomical unit once every 18 years. It may therefore be possible to determine the mass of Vesta from observations of Arete. From 72 observations a value of (1.20 ± 0.08) x 10-10 solar mass was derived, the indicated uncertainty being a probable error.