Heliocentric Solar Sail Orbit Transfers with Locally Optimal Control Laws

摘要

A previous (planetocentric) method of assessing the relative importance of orbit elements during solar sail transfers called accessibility and deficit, A~nD, blending has been evolved, allowing rapid generation of heliocentric trajectories by blending locally optimal control laws. An Earth-Mercury trajectory was presented to demonstrate the capability of A~nD blending when attempting to find planet-to-planet transfer trajectories. It was found that the A~nD generated trajectory duration was within 1% of the sequential quadratic programming, SQP, generated trajectory. Thus, A~nD blending can provide a very good rapid assessment of such a mission scenario, or provide an excellent initial guess for further optimization as part of a detailed mission analysis. The A~nD blending method has also been demonstrated for generation of sail trajectories to 200 AU, where it was repeatedly shown that A~nD generated trajectories were very similar in duration to the transfer time found using an evolutionary neurocontroller, which is expected to be near global optimal. Furthermore, the A~nD generated trajectories were consistently more efficient than SQP generated trajectories. A~nD blending has been shown to be able to optimize a solar sail trajectory using a nonideal sail force model. The A~nD blending results clearly demonstrate that a nonideal sail will require a characteristic acceleration of approximately 1.5 mm · s~(-1) to reach 200 AU in 25 years, assuming no optical surface degradation.