Locating the Ground Antennas for the Orbit Determination System of RODS

In this paper, the necessity of orbit determination is explained at first. Then, the one-way ground-based tracking system of launcher team is introduced as the only current domestic solution of IRI, whose success has not been confirmed by ISA. Hence, the orbit determination system of RODS is proposed, which is a GNSS-like positioning system with 4 time-synchronized ground antennas. Here, the location of these beacons within the territory of IRI is specified. For this purpose, 2 criteria is considered. First, their common horizon with minimum elevation angle of 10 degree should cover LEO satellites above the altitude of 500 km. This criterion leads to square admissible area with side length of 1000 km. Second, the formation of the ground antennas should provide an optimum configuration from the viewpoint of PDOP. Accordingly, the solution to this optimization problem is carried out by GSA inside the admissible area. The optimal result consists of 3 outer beacons on the boundary of admissible area and a central one, which are associated with the image of a star. So, the best configuration is the largest regular star with 3 equal arms and internal angles of 120 degree that is enclosed by admissible area. Consequently, the airports of Kerman, Chabahar, Mashhad and Khark are proposed for the location of the 4 ground antennas of RODS.