Integrated Hardware Investigations of Precision Spacecraft Rendezvous Using the Global Positioning System

A closed-loop spacecraft rendezvous simulation facility was constructed and cone gured to evaluate a newly developedrelativenavigationalgorithmthatprocessestheobservablesoftheglobalpositioningsystem.Theprimary objective of this effort is to establish the performance of the integrated guidance and navigation architecture for autonomous rendezvous in low Earth orbit. A fundamental component of the relative navigation system is a real-time recursive extended Kalman e lter. To achieve very precise relative navigation, the e lter processes doubledifferenced carrier-phase measurements. Based on the e lter state, all of the maneuvers are computed onboard by solving the Lambert targeting problem. The closed-loop simulation investigations show that 3.5 cm or less relative positioning accuracy and 1.0 mm/srelativevelocity estimation accuracy areachievablein theabsenceof multipath. Withthesehighlyaccuraterelativenavigationresults,coordinatedandautonomousrendezvousmaneuversbecome possible.