Experimental Objectives The objectives of the High Voltage Solar Array (HVSA) Experiment are listed below in the order of priority: (1) Deploy and retrieve the thin flexible solar array. Obtain the mechanical and dynamical characteristics of the array during each phase. (2) Apply the generated power to the high power experiments at low voltage. (3) Connect the solar cell blocks in series in a successive manner and determine the upper limit of voltage free from surface breakdown, power drain through space plasma, and enhancement of aerodynamic drag. Attitude of SFU or array is the major parameter for this Functional Objective (FO). (4) Demonstrate the power supply capability as versatile PCU by changing the series-parallel connection of all blocks. The output voltage is less than the limitation determined by the third FO. The high power experiments, for which the generated power is applied in the second FO, are the MPD Thruster Experiment and the Space Plasma Experiment. Each FO will be described later in more details. Configuration and Characteristics The system has two solar array wings as shown in Fig. 5. Extendable masts and solar cell blankets are integrated in a monolithic structure, a concept which gives stiffer properties to the system. The length of the wing, when fully extended, is 9.6 m. The key parameter is not the absolute dimensions of the array, but the power, 8 kW or array area. The detailed system study is summarized for the instrument characteristics as follows: Orbital Operation Since the present experiment aims to verify the compatibility of high power/high voltage solar array with the ionospheric environment, it is imperative to implement the test at the time of maximum solar activity. Fig. 6. represents the variation of solar activity with reference to the sunspot area. The next time of maximum activity is 1992. The allowance of launch opportunity is one year. The operation is done in daytime as shown in Fig. 7. The normal surface of the solar array should be directed to
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