On investigation of long-term orbital evolution of geostationary satellites

The averaged motion theory of uncontrolled geostationary satellites (GS) elaborated at the Institute of Theoretical Astronomy was applied to the investigation of their long-term orbital evolution. The declared program ''Resonace'', the main purpose of which is the improvement of the geopotential parameters, is based on this theory. The comparison of orbital elements, obtained from observations and from the theory of orbital evolution, have been shown, that in case of more than 10% from all the known GS a systematical discrepancies arise. This phenomenon has been explained by collisions of GS with space debris. The collisions call additional variations in longitudes of GS equal to 0 degrees.5-1 degrees for a thousand days, what corresponds to the change of the rate of longitude drift approximately 1 cm/sec.