A 2-D Trajectory Design Algorithm for Multiple Asteroid Flyby Missions

Asteroid mining is one of the most promising private space ventures of the near future. Near-Earth Asteroids (NEA), i.e. those with a perihelion at less than 1.3 AU from the Sun, are among the best candidates for such venture. In preparation of mining expeditions, prospector missions will be carried out well in advance so to assess the accessibility, possible critical issues and potential for revenues of target asteroids. We study the problem of the feasibility of a single spacecraft prospector mission capable of visiting as many asteroids as possible in one shot, focusing on Apollo-class asteroids only. We assume a chemically propelled spacecraft with realistic specific impulse and propellant mass ratio, so to allow for a credible mission design with a reasonable, cost-effective total duration. The domain of trajectories considered is restricted to those lying in the plane of the ecliptic only; therefore, the search for a maximum number of encounters is restricted to those occuoccurringring where the asteroid orbit cross the ecliptic. We adopt a deterministic building blocks approach, dividing the optimization problem in two parts: a local optimization for possible target determination; and a global optimization for the choice of the overall trajectory. In this paper we present the algorithm and the main results and discuss the extension of our method to non-planar, out-of-the-ecliptic encounters.