Abstract: Tracking and Data Relay Satellite System (TDRSS) is one of the hot spots in aerospace engineering recently. Firstly, the antenna coordinate system of the Tracking and Data Relay Satellite(TDRS) is defined and the tracking laws from the user satellites to the TDRS are derived according to the requirement of the TDRSS. The antenna's azimuth and elevation angles can be derived through the tracking laws when the TDRS is tracking the user satellites. In order to ensure the correspondence between the TDRS and the user satellites, the SA (Single-Access) antennas of the TDRS need to point the user satellites accurately. The antenna pointing control concepts are described, and the on-board autonomous control scheme is designed. The on-board autonomous control scheme is composed of acquisition and autotrack modes. On one hand the acquisition process of the SA antenna is designed, and on the other hand, the antenna step logic of the autotrack mode is properly selected. Finally, the mathematic simulation of the antenna pointing control system designed in this paper is conducted in the case of taking the user satellites in different orbits as tracking objects according to tracking laws derived before, and the SA antenna pointing performance of the TDRS is demonstrated by the analysis of the simulation results.

Key words: TDRS, user satellite, single access antenna, on-board autonomous control, acquisition mode, autotrack