Abstract: To study the initial error propagation of elliptical orbit,a new method was developed based on the state transition matrix of T-H equation. Firstly, the true state and predict state of one space object can be considered as two objects: a real one and a virtual one.Considering predict error as relative motion between these two objects,the relative motion theory was used to study the characteristic of error propagation. Secondly, the state transition matrix of T-H equation was introduced to analyze the propagation of initial error, with which the trend of error propagation in each direction was obtained.Finally, a simulation case was designed to validate the correctness of the new method,and the Monte-Carlo method and the new method were used to calculate error propagation of typical elliptical orbit.The results were compared with the HPOP′s results. Most of the relative error is less than 2%, and is consistent with the trend of the theoretical analysis results.

Key words: Ellipticalorbit, Errorpropagation, Relativemotion, T-Hequation, Statetransitionmatrix, Satellite