文中的软着陆过程从一条环月停泊轨道开始。一旦选定着陆点 ,则通过ΔV变轨转入一条椭圆轨道。当到达近月点时 ,着陆制动发动机点火 ,开始动力下降阶段。参考运载火箭制导过程的分析方法 ,假设月球为一均匀引力场 ,以燃耗最优性为出发点 ,提出了一种用于软着陆动力下降过程的显式制导律。其显式表达式是剩余时间的函数。它不必进行迭代计算 ,是一种易于实现的次优闭环制导方法 The text of the soft landing process from a mooring orbit began. Once the landing site is selected, the orbit changes into an elliptical orbit by ΔV. When it reaches the nearest point, the landing brake engine ignition, start the power down phase. With reference to the analysis method of guided rocket guidance process, assuming that the lunar is a uniform gravitational field, an explicit guidance law for the descent of soft landing force is proposed based on the optimal fuel economy. Its explicit expression is a function of the remaining time. It does not have to be iteratively calculated and is an easy-to-implement suboptimal closed loop guidance method