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  • Design and dynamic testing of an ultrahigh accuracy satellite stabilization and control system for the orbiting astronomical observatory

    Paper ID



    • D. A. Imgram
    • R. R. Ziemer
    • E. Stern


    Grumman Aircraft Engineering Corporation






    The paper describes in detail the configuration and operation of the stabilization and control system for the Orbiting Astronomical Observatory ( OAO ) now being built by NASA. The accuracy requirements in attitude control and some of the reasons for these requirements are discussed. Problems encountered in developing the necessary components and the methods for proving the performance capabilities of the system through dynamic testing are described. The basic facility for performing the dynamic tests is a platform mounted in a low-friction, three-de- gree-of-freedem suspension. For the OAO, a spherical air bearing will be employed to serve as the low friction suspension. The problems encountered in the design in balancing an air bearing, capable of supporting about 7,000 lb at friction levels below 100 dyne/cm are discussed and an automatic technique to achieve rapid, high-precision balancing described. The technique of simulating the magnetic environment of the satellite in orbit, including the secular variation in field intensity and dire rection, is described, and the introduction of time-varying disturbance torques into the system by means of magnetic torquing of the air bearings are discussed. In order to demonstrate proper system performance during all phases of operation, the celestial references utilized by the sensors on the spacecraft must be simulated in the Laboratory. Design and construction of the solar simulator and star source collimators employed in the dynamic test facilities are presented.