面对日益复杂的空间安全形势，基于轨道机动可达域分析提出了机动航天器接近威胁计算、评估和规避方法。首先，基于可达性判据给出机动能力受限的航天器单脉冲轨道机动可达域求解方法。其次，通过判断在轨航天器自身轨道与来袭航天器机动可达域间的位置关系计算其位于威胁域内的区段，进而得到轨道危险区。再次，基于两航天器进出危险区的时间定义了威胁评价指标，从空间和时间的窗口匹配性角度分别评估在轨航天器受来袭航天器的威胁程度。最后，给出了基于最小化危险区的航天器最优多脉冲接近威胁规避策略，对比了多个脉冲方案结果。仿真结果表明，在轨航天器能够在满足给定约束条件下实现对危险区的机动避让，并以最小燃料消耗回归正常运行轨道。

In the face of the increasingly complex space security situation， this paper proposes an approach based on spacecraft reachable domain for spacecraft maneuvering approach threat calculation， assessment， and avoidance. Firstly， a general method to solve the reachable domain for spacecraft with single limited-magnitude impulse based on the reachable criterion is presented. Secondly， the region in the threat domain of on-orbit spacecraft is calculated by judging the position relationship between its orbit and the reachable domain of incoming maneuvering spacecraft which is the danger area. Thirdly， a threat evaluation index is defined by means of the time two spacecraft enter and exit the danger area. The threat of on-orbit spacecraft is measured from two aspects： position matching and time window matching. Based on minimizing the danger area， an active avoidance strategy of spacecraft with optimum multi-impulses maneuver is given to avoid the danger area. The simulations show that the on-orbit spacecraft can avoid the danger area while satisfying the given constraint conditions， and return to the proper orbit with minimum fuel consumption.