Orbit determination for a radar mapping satellite of Venus

The capabilities of the ground-based and spaceborne measurement data processing system which has been developed by the Keldysh Institute of Applied Mathematics of the USSR Academy of Sciences are described. The system has been used successfully for the radar mapping of Venus from the Soviet Venera 15 and 16 spacecraft. The data processing system is based on a mathematical model of the orbital motion of a Venusian artificial satellite. In this model the satellite motion in the gravitational field of Venus is affected by perturbations due to the oblateness of the field, the gravity of the sun and planets, and the light pressure on the satellite surface. These perturbations give rise to the satellite's orbit evolution. (L.K.S.)