VI-E PERSONNEL ORBITAL TRANSFER VEHICLE (POTV) (C. Mac Jones, Future Programs Office) GROUNDRULES AND ASSUMPTIONS Due to the much smaller payload requirements for transporting personnel and high priority equipment than SPS construction cargo to GEO, it is assumed that the POTV is a special purpose device optimized for that function. For the independent chemical propulsion cargo OTV (COTVq) used in the GEO construction of the SPS, it may be possible to delete the development of a POTV and fly the passenger carrying module as part of the large COTVg outbound cargo. This program deletion and possible cost saving may oe addressed in subsequent studies should the GEO construction location and chemical cargo orbit transfer vehicles be selected. In particular for the low Earth orbit (LEO) SPS construction, a dedicated personnel orbital transfer vehicle (POTV[J will be required. For the purpose of the JSC in-house SPS study, the conservative choice is made to employ conventional chemical rocketry with return of the vehicle and crew to low Earth orbit. Information generated by the Future Space Transportation Systems Analysis Study (NAS 9-14323), previous JSC in-house work, and the'extensive Space Tug studies conducted by both NASA and the USAF over the past 5 years are utilized as reference material. The POTV concept deploys from LEO operational altitudes (200 to 500 km) to GEO, and returns all-propulsively to LEO for subsequent rendezvous with an orbiting craft or support facility for refueling and reuse. Other crew return concepts deserve recognition and study such as aeromaneuvering and aerobraking, and winged and ballistic entry modes but are not treated in this study. Single stage, 1-1/2 stage (outbound propellant tanks expended), and common stage configurations are all candidates for the POTV mission. Additionally, for those cases where economic cargo transportation is possible, significant advantages accrue to the POTV by having its return propellants delivered by the more economic COTV and stored in GEO. TECHNOLOGY BASE The following POTV technology definitions and selections have been developed as compatible with an assumed 1980 + technology base, (excerpted from the Boeing FSTSA Study.) Structures: o Graphite-plastic matrix composites are assumed for unpressurized main structures. o Aluminum is assumed for main propellant tanks with integral stiffening as required.
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