MLI and is to be thick enough so that, in conjunction with the MLI, it provides sufficient meteoroid protection. Docking: o The international docking system (ASTP) type is assumed for POTV stage to payload module docking. o POTV stage-to-stage docking system design is assumed as a multiple probe/drogue system w’th latching at stage O.D. MISSION DEFINITIONS The POTV LEO to GEO mission is assumed to be initiated at the LEO orbit transfer operation base or early in the program, the Shuttle at LEO operational altitudes (200 to 500 km). Modular POTV elements are docked together and propellants tanks topped off. A two-burn injection places the POTV and payload on the final synchronous transfer ellipse with a trip time of 8 to 9 hours. At apogee the circularization maneuver is performed and rendezvous accomplished with the GEO site. GEO orbital stay for a typical mission is between 2 and 7 days. Orbital stay time can be extended for GEO refueling applications. Return to the LEO base is all-propulsive. Mission delta-velocity budgets for the main propulsion system are tabulated for the common stage POTV in Tables VI-E-1, VI-E-2, and VI-E-3 for these modes: GEO satellite maintenance sortie, GEO crew rotation/resupply (both stages refueled at LEO), and GEO crew rotation/ resupply (stage 1 refueled at LEO, stage 2 refueled at GEO). Servicing/ refurbishment is accomplished at LEO, and refueling is done by artificial gravity from orbital storage tanks (in the operational phase). POTV PAYLOADS Three different payloads have been characterized for POTV: crew rotation passenger module, station resupply module, and crew module for a geosynchronous sortie (optional). Geosynchronous Sortie Crew Module - Possibly the first payload to fly with the POTV would be the crew module required for a manned geosynchronous sortie. A reference mission may consist of a 4 man crew performing 1 week of satellite maintenance operations, visiting four satellites with transfers up to 15° longitude between each satellite visit. Additionally, sortie GEO missions may be required during the SPS test program. A crew module concept from the Boeing FSTSA study is shown on Figure VI-E-1 and its associated weight estimate presented in Table VI-E-4. DDT&E and TFU costs of the crew module have been estimated at $365M and $34M, respectively. Crew Rotation Passenger Module - For the operational program phase, crew rotation is expected to occur at least every 6 months in
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