9th IAA PLANETARY DEFENSE CONFERENCE 2025

The hypothetical asteroid threat exercise for the 2025 planetary defense conference includes an intriguing trajectory design challenge for possible deflection missions. The long (17 years) time span between the impact threat announcement and the possible impact date allows one to exploit multiple gravity assist (MGA) trajectories involving the inner solar system planets to allow an otherwise impossible low relative velocity rendezvous reconnaissance mission and, additionally, to improve the deflection performance of a kinetic impactor. In this work, we exploit a rapid Lambert-free sequence-independent trajectory finding algorithm [1] able to compute all possible MGA trajectories to the asteroid before the expected impact and select suitable reconnaissance and impact solutions among them. As expected, gravity assists are sine qua non for a feasible rendezvous with optimal phasing near perihelion. Additionally, the most promising solutions are characterized by multiple resonant legs. Interestingly, though, gravity assist impact trajectories (impacting almost tangentially and also near perihelion) appear to be more effective compared to direct ones for the proposed scenario. A rendezvous reconnaissance mission followed by a kinetic impact deflection mission appears to be technologically feasible with carefully designed MGA trajectories and multiple launch and arrival opportunities are available.