CEI-based Scheme of Orbit Determination of a Course under Remote Guidance Leading to Spacecraft Rendezvous and Docking

Rendezvous and docking between Shenzhou spaceship and target spacecraft are the goals in the next phase of Chinese space exploration.Connected-element interferometry(CEI)is a method of passively tracking directions and has the advantages of short baselines, flexible station-network distribution,and nearly real-time processing.It allows real-time precision orbit determination for spacecraft rendezvous and docking.We discuss the CEI-based orbit determination of a course under remote guidance leading to spacecraft rendezvous and docking.Our simulation results indicate that the precisions in relative positions between two spacecrafts can be within 100 m and in those relative velocities can be within about one centimeter per second if observational data from a station with long visible arcs (appearing to the spacecrafts)are used.We further use the Extended Kalman Filter to determine real-time(absolute-position)orbits. We find that the method of fixing integer ambiguity after the filtering is stable so that it sets the relative position precision to be 10 m,and sets the relative velocity precision to be within about one centimeter per second.The precisions meet the requirement for a course under remote guidance.