A multi-criteria assessment of deflection methods for dangerous NEOs

Over the last few years, the possible scenario of an asteroid threatening to impact the Earth has stimulated an intense debate among the scientific community about possible deviation methods. In this paper we present a comparative assessment of some of the more feasible mitigation schemes reviewed in the literature (i.e. solar collector, nuclear blast, kinetic impactor, low-thrust propulsion and mass driver). For each strategy, a multi-criteria optimization method has been used to construct a set of Pareto optimal solutions, minimizing both the mass of the spacecraft and the warning time, while simultaneously maximizing the deviation. A dominance criterion has then been defined and used to compare all the Pareto sets. The achievable deviation at the MOID, either for a low-thrust or for an impulsive maneuver, has been computed through a set of analytical formulas. The variation in the orbit of the NEO has been estimated through a deviation action model that takes into account the wet mass of the spacecraft on the Earth. Finally the technology readiness level of each strategy has been used to recompute a more realistic value for the required warning time.