Space Shuttle application of a GPS navigation system

The application of GPS navigation to the Shuttle system will provide an autonomous navigation capability with continuous real-time state vector updates. This, in turn, will significantly increase mission effectiveness, improve propellant management, reduce postflight data reduction time for earth resource applications, and reduce risk margins in abort and contingency landing situations. In this paper, a brief introduction to the STS and its typical mission profile is followed by a description of the proposed GPS-based navigation system. Attention is given to the peculiar system requirements resulting from the space vehicle environment and affecting redundancy, the satellite visibility constraints, and atmospheric entry effects on RF communication effectiveness and system accuracy. Performance parameters are discussed considered from Orbiter navigation and payload/user perspectives.