Abstract: For the predictive guidance with zero effort miss (ZEM) taken as a performance objective for exoatmospheric interception problem,the prediction accuracy of ZEM directly influences the completion of terminal intercept mission.  In this paper, a ZEM forecasting method based on the targetcentered orbit frame is introduced by using the linearized inverse square gravity model.The condition of ZEM occurrence is derived and one method for improving prediction accuracy of ZEM is also put forward,which can distinctly improve the prediction accuracy by choosing the initial orbit angular velocity.Moreover this method is compared with the one based on ECI frame by simulation.The results indicate that the improved one has higher accuracy and certain value to practical application.

Key words: exoatmospheric interception, zero effort miss, ZEM forecasting, relative motion, targetcentered orbit frame