Electrically-Controlled Demand-Thrust Rockets for Satellite Guidance

Satellites which can be positioned precisely in space will be required for the space research programs of the near future. The information obtainable with such vehicles will be of immediate importance to both military and basic scientific research programs. Typical applications include meteorological observations, communications, atmospheric research and, ultimately, soft-landing vehicles for manned space travel. To accomplish accurate control of orbit and/or attitude with rocket motors requires extremely precise regulation of thrusts, generally in the range between 0 to 1 or 0 to 10 pounds. It must be possible to turn these control forces on and off in a few milliseconds repeatedly or intermittently over periods of from several months to perhaps several years. For use in such applications, rocket units have been investigated which employ the combination of storable-liquid propellants and demand-thrust injectors capable of complete remote control. An experimental model of a 0- to 10-pound thrust engine has been successfully demonstrated. Three types of electrically actuated control systems are being investigated. These systems employ direct solenoid control, a magnetic ram hydraulic booster, and a micropump with a hydraulic servomechanism. Guidance signals of 50 microamps are used to regulate power to the engine controls.