Some Considerations in the Design of the Guidance and Control System for Discoverer

The limited number of flight tests to date has indicated that the Discoverer satellite will be a highly reliable and effective system from which the ARPA and the Air Force expect to gain valuable additional knowledge of outer space. The achievement of this high degree of reliability and effectiveness of the satellite means that each of its subsystems must, in fact, be even more reliable and effective. The Discoverer guidance and control system is meeting their specifications because of the simplicity of the over-all design-simplicity for reliability with sufficient sophistication to accomplish its mission effectively. The mission of the guidance system is that of providing adequate attitude, velocity, and time references to guide the satellite into a desired orbit, to control its attitude on orbit, and to provide switching in the proper sequence for certain principal satellite functions. The mission of the control system is simply that of positioning the vehicle in the proper attitude commanded by guidance. The investigations that were made and those which are being continued in the determination of the optimum configuration for the desired performance are described in some detail. The present system, is discussed, which comprises, for guidance, an inertial reference package, a horizon scanner, and a computer for grammar, and for control, both a hydraulic and pneumatic system. In summary, a typical flight of the Discoverer, from separation from the Thor booster until stabilization on orbit, is outlined and the functions of the guidance and control systems are described.