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Directional Dependence of Counting Rates for Explorer IV (Satellite 1958 Epsilon)

Robert Jordan NaumannUnited States. National Aeronautics and Space Administration

出版	George C. Marshall Space Flight Center, 1963
URL	http://books.google.com.hk/books?id=RWdaET56ZCgC&hl=&source=gbs_api

註釋Inspection of directional scintillation counter data from Explorer IV revealed fluctuations in the counting rate that appeared to be due to the body motions of the satellite and the anisotropy of the radiation flux. It was felt that the body motions and the angular dependence of the radiation flux could be determined from the data available. This work is a description of the methods used and results obtained from this determination. It was found that the counting rate is generally a maximum when the detector axis is normal to the magnetic field which is expected from the theory of particle trapping. The counting rate falls off as the detector axis makes smaller angles with the magnetic field lines, reaching a minimum value when the detector comes within about 40 degrees of the magnetic field lines. Knowledge of this angular dependence of the counting rate will allow calculation of the radiation distribution along a particular magnetic line of force. In the analysis of the rigid body motion, two rather surprising facts were observed. First, the components of the total angular momentum vector of the satellite do not remain constant in a space orientation-fixed reference system, although the magnitude remains essentially constant. Second, the small residual roll of the satellite about its longitudinal axis does not decay monotonically. In fact, at one point, the roll rate was observed to increase by almost an order of magnitude in one day. These two observations suggest that external forces are present and exert body torques on the satellite. It is possible that the origin of the forces may be due to an interaction of a magnetic moment in the satellite with the geomagnetic field, although this is not yet confirmed.