GPS relative navigation for automatic spacecraft rendezvous and capture

NASA, in collaboration with the European Space Agency (ESA), is planning a space experiment involving the space shuttle and two spacecraft in low Earth orbit to demonstrate autonomous rendezvous and capture (AR&C). The results of the preliminary design of a global positioning system (GPS)-based relative navigation filter for AR&C are presented. The domain of operation of the GPS relative navigation filter considered here is from a 2-km separation to 100-m proximity operation. The authors describe the navigation filter algorithm, the truth models employed in the evaluation of filter performance, and the results of the performance evaluation. Relative navigation filter performance results obtained by simulation show a relative position accuracy of about 2 m (1-σ) in the presence of selective availability (SA) errors. In contrast, the performance of the more traditional state vector difference (SVD) method is shown to fluctuate in the 10-20-m range. The results obtained demonstrate that the filter developed provides higher relative navigation accuracy and greater immunity to transients than the SVD approach