Trajectory optimized design based on bidirectional correction for escape orbit in asteroid defense evaluation mission

Asteroid defense and evaluation mission will be carried out by our country in the near future, the probe for observation and reconnaissance along with the impactor for kinetic energy impact would be launched into orbit by “one rocket, two spacecrafts” approach, then two spacecrafts separate and enter into different Earth parking orbits for orbital transfer independently in subsequent tasks. This article conducts research on the key processes of probe’s orbit design: one is the transfer in the large elliptical Earth parking orbit for selecting a suitable Earth escape window; and the other is the Venus gravity assist flyby after escaping from Earth for reducing the propellant consumption and rendezvousing with target asteroid within a specified time. Firstly, the “global-local” optimization method is adopted to design the initial deep space transfer orbit; secondly, taking the escape orbit coordinates within robust convergence as the initial value, the optimization strategies of differential correction and bidirectional iteration are adopted to design the high-fidelity large elliptical Earth orbit and interplanetary transfer orbit; finally, the feasibility of carrying extra separated payloads is evaluated considering the overall mass and propellant budget constraints, and the available margin of carrying capacity has increased from 15 to 33.7 kg according to the optimized design results.