Ephemeris Generation within the European Space Situational Awareness System

Among the objectives of a future European Space Situational Awareness System (ESSAS), the capacity of maintaining and providing allowed users with a trustable catalogue of orbiting objects and their associated state vectors is of prime importance. The publication of these orbital data can be done by means of different parameterization methods, all of them with advantages and drawbacks. An analysis of the capacity of three of the possible set of parameters for broadcasting orbital information of orbiting objects is addressed in this paper. These methods are: an interpolation scheme as the one proposed in the CCSDS standard [1], the Global Position System (GPS) navigation message and the Two Line Elements (TLE) model.Regarding the provision of covariance matrix information, none of the analysed ephemeris types allows the reporting of such data. A modification of the interpolation scheme is suggested so that the accuracy information can be provided to users.The reported analysis for the Ephemeris generation within the ESSAS is performed by means of the Advanced Space Surveillance System simulator (AS4) developed by DEIMOS Space under several ESA contracts.