Trajectory Optimization of a Bimodal Nuclear Powered Spacecraft to Mars

摘要

Minimum flight times for a bimodal, nuclear powered spacecraft are sought. Adirect trajectory from Earth to Mars is utilized. Earth escape and Mars braking is accomplished with a high thrust, nuclear thermal propulsion unit, while the interplanetary transit is achieved by a low thrust, electric propulsion unit whose thrusting direction may be varied. An existing method that maximizes circular orbit transfer is adapted to the problem by simplifying the escape and braking conditions and requiring the final orbit to be that of Mars thus obtaining minimum flight times. Low thrust direction history, phi(t), excess high thrust fuel division between the escape and braking burns, and optimal escape injection angles are found that determine the minimum flight time. Finally, the size of the low thrust propulsion is also varied to find the minimum time of flight. Keywords: Celestial mechanics, Computer programs, Theses. (JHD)