A scheme for simplified trajectory design in aero-gravity assist using singular orbits

This paper proposes a novel strategy for simplified trajectory design in aero-gravity assist missions. In aero-gravity assists, the extent of deceleration and the periapsis altitude are coupled and dependent to each other, which makes it difficult to obtain desired outgoing trajectory. We insert a one-revolution orbit as a trajectory leg just after the aero-gravity assist so that we can utilize degrees of freedom in design for connecting two trajectory before and after the swing-by. After one-revolution interplanetary cruise, the S/C re-encounters the planet and thus has a chance to go to new destination by a usual gravity assist, or to experience aero-gravity assist again, which allows us various interplanetary missions afterward. This paper describes the difficulty in design of aero-gravity assists, outline of our novel approach and its detailed procedures. A case study for Earth aero-gravity assist design is also shown.