Abstract: The theoretical research and engineering practice of Mars exploration need a systematic series of time—space transformation coordinate systems tO describe the orbital motion of Mars probes.During the Mars exploration missions,the relative motion information of the probe around the Mars should be presented.However,the Earth—based ground tracking and control can only provide the relative motion information of the probe around the Earth.In order to solve this problem,definitions of several Mars—centered coordinate systems were given,and computation methods of the transformation matrices between different coordinate systems were introduced.In the end,the numerical simulation of the Mars probe's orbit dynamics based on the time-space bench put forward in this paper was carried out.The results were compared with those obtained from based on STK.The comparison between the results demonstrates the validity of the time space transformation system.

Key words: Orbital motion, Time-space, transformation, Coordina te transformation Numerical simulation Mars exploration