Optimal trajectory design for global exploration of an asteroid via bi-impulsive transfers

Abstract

The trajectory for a global exploration of an asteroid is designed to make a comprehensive investigation of different areas. The areas to be visited are considered as target points scattered on the asteroid's surface and all the target points are supposed to be visited by the spacecraft propelled by impulsive thrusts. The trajectory of the spacecraft is optimised for fuel saving in two parts: the transfer orbit optimisation and the exploration sequence optimisation. Firstly, transfer orbits between any two target points via two impulses are optimised for fuel saving by solving a nonlinear programming problem. The solution of the Lambert problem in the gravitational field of a point mass is used as initial guesses in the optimisation. Then, with all the optimal transfer orbits determined, the exploration sequence is processed as a travelling salesman problem (TSP). Branch and bound method and greedy algorithm for solving this problem are compared. Finally, the trajectory for a global exploration of the asteroid 433 Eros is designed for a demonstration purpose.