Low-thrust trajectory design for a low-cost multiple asteroid rendezvous and sample return mission

Sample return missions to multiple near-Earth asteroids are investigated assuming solar electric propulsion as propulsive means. The aim of the mission is to collect the soil samples from multiple asteroids and to return them to the Earth. The objective of the trajectory design is not only to maximize the number of the target asteroids and the payload mass of the spacecraft, but also to make the flight time up to the Earth return as short as possible for quick science return. Two options are studied for the orbital sequence. The first scenario introduces Earth gravity-assist after each asteroid rendezvous in order to return the reentry capsule as fast as possible as well as to reflect the result of the sample analysis for the following mission scenario. The other trajectory option is designed without Earth gravity assists.