I. Mass Statement A summary of the satellite mass properties is presented in Table 1. The masses are separated into three major segments: solar array, microwave antenna, and array antenna interfaces (the section of satellite between the array and antenna which includes the rotary joint, sliprings, and antenna yoke). The GaAlAs configuration utilizes a concentration ratio of 2 which reduces the required blanket area and in turn the blanket mass. The antenna section mass properties are the same for both options. The antenna mass is dominated by the transmitter subarray which includes the klystrons and waveguides. The other large items are the power distribution system and the thermal control system for the klystrons and DC/DC converters. The total mass for the two options, including a 25% contingency factor, is 34 and 51 million kilograms for the GaAlAs and silicon options, respectively. J. Space Transportation This section provides descriptions of the reference space transportation system vehicles. The alternative concepts from which the Reference System was selected are described in Appendix A. The vehicles are distinguished by their primary payload, either cargo or personnel, and their area of operations between earth and low earth orbit (LEO) or between LEO and geosynchronous earth orbit (GEO). Cargo is transported from the earth's surface to LEO by the HLLV and personnel (and priority cargo) are transported from earth to LEO and back by the PLV. fransportation between LEO and GEO is provided by the COTV and the POTV. The general groundrules followed in the development and evaluation of the transportation system are: • The SPS transportation system elements, with the possible exception of shuttle derived PLV's, are dedicated and optimized for the installation, operation, and maintenance of the SPS. • The SPS transportation system will be designed for minimum total program cost.
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