at the rate of two additional power satellites annually. The Reference Design system includes two alternative power satellite configurations, based upon either silicon (Si) photovoltaic cells or gallium aluminum arsenide (GaAlAs) photovoltaic cells.* Since the construction equipment, the manpower requirements for construction, and the gross mass for each power satellite are different for each of these options, the transportation systems required for each option also differ. Both options are discussed below and are summarized in Table 2-2. Earth Launch Facilities. All Earth launch operations are conducted from expanded facilities at Cape Canaveral, Florida. These facilities must include at least two launch pads for Heavy-Lift Launch Vehicles (HLLV) and four launch pads for Personnel Launch Vehicles (PLV). These facilities must also support a fleet of three to five HLLVs; five or six PLVs; 9 to 23 Cargo-Orbital Transfer Vehicles; five to seven Personnel Orbital Transfer Vehicles; and 80 sortie vehicles. Assuming 75% use factors, the launch facilities must be capable of handling annual propel- lant masses on the order of 4 x 10 metric tons of liquid oxygen, 1 x 10 T of liquid methane, and 0.2 x 10 T of liquid hydrogen. This translates to a daily handling capacity of about 10 cubic meters of cryogenic propellants, or enough to fill a sphere 25 meters in diameter. Earth-to-LEQ Vehicles. Cargo is transported from Earth to LEO by two-stage winged HLLVs in a vertical-takeoff-horizontal-landing (VTOHL) configuration. The booster is propelled by 16 high-pressure oxygen-methane engines (vacuum thrust = 9.8 x 10 newtons each) and the orbiter by 14 Space Shuttle main engines (SSME; vacuum thrust = 2.1 x 10 newtons each). The HLLV at takeoff stands 161.1 meters high. The landing weights of the booster and orbiter are 934 and 453 T, respectively. Personnel are transported from Earth to LEO by two-stage winged PLVs, also in a VTOHL configuration, the booster propelled by four high-pressure oxygen-methane engines (vacuum thrust = 9.6 x 10 newtons each) and the orbiter by 3 SSME. The orbiter expends on each flight an external oxygen-hydrogen tank weighing about 25 T. The PLV at takeoff stands 93.6 meters high. The landing weights of the booster and orbiter are 259 and 179 T, respectively. Passenger capacity is 75 per *See Section 2.4 below for descriptions of the alternative power satellite configurations.
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