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  • 1
    Publication Date: 2013-08-31
    Description: Long term observations of relativistic electrons in the earth's outer magnetosphere show a strong solar cycle dependence with a prominent intensity maximum during the approach to solar minimum. This population therefore closely corresponds to the presence of high speed solar wind streams emanating from solar coronal holes. Using a numerical code, the precipitating electron energy deposition in the earth's upper and middle atmosphere were calculated. Observed events (typically persisting several days) would have maximum effect in the 40 to 60 km altitude range with peak energy depositions greater than 110 keV/cu cm-s. It is suggested that this electron population could play an important long term role in modulating lower D region ionization and middle atmospheric ozone chemistry. Methods are described of observing middle atmospheric and lower ionospheric effects of the electrons including balloon, riometer, and space-based ozone sensor systems. A particularly promising approach may involve the monitoring of global Schumann resonance modes which are sensitive to global changes in the properties of the earth-ionosphere cavity. Present work indicates that Schumann resonance properties are moderately correlated with the flux of precipitating relativistic electrons thus offering the possibility of continuously monitoring this aspect of magnetosphere-atmosphere coupling.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, volume 27; p 217-219
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  • 2
    Publication Date: 2013-08-31
    Description: A microcomputer-based expert system is being developed at the Aerospace Corporation Space Sciences Laboratory to assist in the diagnosis of satellite anomalies caused by the space environment. The expert system is designed to address anomalies caused by surface charging, bulk charging, single event effects and total radiation dose. These effects depend on the orbit of the satellite, the local environment (which is highly variable), the satellite exposure time and the hardness of the circuits and components of the satellite. The expert system is a rule-based system that uses the Texas Instruments Personal Consultant Plus expert system shell. The completed expert system knowledge base will include 150 to 200 rules, as well as a spacecraft attributes database, an historical spacecraft anomalies database, and a space environment database which is updated in near real-time. Currently, the expert system is undergoing development and testing within the Aerospace Corporation Space Sciences Laboratory.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA, Marshall Space Flight Center, Foruth Conference on Artificial Intelligence for Space Applications; p 457-465
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  • 3
    Publication Date: 2013-08-31
    Description: For abstract, see A82-35542
    Keywords: GEOPHYSICS
    Type: ATR-82(7883)-1 , NAS 1.26:169532 , NASA-CR-169532
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  • 4
    Publication Date: 2013-08-31
    Description: Research conducted on auroral electrodynamic coupling between the magnetosphere and ionosphere-atmosphere in support of the development of a global scale kinetic plasma theory is reviewed. Topics covered include electric potential structure in the evening sector; morning and dayside auroras; auroral plasma formation; electrodynamic coupling with the thermosphere; and auroral electron interaction with the atmosphere.
    Keywords: GEOPHYSICS
    Type: NASA-CR-173078 , NAS 1.26:173078 , SSL-83(7951)-4
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  • 5
    Publication Date: 2013-08-31
    Description: Under the simple postulate that multiple large scale detachable magnetospheric convection eddies can exist in the vicinity of the convection reversal boundary and in the polar cap, by Kelvin-Helmholtz instability or otherwise, it is shown that a number of seemingly disconnected plasma and electric field observations in the polar cap can be organized into a theory of magnetosheath and plasmasheet plasma intrusion into the polar cap. Current theory of inverted V structures then predicts existence of similar, but weaker, structures at the eddy convection reversal boundaries in the polar cap. A possible consequence is that the polar cap auroras are natural offshoots from discrete oval arcs and evidently are formed by similar processes. The two arc systems can occassionally produce an optical image in the form of the theta aurora.
    Keywords: GEOPHYSICS
    Type: NASA-CR-170377 , ATR-83(7951)-1 , NAS 1.26:170377
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  • 6
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations and theoretical interpretations of auroral plasma distributions have led to a spectacular advance, in the latter part of the 1970's, in understanding the formation of auroral arcs and the role that the aurora plays in the coupling between the magnetosphere and ionosphere in the evening sector. The key to this understanding is the verification of the existence of electric field components parallel to the magnetic field. The parallel electric field accelerates electrons downwards to form the aurora. At the same time, it accelerates ionospheric ions upwards to provide the magnetosphere with a new source of hot plasma. The auroral plasma observations indicate that the hot auroral plasmas behave according to laws of adiabatic motion coexisting with a measure of plasma turbulence. Theoretical considerations of auroral arc formation are in accord with this plasma characteristic.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Polar Ionospheric X-ray Imaging Experiment (PIXIE) is an X-ray multiple-pinhole camera designed to image simultaneously an entire auroral region from high altitudes. It will be mounted on the despun platform of the POLAR spacecraft and will measure the spatial distribution and temporal variation of auroral X-ray emissions in the 2 to 60 keV energy range on the day side of the Earth as well as the night. PIXIE consists of two pinhole cameras integrated into one assembly, each equipped with an adjustable aperture plate that allows an optimum number of nonoverlapping images to be formed in the detector plane at each phase of the satellite's eccentric orbit. The aperture plates also allow the pinhole size to be adjusted so that the experimenter can trade off spatial resolution against instrument sensitivity. In the principal mode of operation, one aperture plate will be positioned for high spatial resolution and the other for high sensitivity. The detectors consist of four stacked multiwire position-sensitive proportional counters, two in each of two separate gas chambers. The front chamber operates in the 2–12 keV energy range and the rear chamber in the 10–60 keV range. All of the energy and position information for each telemetered X-ray event is available on the ground. This enables the experimenter to adjust the exposure timepostfacto so that energy spectra of each X-ray emitting region can be independently accumulated. From these data PIXIE will provide, for the first time, global images of precipitated energetic electron spectra, energy inputs, ionospheric electron densities, and upper atmospheric conductivities.
    Type of Medium: Electronic Resource
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  • 8
    Publication Date: 2011-08-19
    Description: A model of oval and polar cap arc configurations has been formulated by combining the theory of antiparallel magnetic merging and theories of the evening discrete arc and of the morningside arc systems. Aside from incorporating the verified and yet-to-be-verified predictions of the individual component theories this unified model leads to definite predictions of not only arc configurations but also characteristics of the plasmas that produce the various types of arcs. The model predicts two types of polar cap arcs characterized by the plasma sources: the magnetosheath arc and the plasma sheet arc. Their occurrence should be governed by the By component of the interplanetary magnetic field, and the same type should not occur simultaneously in both hemispheres.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 5153-515
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  • 9
    Publication Date: 2011-08-19
    Description: Energetic particle data from electrostatic analyzers aboard the S3-3 satellite indicative of a downward parallel electric field at low altitudes are presented to argue for a causal connection between downward parallel electric fields and ion heating. The data include observations of upward field-aligned electron beams in regions where precipitating electron fluxes are suppressed. Evidence of downward acceleration of ions and locally mirroring ion conics is also presented. It is argued that the presence of a downward electric field may have important consequences for ion conic heating and might in fact be required for the observed heating of ions to several hundred electron volts.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 4205-421
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  • 10
    Publication Date: 2011-08-18
    Description: Previously announced in STAR as N83-74905
    Keywords: GEOPHYSICS
    Type: Space Science Reviews (ISSN 0038-6308); 35; July 198
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