Determination of the Spacecraft Granat Orbital Motion by Processing Non-Interrogative Measurements of Its Radial Velocity

The paper presents basic characteristics of measuring facilities of the long-distance space communication complex Kobalt in the ground tracking station Medvezhji Ozera for non-interrogative mode of measuring spacecraft radial velocity. The measurements are carried out during transmission of scientific information to the ground by using a transmitter which is not intended for orbit determination. The technique and results of processing such measurements of the spacecraft Granat radial velocity obtained by that complex are described. Processing is carried out in two stages. At first, some functions are found that approximate measurement data collected during individual measure-ment sessions, each session having length about 2 hours. Then the least squares functional are constructed on the base of these functions and sufficiently detailed spacecraft motion equations. Minimization of this functional gives an approximation of a real spacecraft motion. It is shown that acceptable accuracy of this way of motion determining can be obtained by processing at least 12 sessions with duration of every session about 2 hours.