极坐标系连续常值推力机动分析

连续常值推力是空间飞行常用的轨道机动方式，在空间交会与星际航行使命中具有重要的应用价值。其中，小推力适合于地球轨道航天器交会机动，而切向或周向推力以及较大的正径向推力可用于脱离地球引力场的逃逸飞行，执行星际交会使命。应用常推力作用下的极坐标系质心运动方程，对机动推力的量值没有限制；在航天器交会应用中，对相对距离也无要求。这种方法可直接获得向径与速度等轨道参数随时间或极角（绕地心的转动角）的变化，便于分析轨道转移与逃逸运动，有助于飞行使命与运动轨迹的设计。特别是，若机动转移的初轨为圆轨道，在推力较小、飞行时间不长的情况下，应用无量纲形式运动方程，可获得具有工程应用价值的近似解。文章给出一些有关的结果与应用案例。

Continuous Constant Thrust Maneuver in Polar Coordinate System

Continuous constant thrust is very important in orbital maneuver and escape flight.Small thrust maneuvers are fit for spacecraft rendezvous,and the tangential(or circumferential)thrust and radial high-thrust can be applied in escaping from the earth's gravitational field.By using the equations of motion in polar coordinate system for constant thrust,there is no limit on the thrust level and no restraints on the relative distance.Orbital radius and velocity can be directly obtained as functions of time or polar angle,which is helpful for design of flight mission and motion trajectory.Especially,when the initial orbit is circular,for small thrust and short flight time,approximate analytic solutions can be derived from non-dimension form of the motion equations.Some interesting results and application cases are given,which are useful for engineering applications.