Abstract: The precision orbit design using planet gravity assist in the high-fidelity model was studied. Orbit design was divided into two steps, preliminary design and iteration in the high-fidelity model. Preliminary design was based on the simplified model. Conic patched method was used to determine the launch window and the impulse induced by gravity assist. Taking the gravity assist as a continuous process in the high-fidelity model, the swing-by hyperbola was transformed into B-plane parameters. The earth-centered departure impulse was taken as design variable and the problem was solved by differential correction. Orbit design for Flora rendezvous in main asteroid belt after Mars gravity assist was presented and the relation of the results between the two models above was compared and analyzed in the illustrative example analysis. The result indicates that the orbit in the high-fidelity model which is based on the simplified model can be reached after few iterations.

Key words: Orbit design, High-fidelity model, Gravity assist, Differential correction, Deep space exploration