Thrust continuation of time-optimal orbital transfers with soft terminal conditions

Time-optimal orbital transfers with soft terminal conditions are studied in this work. First, a two-layer thrust continuation method is devised. The unfavorable thrust continuation path is handled by switching between different solution curves. Second, the proposed method is applied to solving time-optimal transfers under two- or three-body dynamics with Cartesian coordinates to verify its effectiveness. The near conservation of the product between the time of flight and the thrust level is observed for general orbital transfers. A linear variation of this quantity with eccentricity is also illustrated when the difference in eccentricity between the initial and terminal orbits is large enough.