China’s COMPASS satellite navigation system consists of five or more geostationary (GEO) satellites. The roles of GEO satellites are to improve the regional user’s positioning accuracy and provide the continuous Radio Determination Satellite Service. The motion of GEO satellites relative to a ground tracking station is almost fixed, and regular orbit maneuvers are necessary to maintain the satellites’ allocated positions above the equator. These features present difficulties in precise orbit determination (POD). C-band ranging via onboard transponders and the L-band pseudo-ranging technique have been used in the COMPASS system. This paper introduces VLBI tracking, which has been successfully employed in the Chinese lunar exploration programs Chang’E-1 and Chang’E-2, to the POD of GEO satellites. In contrast to ranging, which measures distances between a GEO satellite and an observer, VLBI is an angular measurement technique that constrains the satellite’s position errors perpendicular to the satellite-to-observer direction. As a demonstration, the Chinese VLBI Network organized a tracking and orbit-determination experiment for a GEO navigation satellite lasting 24 h. This paper uses the VLBI delay and delay-rate data, in combination with C-band ranging data, to determine the GEO satellite’s orbit. The accuracies of the VLBI delay and delay rate data are about 3.6 ns and 0.4 ps/s, respectively. Data analysis shows that the VLBI data are able to calibrate systematic errors of the C-band ranging data, and the combination of the two observations improves orbit prediction accuracy with short-arc data, which is important for orbital recovery after maneuvers of GEO satellites. With the implementation of VLBI2010, it is possible for VLBI to be applied in the COMPASS satellite navigation system.

A kinematic statistical method is proposed to determine the position for Chang’E-3 (CE-3) lunar lander. This method uses both ranging and VLBI measurements to the lander for a continuous arc, combing with precise knowledge about the motion of the moon as provided by planetary ephemeris, to estimate the lander’s position on the lunar surface with high accuracy. Accuracy analyses are carried out with simulation data using the software developed at Shanghai Astronomical Observatory in this study to show that measurement errors will dominate the position accuracy. Application of lunar digital elevation model (DEM) as constraints in the lander positioning is also analyzed. Simulations show that combing range/doppler and VLBI data, single epoch positioning accuracy is at several hundred meters level, but with ten minutes data accumulation positioning accuracy is able to be achieved with several meters. Analysis also shows that the information given by DEM can provide constraints in positioning, when DEM data reduce a 3-dimensional positioning problem to 2-dimensional. Considering the Sinus Iridum, CE-3 lander’s planned landing area, has been observed with dedicated details during the CE-1 and CE-2 missions, and its regional DEM model accuracy may be higher than global models, which will certainly support CE-3’s lander positioning.