Magnetic field fluctuations in the earth's magnetosheath
Magnetic field fluctuations in magnetosheath of Explorer 34 spectral data on sunward earth hemisphere
Fairfield, D. H.↗
SEARCH · Engineering Papers
Results for “Data exploration”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Electric field in the magnetosphere as deduced from asymmetries in the trapped particle flux
Magnetospheric electric field configuration from trapped particle flux asymmetries, using Explorer 14 electron data
Hones, E. W., Jr.↗
Internal Structure of the Geomagnetic Neutral Sheet
Models for internal structure of geomagnetic tail neutral sheet deduced from Explorer 34 magnetic data
Ness, N. F.↗
Possible fossil lunar magnetism inferred from satellite data
Fossil lunar magnetism observations, using magnetometer data from orbiter Explorer 35
Binsack, J. H.↗
Lunar electrical conductivity from Apollo 12 magnetometer measurements - Compositional and thermal inferences
Lunar electrical conductivity profile from joint power spectral density analysis of Apollo 12 and Explorer 35 magnetometer data
Colburn, D. S.↗
NASTRAN Benefits Analysis. Volume 1: Executive Summary
The acceptance of NASTRAN, the NASA structural analysis computer program, is explored, based on data from a sample set of users. Baseline data are generated for future comparison of costs and benefits of the program. The impact on, and benefits to, segments of government and industry from current use of NASTRAN are considered. Ways in which potential users may benefit from application of the program to their individual needs are also discussed.
Source record↗
Radio Astronomy Explorer (RAE) 1 observations of terrestrial radio noise
Radio Astonomy Explorer (RAE) 1 data are analyzed to establish characteristics of HF terrestrial radio noise at an altitude of about 6000 km. Time and frequency variations in amplitude of the observed noise well above cosmic noise background are explained on the basis of temporal and spatial variations in ionospheric critical frequency coupled with those in noise source distributions. It is shown that terrestrial noise regularly breaks through the ionosphere and reaches RAE with magnitudes 15 or more db higher than cosmic noise background. Maximum terrestrial noise is observed when RAE is over the dark side of the Earth in the neighborhood of equatorial continental land masses where thunderstorms occur most frequently. The observed noise level is 30-40 db lower with RAE over oceans.
Herman, J. R.↗
Observations of proton spectra (1.0 less than or equal to proton energy less than or equal to 300 keV) and pitch angle distributions at the plasmapause
Detailed proton spectral and pitch angle distribution observations were obtained from two proton detectors and a fluxgate magnetometer flown on Small Scientific Satellite A (Explorer 45). The data of interest are from orbit 99 in-bound occurring on 17 December 1971, some 8 hours prior to the sudden commencement of a magnetic storm. The data are consistent with the initiation of ion cyclotron instability when certain requirements are met. These criteria are met initially at the altitude at which the sudden intensity decrease occurs. However, after the initiation of the instability, the linear theory is unable to explain the further evolution of intensities, pitch angle distributions, and energy spectra of the ring current particles.
Williams, D. J.↗
Radio Astronomy Explorer /RAE/. I - Observations of terrestrial radio noise.
Radio Astronomy Explorer (RAE) I data are analyzed to establish characteristics of HF terrestrial radio noise at an altitude of about 6000 km. Time and frequency variations in amplitude of the observed noise well above cosmic noise background are explained on the basis of temporal and spatial variations in ionospheric critical frequency coupled with those in noise source distributions. It is shown that terrestrial radio noise regularly breaks through the ionosphere and reaches RAE with magnitudes 15 dB and more above cosmic noise background, on frequencies above the F-layer critical frequency.
Herman, J. R.↗
Soft X-ray bremsstrahlung and fluorescent line production in the atmosphere by low energy electrons
The effect of low energy quasi-trapped or precipitating electrons which impact on the counter windows of soft X-ray detectors are discussed. The errors caused by X-rays produced in the residual atmosphere above a rocket-borne detector because of the resemblance to X-rays of cosmic origin are examined. The design and development of counter windows which make it possible to identify the atmospherically produced X-rays are described. Curves are presented to show the following: (1) preliminary low energy electron data from Atmospheric Explorer C, (2) X-ray flux in electron-excited nitrogen and oxygen, (3) typical proportional counter response to low energy cosmic rays, and (4) proportional counter response to X-radiation produced by electrons incident upon a gas of oxygen to nitrogen number of 0.4.
Kraushaar, W. L.↗
Influence of solar wind variability on geomagnetic activity
A statistical study of solar wind data from the Explorer 33 satellite shows that interplanetary magnetic field irregularities are enhanced in the interaction region where a fast solar wind stream overtakes a slower solar wind stream. Comparison with geomagnetic AE and ap indexes further shows that these interplanetary irregularities enhance the level of geomagnetic disturbances. Thus while substorm occurrence is highly correlated with the dawn-dusk component of the solar wind electric field, the amplitude of the substorms is an increasing function of the variance in the interplanetary field. This result can be interpreted as a capacitative effect of the magnetopause that allows a time-varying solar wind electric field to penetrate the magnetosphere more effectively than a static solar wind electric field.
Garrett, H. B.↗
The relationship between velocity gradients and magnetic turbulence in the solar wind
The correlations among the time derivative of the solar-wind velocity, the magnitude of the interplanetary magnetic field (IMF), and the IMF turbulence level are examined to test the idea that interaction between two colliding solar-wind streams can generate turbulence in the solar wind and the IMF. Data obtained by Explorer 33 on the solar wind and IMF are described, and the analysis techniques are outlined. The results indicate that the IMF turbulence level, as measured by the variance, is correlated with the existence of positive velocity gradients in the solar wind. It is noted that while the variance is an increasing function of the field magnitude, it is also independently correlated with the solar-wind velocity gradient.
Garrett, H. B.↗
Advanced planetary studies
Study concepts and planning analyses programs for NASA's solar system exploration are summarized. Data cover manpower/cost estimation research, Jupiter orbiter lifetime analysis, error/control analysis of penetrator deployment at the moon and Mercury, and advanced planning activities.
Source record↗
Bow shock protons in the lunar environment
Protons from the earth's bow shock are observed by the suprathermal ion detector experiment (SIDE) in two regions of the lunar orbit. The dawn region begins at the dawn-side bow-shock crossing and ends about 5 days later, the dusk region begins at about 2 days prior to entering the dusk-side magnetosheath and ends at the inbound bow-shock crossing. Dusk and dawn refer to a terrestrial coordinate system. The dominant contribution to the ion spectra observed by the SIDE in these regions is from particles with energies between about 750 eV/q and 3500 eV/q. Analysis of simultaneous data from the Explorer 35 magnetometer and the SIDE indicates that the observability of bow-shock protons at the lunar distance is dependent on the configuration of the interplanetary magnetic field.
Benson, J.↗
Satellite measurements of ion composition and temperatures in the topside ionosphere during medium solar activity
Information on both ion density and temperature is obtained from analysis of Retarding Potential Analyzer data from the OGO-4 and Explorer-31 satellites. Results obtained from data in the altitude range of 700-2000 km during medium solar activity are presented. An attempt is made to describe the major altitude variations of ion densities and temperatures at middle and low latitudes. The transition heights, where the heavier and lighter ions are equal, are found to be about 1600 and 1300 km at middle and low latitudes, respectively, for daytime and 700 km at night for middle latitudes. Based on the observed data and using diffusive equilibrium as a first-order approximation, topside ionospheric composition models are given for medium solar activity.
Goel, M. K.↗
The aeronomy of odd nitrogen in the thermosphere. II - Twilight emissions
A model developed for the aeronomy of odd nitrogen in the thermosphere is used to analyze rocket measurements of N(4S) and NO densities. Data from Atmosphere Explorer were used to develop a consistent reaction kinetics model for odd nitrogen chemistry. It is concluded that most NO(+) dissociative recombination events must produce N(2D), that N(2D) is quenched by O at a rate of 1 trillionth cu cm per sec, and that the atmospheric O2 quenching rate of N(2D) is consistent with the laboratory rate. The major quenching agent of N(2D) between 140 and 220 km is atomic oxygen, and this reaction is the major source of N(4S). Peak N(4S) densities of about (20-60) million per cu cm at 140-150 km are predicted, with the variability being indicative of the model sensitivity to a factor of 2 change in the O/O2 ratio in the thermosphere.
Strobel, D. F.↗
Ion convection velocity reversals in the dayside cleft
Nearly simultaneous measurements of energetic particle precipitation and vector ion velocity have been made for the first time on Atmosphere Explorer C. These data have revealed the existence of both shear and rotational reversals in the ion convection velocity within the region of dayside cleft particle precipitation. The ion velocity data have shown that substantial regions of the dayside polar cap boundary are nearly electric equipotentials at which cleft particle precipitation is also observed but which cannot be identified with a merging region producing open field lines. Asymmetries in the polar cap flow, first implied by Heppner, may be determined by the extent and location of the equipotential boundaries.
Heelis, R. A.↗
Composition effects in thermospheric gravity waves
Classical linearized gravity wave theory is employed to derive relationships between amplitude ratios and phase angles of atmospheric constituents undergoing acoustic-gravity wave oscillations. These results are compared with recently reported Atmospheric Explorer-C satellite data. Calculated amplitude and phase characteristics, for a large class of pure internal gravity wave oscillations, are in accord with the AE-C satellite measurements.
Dudis, J. J.↗