Showing papers by "Goddard Space Flight Center published in 1970"
TL;DR: In this paper, solid-liquid partition coefficients between phenocrysts and the host lavas have been measured for rare-earth elements by an isotope dilution technique and the consistency of much of the data suggests that most of the phenocryst crystallized under equilibrium, or quasi-equilibrium, conditions.
720 citations
TL;DR: Partition coefficients for K, Rb, Sr, and Ba distributed between plagioclase, K-feldspar, clinopyroxene, orthopyroxenes, mica, hornblende, garnet, and olivine phenocrysts and their igneous matrix materials, have been determined by a mass-spectrometric stable isotope dilution technique.
527 citations
TL;DR: In this article, rare earth element concentrations in zircons and apatites separated from dacites and granites have been measured, and the rare earth patterns of zirons from granites appear to reflect patterns of the liquid phase at earlier stages of crystallization.
337 citations
TL;DR: Geomagnetic tail configuration during substorms from Imp 4 magnetic field and auroral index measurements as discussed by the authors was used to estimate the geomagnetic properties of the Earth's magnetic field.
Abstract: Geomagnetic tail configuration during substorms from Imp 4 magnetic field and auroral index measurements
265 citations
TL;DR: The steady state plasmapause corresponds to the stagnation streamline in the E×B drift in the equatorial plane of the solar wind and the magnetosphere as discussed by the authors, and the model computations indicate that the spatial configuration of the plasmasphere can be very complex, especially near the bulge.
Abstract: The ambient plasma in the equatorial plane is predominantly subject to the E×B drift. By approximating the earth's magnetic field by a dipole, characteristic steady state streamlines in the equatorial plane are determined, assuming the interaction between the solar wind and the magnetosphere is characterized by a constant electric field directed from dawn to dusk in the equatorial plane. The steady state plasmapause corresponds to the stagnation streamline in this flow. If the magnitude of the dawn-dusk field is suddenly increased, the plasmasphere bulge moves toward the sun. By suddenly decreasing the magnitude of this field, the bulge can be made to corotate with the earth. The model computations indicate that the spatial configuration of the plasmapause can be very complex, especially near the bulge, because its position depends upon the past history of the magnetosphere.
208 citations
TL;DR: An analysis of magnetic field measurements in the geomagnetic tail from Explorers 33 and 35 during 1967-1968 has shown that there is a broad region of depressed field magnitude approximately 12 RE thick and centered on the neutral sheet.
Abstract: An analysis of magnetic field measurements in the geomagnetic tail from Explorers 33 and 35 during 1967–1968 has shown that there is a broad region of depressed field magnitude approximately 12 RE thick and centered on the neutral sheet. The solar magnetospheric Bz component is proportionately larger within that region than outside of it. Bz is found to decrease with distance from the earth but to be positive on the average within the depressed field region out to a distance of 70 RE, indicating that although for short periods of time the neutral line may be closer to the earth than the orbital distance of the moon, on the average it is beyond that distance. A negative Bz component was found in ⅔ of the measurements outside the depressed field region. This analysis has shown that the magnetotail field diverges from the tail axis with distance from the earth. This result, together with the Bz observations, supports a geometry in which for large |Zsm| the tail field is diverging in the Zsm as well as the Ysm direction, but is converging slightly toward the neutral sheet within the depressed field region. The combination of expanding tail and reconnection at the neutral sheet can account for the observed tail field magnitude gradient. The Explorer 33 and 35 measurements also indicate that the average angle between the tail axis and the earth-sun line is 3.1°±1.5°.
183 citations
TL;DR: In this paper, the magnetic and thermal pressure of the solar wind were analyzed for the period June to December, 1967, and the 3-hr averages showed that the most probable value of β≡P petertoddk/P petertoddB is β=1.0±0.1.
Abstract: Explorer 34 solar wind data for the period June to December, 1967 show that(a) The magnetic pressure, P
B≡B
2/8π, and thermal pressure,P
k≡n
p
kTp+n
α
kTα+n
e
kTe,are variable and positively correlated on a scale of ≳ 2 days, but (b) changes in P
b and P
k are anticorrelated on a scale ∼ 1 hr (∼0.01 AU). Thus, dynamical hydromagnetic processes (dv/dt⊄o) must occur on the mesoscale, but the solar wind tends to be in equilibrium(P
B+P
K∼constant) on a smaller scale, the microscale. The 3-hr averages show that the most probable value of β≡P
k/P
B is β=1.0±0.1, which implies that the most probable state of the solar wind at 1 AU is not one of equipartition between the thermal energy and magnetic energy. The average total pressure for a given bulk speed(P(V)=P
k+P
k+P
B) is essentially independent of V, implying that P is not determined by the heating or acceleration mechanisms of the solar wind; the average pressure is P=(2.9±1.5)×10-10dyne/cm2.
183 citations
TL;DR: Conditions on Earth would be as hostile as on Venus if the Earth were closer to the Sun by only 6–10 million miles, according to scientists.
Abstract: Venus atmosphere and surface conditions, describing temperature, accumulation of carbon dioxide and runaway greenhouse effect
174 citations
TL;DR: In this article, the spatial distribution of energy deposited by auroral electrons in upper atmosphere, using Monte Carlo method, was analyzed using a Monte Carlo approach. And the results showed that
173 citations
TL;DR: In terms of the relative abundance of K, Rb, Cs, Sr and Ba, modern oceanic and island-arc basalts may be viewed as a gradational family ranging from alkali basalt (enriched in these elements) to low-K-tholeiite, such as ocean-floor basalt as mentioned in this paper.
TL;DR: Evidence for a new component of isotropic γ-radiation above 1 MeV energy being distinct in nature and origin from that at lower energies is presented, consistent only with the hypothesis previously discussed5,6 that theseγ-rays are the redshifted remnant of cosmic-ray interactions producing pions at an earlier stage in the evolution of the universe corresponding to a redshift z≃100.
Abstract: Critical test of cosmological pion decay hypothesis for origin of isotropic gamma radiation above 1 MeV
TL;DR: In this article, the equivalence of Eu2+ and Sr interphase partitioning permits the calculation of the Eu 2 and Eu 3+ concentrations in each of any two equilibrated phases of known Sr and rare-earth concentrations.
01 Jun 1970
TL;DR: The phase boundary compositions of the two-and three-phase fields are listed and compared with the three binary diagrams in this article, and nineteen isotherms were determined in this study.
Abstract: In order to provide the necessary phase equilibria data for understanding the development of the Widmanstatten pattern in iron meteorites, we have redetermined the Fe-Ni-P phase diagram from 0 to 100 pct Ni, 0 to 16.5 wt pct P, in the temperature range 1100° to 550°C. Long term heat treatments and 130 selected alloys were used. The electron microprobe was employed to measure the composition of the coexisting phases directly. We found that the fourphase reaction isotherm, where α+ liq ⇌ γ+ Ph, occurs at 1000° ± 5°C. Above this temperature the ternary fields α+ Ph + liq and α+ γ+ liq are stable and below 1000°C, the ternary fields ⇌+ γ + Ph and γ + Ph + liq are stable. Below 875°C a eutectic reaction, liq → γ + Ph, occurs at the Ni-P edge of the diagram. Altogether nineteen isotherms were determined in this study. The phase boundary compositions of the two-and three-phase fields are listed and are compared with the three binary diagrams. The α + γ + Ph field expands in area in each isotherm as the temperature decreases from 1000°C. Below 800°C the nickel content in all three phases increases with decreasing temperature. The phosphorus solubility in α and γ decreases from 2.7 and 1.4 wt pct at 1000°C to 0.25 and 0.08 wt pct at 550°C. The addition of phosphorus to binary Fe-Ni greatly affects the α/α + γ and γ/α + γ boundaries below 900°C. It stabilizes the α phase by increasing the solubility of nickel (α/α +γ boundary) and above 700°C, it decreases the stability field of the γ phase by decreasing the solubility of nickel(@#@ γ/α + γ boundary). However below 700°C, phosphorus reverses its role in γ and acts as a γ stabilizer, increasing the nickel solubility range. The addition of phosphorus to Fe-Ni caused significant changes in the nucleation and growth processes. Phosphorus contents of 0.1 wt pct or more allow the direct precipitation ofa from the parent γ phase by the reaction γ ⇌ α + γ. The growth rate of the α phase is substantially higher than that predicted from the binary diffusion coefficients.
TL;DR: In this article, the cosmic γ-ray spectrum below 1 GeV arising from cosmic ray p-p interactions is calculated and its characteristics are determined by the properties of secondary neutral pion production occurring at accelerator energies.
Abstract: The cosmic γ-ray spectrum below 1 GeV arising from cosmic ray p-p interactions is calculated. Its characteristics are determined by the properties of secondary neutral pion production occurring at accelerator energies. A model is chosen for numerical calculations in which the two dominant modes of neutral pion production at accelerator energies are the production of the Δ (1.238) isobar and one fireball. The effect of α-p and p-α interactions on the cosmic γ-ray spectrum is also calculated. The final results are given in terms of both differential and integral γ-ray energy spectra.
TL;DR: In this paper, simple two fluid solar wind speed and proton temperature model, discussing non-thermal energy dissipation is presented, and the model is extended to include the nonthermal dissipation of solar energy.
Abstract: Simple two fluid solar wind speed and proton temperature model, discussing nonthermal energy dissipation
TL;DR: In this article, the authors measured distributions of hydrogen and helium thermal positive ions in duskside magnetosphere and showed that the irregular structure and position indicated by measured distribution of hydrogen, helium, and other ions in the magnetosphere can be inferred.
Abstract: Plasmapause irregular structure and position indicated by measured distributions of hydrogen and helium thermal positive ions in duskside magnetosphere
TL;DR: Type 3 solar radio bursts observed at low frequencies for half rotation, discussing occurrence, drift rates, propagation time and emission as discussed by the authors. But they did not specify the type of radio bursts they were emitting.
Abstract: Type 3 solar radio bursts observed at low frequencies for half rotation, discussing occurrence, drift rates, propagation time and emission
TL;DR: Results of recent analyses of metre-wave measurements place the brightness I x of the isotropic component at about one-third the minimum total brightness observed at a frequency f of 100 MHz.
Abstract: Extragalactic LF background radiation spectra, using model for free-free absorption in galactic disk
TL;DR: In this article, the authors present a thermal emission spectra of earth and atmosphere from IR Michelson interferometer onboard Nimbus 3 satellite, which they use to study the Earth and atmosphere.
Abstract: Thermal emission spectra of earth and atmosphere from IR Michelson interferometer onboard Nimbus 3 satellite
TL;DR: The design of the instrument including the optical layout, the phase locked loop operation of the Michelson motor, and the functioning of the reference interferometer are discussed and the methods of data reduction and in-flight calibration are demonstrated on sample spectra recorded while in orbit around the earth.
Abstract: Michelson IR interferometer spectrometer /IRIS/ design calibration and performance onboard Nimbus 3 satellite, demonstrating data reduction and inflight calibration
TL;DR: Magnetosphere thermal ion density and temperature in dawn and morning quadrants from OGO 5 satellite measurements from NASA's Earth Science Data System (ESDS) were obtained by OGO-5 satellite measurements.
Abstract: Magnetosphere thermal ion density and temperature in dawn and morning quadrants from OGO 5 satellite measurements
TL;DR: Magnetic field fluctuations in magnetosheath of Explorer 34 spectral data on sunward earth hemisphere were studied in this paper, showing that magnetic fields fluctuate with magneto-temperature.
Abstract: Magnetic field fluctuations in magnetosheath of Explorer 34 spectral data on sunward earth hemisphere
TL;DR: In this paper, the Earth radiation balance /net flux/ determination from satellite measurements of long wave radiance and reflected solar radiation in upper atmosphere was performed from satellite observations of the Earth's upper atmosphere.
Abstract: Earth radiation balance /net flux/ determination from satellite measurements of long wave radiance and reflected solar radiation in upper atmosphere
01 Jan 1970
TL;DR: The GSFC-NASA Ba release experiments have produced high-latitude observations of 23 ion clouds in the auroral zone and 12 in the polar cap region as discussed by the authors, which can be used to draw conclusions about the nature of the ionospheric electric fields and the tensor conductivity elements that are most effective in producing ionosphere currents.
Abstract: High latitude magnetic disturbances and accompanying auroral displays are obvious evidence of the release of large amounts of energy, presumably from the magnetosphere and magnetotail regions. Until recently experimental efforts towards understanding these phenomena were directed toward measurement of magnetic fields, energetic particles, optical emissions, and the morphology of the observables. The importance of ionospheric and magnetospheric electric fields was recognized in theoretical studies, but actual measurements were not available due to the lack of suitable techniques. In the past several years valid electric field measurements have been made from sounding rockets and satellites with long antennas (Aggson, 1969; Maynard and Heppner, 1970). Another method more suited for making E field observations simultaneously at several points and for extended times at a given location was developed at the Max Planck Institut (Foppl et al., 1967). Barium vapor released from a sounding rocket above about 150 km partially ionizes and produces a visible ion cloud during twilight which can be tracked photographically. The ion cloud drifts under the influence of the electric and magnetic fields, and it can be shown that the velocity of a small cloud above 200 km altitude is given essentially by v = E x B/B 2. Inverting this equation to E= - v x B, the measurement of v in a known magnetic field B gives E. The GSFC-NASA Ba release experiments have produced high latitude observations of 23 ion clouds in the auroral zone and 12 in the polar cap region. From these observations we can draw conclusions about the nature of the ionospheric electric fields and the tensor conductivity elements that are most effective in producing ionospheric currents. The measurements also test the usual assumption that the surface magnetic disturbance is explained by ionospheric currents. From ground based magnetometers a typical equivalent ionospheric current pattern for the polar cap and auroral zone disturbance can be inferred. Figure 1 shows a diagram illustrating the essential features. Our E field investigations have sampled four regions of interest: (a) in the westward electrojet or negative magnetic bay region, (b) in the eastward electrojet region, (c) in the transition region where the westward electrojet passes polewards of the eastward jet, and (d) in the polar cap region. Visible auroral displays were observed in the Ba release region or close by, in all flights except those in the polar cap where auroras were seen only near the southern horizon.
TL;DR: Cosmic ray energy loss in interplanetary medium, discussing solar wind effects on low energy particles was discussed in this article, where the authors considered the solar wind effect on low-energy particles.
Abstract: Cosmic ray energy loss in interplanetary medium, discussing solar wind effects on low energy particles
TL;DR: In this article, a rocket-borne quadrupolecular mass spectrometer was used for positive ion composition measurements by using the downleg and upleg data of the U.S.D region.
Abstract: D region positive ion composition measurements by rocket-borne quadrupole mass spectrometer, discussing downleg and upleg data