Advanced Electric Propulsion for RLV Launched Geosynchronous Spacecraft

ABSTRACT (Maximum 200 words) Solar Electric Propulsion (SEP) when used for station keeping and final orbit insertion has been shown to increase ageostationary satellite's payload when launched by existing expendable launch vehicles. In the case of reusable launchvehicles or expendable launch vehicles where an upper stage is an expensive option, this methodology can be modified byusing the existing on-board apogee chemical system to perform a perigee burn and then letting the electric propulsionsystem complete the transfer to geostationary orbit. The elimination of upper stages using on-board chemical and electricpropulsion systems was thus examined for GEO spacecraft. Launch vehicle step-down from an Atlas IIAR to a Delta 7920(no upper stage) was achieved using expanded on-board chemical tanks, 40 kW payload power for electric propulsion,and a 60 day elliptical to GEO SEP orbit insertion. Optimal combined chemical and electric trajectories were found usingSEPSPOT. While Hall and ion thrusters provided launch vehicle step-down and even more payload for longer insertiontimes, NH3 arcjets had insufficient performance to allow launch vehicle step-down. Degradation levels were only 5% to7% for launch step-down cases using advanced solar arrays. Results were parameratized to allow comparisons for futurereusable launch vehicles. Results showed that for an 8 W/kg initial power/launch mass power density spacecraft, 50% to100% more payload can be launched using this method.14. SUBJECT TERMSElectric propulsion; Orbit insertion: RLV; Geosynchronous satellite17. SECURITY CLASSIFICATIONOF REPORTUnclassified18. SECURITY CLASSIFICATIONOF THIS PAGEUnclassifiedNSN 7540-01-280-550019. SECURITY CLASSIFICATIONOF ABSTRACTUnclassified15. NUMBER OF PAGES1516. PRICE CODEA0320. LIMITATION OF ABSTRACTStandard Form 298 (Rev. 2-89)