The use of the 'adjacent extremals' method to control the trajectory motion of a space vehicle entering a circular orbit

An algorithm for the suboptimal control of the trajectory of a space vehicle entering a circular orbit is developed on the basis of the adjacent extremals theory, which takes into account the requirement of not only maintaining the control accuracy but also of minimizing fuel consumption. The suboptimal algorithm is shown to assure the precision of the trajectory control in the presence of a wide range of initial disturbances of the phase coordinates. The difference between the suboptimal control obtained using this algorithm and the optimal control was found to be insignificant.