Abstract: Orbit determination for GEO objects using two short arcs from space based optical observations plays a key role in the space-based space surveillance systems. The significant information of a short arc was represented by an attributable including two angles and their time derivatives at the mean time. The admissible region was constructed to constrain the distance and the radial velocity between the surveillance satellite and the GEO object. Using the force equilibrium of a truss structure, the admissible region of the first arc was sampled by triangulation. The orbits of these samples were propagated to predict the attribute of the second arc. By comparing the predicted attribute with the actual one, several proper preliminary orbits were determined for orbit improvement. The simulation results show that our method can successfully achieve the least square solution and indicate the excellent convergence behavior.

Key words: Short arc, Truss equilibrium method, Sampling method, Least-square orbit, Orbit determination, Space object, Geosynchronous earth orbit