IV-B-6. Maintenance Station L. E. Livingston Spacecraft Design Div. Some maintenance of the SPS will be necessary from time to time. Propellant must be replenished periodically. Trouble-free thirty-year lifetimes for moving parts such as control moment gyros, antenna joints, star trackers, etc. are unrealistic. Comparatively reliable items such as solid state electronic components will experience random failures. Other problems, e.g., chafing of conductors, may be considered during design but frequently are fully resolved only with operational experience. The maintenance question has not been explored to any depth in this study, however, and the following represents a cursory consideration of the problem. To minimize the payload of the maintenance spacecraft, as many facilities as possible should be incorporated into the SPS. These would include a normally unmanned, habitable control station, some repair and small spares storage facilities, and servicing and local transportation vehicles. To facilitate troubleshooting, a central control station will provide status information on all subsystems. Insofar as feasible, all control equipment, computers, etc. will be located within this control station. The station will be connected to the habitation module. A repair shop and airlock will be connected to the habitation module. It will provide bench repair facilities, storage for small spares, and berthing for servicing and local transport vehicles. These vehicles, as well as the habitation and shop modules, will be derivatives of those used in the construction phase to avoid duplicate development programs. Many maintenance tasks, particularly those occurring on a more or less regular basis (e.g., propellant replenishment), can be planned for shirtsleeve operation from a maintenance vehicle with manipulators. Some electronic components can be located within the maintenance station. However, many repair operations will require dexterity not available from a manipulator; for these, extravehicular activity will be necessary. Most work of this type can be expected to require broad general capability but relatively little detailed subsystem knowledge. Thus, only part of the crew need be EVA-trained, and most of the subsystems experts can operate entirely in a shirtsleeve environment. Based on the above, a minimum maintenance crew might consist of two pilot-astronauts, a maintenance chief, two general EVA technicians, two propulsion technicians, two microwave/electronic technicians and one guidance technician, or a total of ten crew members. A detailed analysis has not been performed, but it is possible that the desired degree of
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