REUSABLE ORBITAL TRANSFER VEHICLE APPLICATIONS OF AN INTEGRATED SOLARUPPER STAGE

There has been resurgent interest in the development of a reusable orb it transfer vehicle, based in low-Earth-orbit, for satellite placement , repositioning, recovery and control. An integrated solar upper-stage system is examined for several near-Earth applications, including low -Earth to geosynchronous to low-Earth orbit ferrying, An integrated so lar upper stage (a solar thermal power and propulsion system) permits rapid access to high orbits because of its moderate thrust levels (ten s to hundreds of pounds) at specific impulses approaching 900 s, inter mediate between high-performance chemical propulsion and electrical pr opulsion systems. An integrated solar upper-stage reusable orbit trans fer vehicle can be used in two novel modes: 1) Drag return, in which l arge, rigid solar concentrators provide an aeroassist capability lower ing total delta-V requirements; and 2) a hybridized integrated solar u pper stage, coupled with and providing power to a xenon ion thruster, allowing more efficient maneuvers in nontime critical applications.