例1 　飞船在近地圆轨道上运行时,由于极稀薄的空气的影响,飞行高度会缓慢降低,需要进行多次轨道维持.轨道维持就是通过控制飞船上的发动机的点火时间和推力,使飞船能保持在同一轨道上稳定运行. 2003年11月份,太阳风暴频发,太阳风暴使“神舟”五号轨道舱运行轨道上的稀薄 Example 1 When the spaceship is operating in a near-surface circular orbit, due to the influence of extremely thin air, the flight altitude will slowly decrease and multiple orbital maintenance will be required. The orbital maintenance is to make the spacecraft control the ignition time and thrust of the engine on the spacecraft. It can keep stable operation on the same track. In November 2003, solar storms occurred frequently. The solar storm made the Shenzhou 5 orbital orbit thin.