First Autonomous Rendezvous Using Relative GPS Navigation by ETS-VII

Engineering Test Satellite-VII (ETS-VII) successfully performed the world's first autonomous rendezvous docking (RVD) flight using relative GPS (RGPS) navigation. ETS-VII is a test satellite designed to perform in-orbit demonstration of autonomous rendezvous docking technology. RGPS navigation is a form of differential GPS (DGPS), and is used as a primary means in the relative approach phase of flight (farther than 500 m from the target satellite). Three methods were used to evaluate the in-orbit performance of the ETS-VII RGPS system during mating flights and rendezvous flights. The accuracy of RGPS navigation was found to be about 10 m in position and 3 cm/s in velocity. This paper describes the evaluation of the in-orbit performance of RGPS during the first autonomous RVD experiment.