A trajectory optimization strategy for a multiple rendezvous mission with Trojan asteroids

In the overall context of a solar sail mission in the vicinity of the Trojan asteroids swarm around the L4 Lagrange point, the purpose of this work is to find an optimal sequence of asteroids rendezvous that accommodates given mission constraints. A currently considered strategy to solve this problem will be presented and design choices will be outlined. A subset of the Trojan asteroids database is first extracted based on orbital elements considerations and a tree containing all the potential sequences is generated. A first set of pruning techniques is applied to the tree in order to quickly reduce the search space by several orders of magnitude. A global optimization method is then used: it combines a branch-and-bound approach and an evolutionary algorithm to find good sequence order, departure date, transfer and coasting durations. In order to enable a fast computation of potential transfer costs, the dynamics are linearized around L4 and the ΔVs are computed analytically. Preliminary results show a drastic reduction of the search space along with a reasonable accuracy on the cost prediction. This method has been used to analyze a tour scenario starting from 588 Achilles and including three rendezvous; the final result provides a list of sequences of potential interest.