Add to ORKGAbstract: In this paper we show that there are four types of optimal solutions for the transfer (time of the flight is not fixed) between close near-circular coplanar orbits. One solution is implemented using a fixed orientation of the thrust vector by transversal in the orbital coordinate frame, the other at a fixed orientation of the thrust in the inertial coordinate frame. At the remaining solutions thrust orientation is changing during the execution of maneuver. The domains of existence of all types of solutions are determined. The algorithms for determination the parameters of these maneuvers were developed. Algorithms were used to calculate the parameters of the transition maneuver from launch orbit to a working sun-synchron...