ROCKWELL SATELLITE POWER SYSTEM (SPS) CONCEPT DEFINITION STUDIES G. M. HANLEY SPS Program Manager Rockwell International Abstract — Evolution of SPS concepts since initiation of the DOE/NASA system studies is described. Early studies included solar thermal, solar photovoltaic, and nuclear concepts, all of which had microwave transmission systems. As a result of these earlier studies, three concepts were considered to be viable SPS candidates: (1) a Rankine solar thermal concept, (2) a silicon solar array photovoltaic concept, and (3) a gallium arsenide (GaAs) solar array photovoltaic concept. The Rockwell effort has since been concentrated on the GaAs photovoltaic concept. The major characteristics of this system are described. Alternatives to this system considered during the past year also are described. A summary is presented of ground and space construction, the space transportation system elements, and the SPS program. INTRODUCTION The Department of Energy (DOE) is currently conducting an evaluation of approaches to provide energy that will meet demands in the post-2000 time period. The Satellite Power System (SPS) is a candidate for producing significant quantities of base-load power using solar energy as the source. The SPS concept is illustrated in Fig. 1 for a solar photovoltaic concept. A satellite, located at geosynchronous orbit, converts solar energy to de electrical energy using large solar arrays. The de electrical energy is conducted from the solar arrays to a microwave antenna. At the microwave antenna, the de energy is transformed to microwave RF energy. A large, 1 km diameter, antenna beams the energy to a receiving antenna (rectenna) on the ground. The rectenna converts the RF energy, at very high efficiency, to de electrical energy which is input to the utility network for distribution. Typically, a single SPS provides 5 GW of power to the utility interface on the ground. Two satellite power systems could provide more power than is needed by large metropolitan areas such as Los Angeles, New York, or Chicago. Because of the large dimensions of the satellite (the solar array area is approximately 75 km2) and the large mass (approximately 35 million kg), it is necessary to construct the satellite on orbit where zero-gravity allows very low structural mass. The ground- located rectenna is nominally an elliptical array 10 km by 13 km. At the earth's surface, the microwave beam has a maximum intensity in the center of 23 mW/cm2 (less than 1/4 the solar constant) and an intensity of less than 0.1 mW/cm2 outside of the rectenna fenceline (10 mW/cm2 is the current United States microwave exposure standard). This paper presents the results of a continuing effort by Rockwell International to provide system definition data to aid in the evaluation of the SPS concept by DOE (1,
RkJQdWJsaXNoZXIy MTU5NjU0Mg==