Abstract: It is very necessary to execute orbit correction for ultra-low-orbit vehicle, whichisbadlyinfluenced by near-earth environment.The orbital motion equation which considered the non-spherical perturbation and atmospheric perturbation was linearized. Then, an impulse correction method was introduced and used to keep a near-earth vehicle flying along the standard orbit. Furthermore, a method to eliminate errors caused by linearizationwasalso studied.The feasibility of the correction method was validated by simulation. For a 120km-altitude vehicle, flying one hour, the optimal correction times is 6, the required △v is 63.7971m/s.

Key words: Orbitcorrection, Linearizedmotionequation, Perturbation, Impulsethrust, Ultralowearthorbit, Spacecraft