Work modules are used for operations, maintenance, and training. They are similar in design to crew modules but have specialized functions which include clinic, satellite components maintenance and checkout, and new personnel training. Base subsystems include electrical power and flight control systems. The total power requirement estimated for all LEO base operations is 3725 kw. The primary power supply is solar arrays similar to those used in the SPS with nickel hydrogen batteries used for occultation periods. The flight control system includes guidance/navigation/attitude type sensors such as IRU, star trackers, horizon sensors and the propulsion system (LO^/LHp to perform attitude and orbit maintenance maneuvers. Construction Base GEO - The GEO construction base is a 2 x 2 baywide platform that is attached to and indexed across the solar array side of the modules, as shown in figure B-32. This platform has four solar array deployment machines that are used to deploy the undeployed solar arrays. There are also a variety of crane/manipulators, logistics and SPS maintenance equipment aboard. The first operation to occur once the modules reach GEO is that of the berthing (or docking) of the modules. The modules are berthed along a single edge as indicated in figure B-33. The major equipment used to perform these berthing operations are shown. The concept employs the use of four docking systems with each involving a crane and three control cables. Variations in the applied tension to the cables allows the modules to be pulled in, provide stopping control and provides attitude control system involving thrusters which are not shown. During the transfer from LEO to GEO, the antenna is attached below the module with a single hinge line. Once GEO is reached, the antenna is rotated into position followed by the final structural and electrical connections, as indicated in figure B-34.
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