The configuration arrangement and characteristics of the system elements used in the transfer of each satellite module are shown in figure B-27. Each module is 2.7 x 5.4 km. Six of the modules are transferred without a microwave antenna attached. Their mass is 8700 metric tons each. The other two modules each have a fully constructed microwave antenna attached making their mass 23,700 tons each. Propulsion for the orbit transfer is provided by a combination of electric powered ion thrusters (argon propellant) and LO2/LH2 thrusters. The ion thrusters provide most of the orbit transfer energy whereas the chemical system is used to counteract gravity gradient torques on the module and to maintain desired attitude during the transfer. Power for the ion thrusters is provided by partially deployed SPS solar array. The 8,700-ton modules require 13% of the SPS array deployed to power four panels of 600 ion thrusters. The heavier modules (with antenna) require 36% of the on-board solar array to power four panels of 1,600 ion thrusters. The trip time for each module is 180 days. The SPS solar array was oversized 5% to compensate for the radiation degradation of the silicon solar cells during passage through the Van Allen radiation belt. This also compensates for the inability to anneal out all of the damage after reaching GEO. L. Operations 1. Satellite System Construction Operations - The integrated construction, maintenance and transportation operational concept for low earth orbit (LEO) construction of the CR=1 photovoltaic satellite is shown in figure B-28. Space operations crews and all hardware and consumables required in space are delivered to LEO by launch vehicles. The crew launch vehicle was assumed to be an improved space shuttle with the solid rocket boosters replaced by a reusable liquid propellant booster. The cargo vehicle is a two-stage wing-wing vehicle capable of delivering approximately 400,000 Kg of payload per flight. Crew flights occur every two weeks while three cargo vehicle flights are required every two days to each construction facility for the case of constructing one 10 GWe satellite per year.
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