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  • GEOPHYSICS  (54)
  • SPACECRAFT DESIGN, TESTING AND PERFORMANCE  (38)
  • 1975-1979  (92)
  • 1975  (92)
  • 1
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    Drift-free magnetic geometries in adiabatic motion (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: There exist magnetic fields in which particles bouncing between mirror points experience no net first-order guiding center drift. In such fields, even though the instantaneous gradient and curvature drifts are not zero, their total effect integrated over any bounce period vanishes, so that particles merely wobble back and forth around fixed field lines. A class of two-dimensional drift-free fields, somewhat resembling the configuration found in the geomagnetic tail, is described; several proofs of the drift-free property are given, including some that suggest that the property of vanishing net drift might extend to nonadiabatic orbits. A general criterion for identifying drift-free fields is developed, and a case of motion in a nearly drift-free field is also investigated. The theory is applied to the plasma sheet in the earth's magnetotail, and observational evidence is presented suggesting that the magnetic field there indeed approaches a drift-free configuration.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; Nov. 1
    Format: text
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  • 2
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    ATS-6 - Flight performance of the Advanced Thermal Control Flight Experiment (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The Advanced Thermal Control Flight Experiment on ATS-6 was designed to demonstrate the thermal control capability of a thermal diode (one-way) heat pipe, a phase-change material for thermal storage, and a feedback-controlled heat pipe. Flight data for the different operational modes are compared to ground test data, and the performance of the components is evaluated on an individual basis and as an integrated temperature-control system.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: IEEE Transactions on Aerospace and Electronic Systems; AES-11; Nov. 197
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  • 3
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    Auroral electrons and the optical emissions of nitrogen (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Simultaneous rocket measurements of the auroral electron flux and the optical emissions of N2 give a consistent picture of electron impact excitation in an aurora. The electron data show that the incident auroral electrons are nearly monoenergetic with energy about 25 keV. The overall shape of the observed low-energy electron spectrum is in good agreement with other recent observations and also with recent theoretical models, although there is some disagreement with the models in the value of the power law slope above 20 eV. A discussion of the secondary electron spectrum obtained near apogee shows that a single power law cannot accurately describe the secondary electron spectrum in the energy range from 3 to 85 eV. About 40% of the N2(+) 1NG (0,0) band emission at 3914 A is excited by electrons with energy below 85 eV.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; July 1
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  • 4
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    The L equals 6.7 quiet time barium shaped charge injection experiment 'Chachalaca' (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Near dawn on October 9, 1972, UT, a barium plasma injection experiment was carried out from Poker Flat, Alaska, during quiet magnetic conditions (Kp equals 1+). The visible plasma flux tube produced was more diffuse than the flux tubes in previous experiments, but it could be tracked for 30 min out to an altitude of 2.5 earth radii. The flux tube remained integral for about 20 min, when a single striation separated from the main streak. Comparisons of the observed flux tube orientation with theoretical field models show no significant deviations ascribable to field-aligned currents. Cross-field drift rates of the foot of the flux tube indicate an E field of approximately 7 mV/m at 200-km altitude. Although an attempt was made via a jet aircraft flight, barium ions were not detected in the southern conjugate region. No energetic particle precipitation phenomena were observed which could be ascribed to the barium plasma injection.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; July 1
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  • 5
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    Depletion of the F2 region ionosphere and the protonosphere by the release of molecular hydrogen (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Theoretical models have been used to investigate the effects of artificially injected H2 gas on plasma densities in the ionospheric F region and the overlying protonosphere. Owing to large reaction rates between H2 and ionospheric O(+) ions, plasma densities in both daytime and nighttime ionospheres can be greatly reduced by modest amounts of released H2 gas. One hundred kg of H2 released at 300-km altitude reduces local O(+) densities by more than three orders of magnitude and produces about a 5% depression in H(+) densities in the overlying protonosphere. These results suggest that it should be possible to conduct controlled chemical-modification experiments for investigation of many outstanding ionospheric and magnetospheric problems.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 2; Aug. 197
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  • 6
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    Simulation verification techniques study: Simulation performance validation techniques document (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Techniques and support software for the efficient performance of simulation validation are discussed. Overall validation software structure, the performance of validation at various levels of simulation integration, guidelines for check case formulation, methods for real time acquisition and formatting of data from an all up operational simulator, and methods and criteria for comparison and evaluation of simulation data are included. Vehicle subsystems modules, module integration, special test requirements, and reference data formats are also described.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-150933 , MDC-E1136
    Format: application/pdf
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  • 7
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    A search for molecular hydrogen fluorescence near 100 km (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The fluorescence of H2 in the Lyman band system, excited by solar extreme ultraviolet radiation, provides a means for the optical detection of H2 in the upper atmosphere. In particular, the Ly beta line of hydrogen is nearly degenerate with the (6,0) P1 transition, and absorption in this line produces fluorescence in the v-prime = 6 progression, principally at 1265, 1366, 1462 and 1608 A. Absorption by O2 rapidly attenuates the Ly beta from an overhead sun below 100 km and also significantly attenuates the fluorescent radiation. Far-ultraviolet dayglow spectra from 1130 to 1510 A obtained from an Aerobee rocket experiment on 11 December 1972 give an upper limit for any H2 emission which is a factor of 5 higher than expected according to recent hydrogen models.
    Keywords: GEOPHYSICS
    Type: Journal of the Atmospheric Sciences; 32; Nov. 197
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  • 8
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    Attitude control requirements for an earth-orbital solar electric propulsion stage (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Solar Electric Propulsion Stage (SEPS) application in earth orbit requires considerably more maneuvering for thrust vector steering and solar array pointing than planetary missions. Attitude maneuver requirements for geosynchronous and low earth-orbital missions are presented. Situations which result in optimum steering torque requirements exceeding the capability of current SEPS configurations are defined. Sub-optimal steering techniques are defined which reduce the geosynchronous mission torque requirements to acceptable levels with negligible performance penalties. Some low earth-orbital flight regimes with earth shadowing are found to result in much larger torque requirements and impose significant mechanization penalties if serious performance losses are to be avoided. Alternative attitude control mechanization techniques are defined for these cases.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 75-353 , American Institute of Aeronautics and Astronautics, Electric Propulsion Conference; Mar 19, 1975 - Mar 21, 1975; New Orleans, LA
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  • 9
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    Full non-linear treatment of the global thermospheric wind system. I - Mathematical method and analysis of forces. II - Results and comparison with observations (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The equations of horizontal motion of the neutral atmosphere between 120 and 500 km are integrated with the inclusion of all nonlinear terms of the convective derivative and the viscous forces due to vertical and horizontal velocity gradients. Empirical models of the distribution of neutral and charged particles are assumed to be known. The model of velocities developed is a steady state model. In Part I the mathematical method used in the integration of the Navier-Stokes equations is described and the various forces are analyzed. Results of the method given in Part I are presented with comparison with previous calculations and observations of upper atmospheric winds. Conclusions are that nonlinear effects are only significant in the equatorial region, especially at solstice conditions and that nonlinear effects do not produce any superrotation.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 37; Feb. 197
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  • 10
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    Local time variation of equatorial thermospheric composition determined by the San Marco 3 Nace (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The results of the Neutral Atmospheric Composition Experiment (Nace) on the Italian San Marco 3 satellite are analyzed. The analysis provides a comprehensive description of the daily variations in the densities of O, N2, Ar, and He in composition of the lower thermosphere, and also indicates that transport processes (possibly occurring elsewhere in the atmosphere) play an important part in the daily variation of the thermospheric composition at altitudes between 220 and 250 km.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; June 1
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