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Summary POLICY ASSUMPTIONS l. The United States will have a sustained manned space launch capability. 2. The present shuttle will have to assure that function at least until the turn of the century. 3. An ELV production commitment will be made to achieve a mixed tleet of launchers. FLIGHT RATES Three Orbiters can sustain a rate of tt to l0 flights per year after an initial buildup period ot approximately 2 years providing: (l) no Orbiter is lost or becomes inoperable, (2) adequate logistics support exists, and (3) no problems exist that require extensive downtime. A surge rate of lZ flights per year should be possible for short periods of time for simple payloads and flight plans. With a t-Orbiter fleet the sustainable flight rate would be l1-13 per year with a surge rate of l5 flights per year only if appropriate ground support facilities are acquired. In order to sustain such rates and take account of possible contingencies, the shuttle scheduling should be based upon fewer vehicles than are actually in the inventory by almost one Orbiter. FLEET CONCEPT If the space shuttle is to serve manned launch requirements tor an extended period of time, then it should be viewed in terms of a fleet in the same manner as other transportation systems and consideration must be given to vehicle attrition necessitating replacement Orbiters over time. This will necessitate a balance between production rates and replacement requirements. l5
Ito LAUNCH DEMAND With the temporary cessation of shuttle flights, it is expected that the backlog of manifested payloads will actually decrease as some previously scheduled satellites will not be flown and the DoD will off-load many payloads for launch on ELVs. The heaviest launch demand arises for the Space Stationâ32 shuttle launches are anticipated during the 3-year construction phaseâand, presuming schedules ao not slip, this could not in itself be accommodated by 3 Orbiters. This situation is recognized by NASA study groups currently reexamining the configuration of the Station. While many military payloads are slated for launch on the Titan IV and the MLV, there is not an ELV launch capability to accommodate the large number of space science or commercially contracted payloads. A resolute ELV procurement effort by NASA, or other civil government agency, is not yet in place but may be required to fulfill commercial contracts ana NASA's space science program. Unless or until a commercial launch vehicle industry comes into existence, however, an extensive private launch industry is not likely to arise before the l990s. PAYLOAD PARTITIONING Partitioning of payloads between the shuttle and ELVs has been materially affected because NASA is not funded at present to procure ELVs. Even in the short run, some additional off-loading of DoD-related payloads may be in order when alternatives are available.
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