Design and optimize scheme of transfer trajectory for near Earth asteroid exploration mission

Designing transfer trajectory for exploration asteroid mission is different from conventional orbit design due to requiring more energy. So it is difficult to realize exploring mission only using impulse direct transfer trajectory. For this problem, taking the 3288 Seleucus asteroid as an example, the transfer trajectory technology of the Earth gravity assist with deep space maneuver is used to design transfer trajectory for exploring near Earth asteroid mission. In order to design Earth gravity assist transfer trajectory, spacecraft is propagated to aphelion of elliptical orbits with 2-years period and then spacecraft return to Earth for swing-by by means of putting on deep space maneuver. To reduce the total velocity increments further, analytic first derivatives are derived using the variation and primer vector theory, then the complicated multi-dimensions nonlinear optimal problem is transformed into parameter optimal problem. The transfer trajectory profiles for exploring Seleucus asteroid is optimized using qusi-Newton algorithm. The numerical calculation indicates that the design method of the Earth gravity assist with deep space maneuver can effectively reduce total velocity increments requirements, especially launch energy requirements.