Satellites are shut down and the solar arrays turned away from the sun during maintenance in order to enhance crew safety. Trade studies concluded that: (1) Satellite maintenance operations should be remove-and-rep lace rather than in-place repair to minimize SPS outage times; (2) Hardware repair at the GEO base pays off in reduced cost for spares acquisition and transportation from Earth. Development of the integrated crew operations concept included consideration of crew safety and well-being. Stay-times in space were restricted to 90 days, based on physiological and psychological considerations. After 90 days in zero-g, a crewperson will require 90 to 180 days on Earth before returning to the zero-g environment. With the exception of crew in-transit between LEO and GEO in a POTV, all personnel are within an hour's transit to a solar flare storm shelter. The POTV is shielded with 5 g/cm^ and can always reach safety in 5 hours or less. Analyses of GEO base operations have estimated a construction and support crew of about 440, including all support and indirect functions. The maintenance operations crew increases year to year as the number of satellites to be maintained increases. The maintenance crew includes equipment repair personnel and their support. The LEO base crew required is roughly 200. Most of the LEO base crew are logistics personnel; a contingent for space-based transportation vehicle maintenance is also provided. An additional increment of crew are provided periodically for construction of electric orbit transfer vehicles. Figure 4 shows the time history of LEO and GEO base crew size. Integrated space operations are highly interrelated as diagrammed in Figure 5. These interrelationships were quantified and used to determine the frequency of operations and total acquisition requirements for all vehicles. Results (for the reference scenario) are shown in Figures 6 and 7. These results are the basis for total space transportation and construction costs, reported in another paper.
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