Flight Performance of Skylab Attitude and Pointing Control System

In 1967 a paper at the AIAA Guidance, Control and Flight Dynamics Conference in Huntsville, Ala. presented for the first time the prot)osed SKYLAB Attitude and Pointing Control System (APCS) The system requirements, Apollo Telescope Mount (ATM) configuration, control philosophy, and operational modes were presented and the APCS described. The Initial mission and system design requirements changed during the period of time before the SKYLAB was launched. This paper will review the Initial and final APCS requirements and goals and their relationship. The actual flight mission (and Its alterations during the flight) and known achieved APCS performance will then be presented. SKYLAB was a tremendous success in furthering man's scientific knowledge; but perhaps SKYLAB will be remembered more for the anomalies and the efforts undertaken to solve them. On May 14, 1973, the unmanned SKYLAB Orbital Workshop (OWS) was launched from Cape Kennedy. Serious hardware failures began to occur during ascent through the atmosphere and their spectre continued to haunt both the astronauts and their ground based support team. Nor were these the only surprises affecting the design and operation of the APCS. Mission requirements for pointing to various stellar targets and to nadir for earth resources experiments were added after the hardware was designed. The chance appearance of comet Kohoutek during the SKYLAB operational life-time caused NASA to add comet observation to the mission requirements and to adjust the time when the third crew would man the SKYLAB. The development of new procedures and software for the opportunity to observe this visitor to our solar system is described.