Orbit refinement for «Spectr-R» spacecraft of Radioastron mission by radio range and Doppler measurements

The article presents the first results of state vector refinement for the «Spectr-R» spacecraft of «Radioastron» mission which is a part of earth-space radio interferometer. The state vector contains three spacecraft’s components for position and three components for velocity in Geocentric Celestial Reference System. Kahlman filtering iteration process based on a radio range and Doppler data allows to refine the components during each iteration. The paper demonstrates, that obtained results on orbit refinement improve orbit accuracy provided by Keldysh Institute of Applied Mathematics.