The second qualification flight of Ariane 5 was launched from the European Space Port in French Guiana on October 30, 1997. It carried on board a small technology demonstration satellite dubbed TeamSat into which five experiments, proposed by various universities and research institutions, were integrated. Among them, the Autonomous Vision System, AVS, a fully autonomous star tracker and vision system. This paper gives a short overview of the TeamSat satellite design, implementation and mission objectives. The AVS is described in more details. The main science objectives of the AVS were to verify, in space, multiple autonomous processes intended for spacecraft applications such as autonomous star identification, attitude determination and identification and tracking of non-stellar objects, imaging and real-time compression of image and science data for further ground analysis. AVS successfully determined the attitude and attitude dynamics of TeamSat.