LEASAT Liquid Apogee Motor Subsystem Design

Abstract

This paper describes the bipropellant propulsion subsystem for the LEASAT spacecraft. LEASAT is a Shuttle-launched spacecraft which will provide satellite communications services to the United States Navy. Propulsion is provided by three separate subsystems: a solid perigee motor, a bipropellant subsystem, and a monopropellant reaction control subsystem. The solid perigee motor provides impulse to raise the apogee from the Shuttle parking orbit. The bipropellant subsystem, which utilizes monomethyl hydrazine and nitrogen tetroxide, is designed to provide the impulse required for apogee augmentation and injection into synchronous orbit at apogee. The monopropellant hydrazine reaction control subsystem provides the impulse required for spacecraft spinup, apogee augmentation, attitude and spin speed control, and other required on-orbit maneuvers. The subsystem presented herein is scheduled to be flown in 1982, and represents one of the first configurations designed for Shuttle-optimized spacecraft.