Precise relative orbit estimation of insat missions

The increase in the use of geostationary satellite services calls for the number of geostationary satellites to be placed close to each other in the orbit leading to the colocation of satellites. Present trend in space communication development calls for keeping a number of clustered satellites in a specified formation to synthesize a large telecommunications system. To operate these satellites without the risk of collision or any other undesired mutual interference, the Inter Satellite Distance (ISD) between these satellites should be maintained within certain limits. Hence it is necessary to explore the feasibility of relative orbit determination as accurately as possible. This paper presents the method of precise relative orbit estimation by means of ground based tracking applicable to Indian Space Research Organisation ' s (ISRO ' s) co-located INSAT missions using weighted least squares technique. Mathematical modeling of relative orbit determination along with sample sets of results using INSAT co-located satellite ' s real data and its comparison with the ISRO ' s regular operational orbit determination for individual satellites is presented.