Method of Spacecraft Initial Orbit Determination Base on the Launch Vehicle Apparent Position and Apparent Velocity

To make the best of information source for spacecraft initial orbit determination and to continuously inprove the ground Tracking, Telemetry and Command (TTC) orbit determination means and method, this paper proposes a spacecraft initial orbit determination algorithm based on the launch vehicle apparent velocity. Firstly, the principium of measuring trajectory by use of the launch apparent position and apparent velocity is analyzed. Secondly, using the launch vehicle second node computer word (i.e. apparent velocity) and the initial trajectory of a certain point (initial position vector and velocity vector), the position vector and velocity vector of each second are acquired by means of performing the second-by-second integration of the launch vehicle motion equation, and then converted into the ballistic data to directly determine the spacecraft initial orbit. Finally, simulation result on the real-measure data of a sun-synchronous orbit satellite proves the correctness and reliability of this algorithm.