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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. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

With the increased interest and attention to Near Earth Objects, there have been many proposals of possible methods of deviating of those objects potentially posing a threat to Earth. One such conceptual method envisioned sublimating the surface material of an asteroid using solar energy directed by mirrors onboard an orbiting or hovering spacecraft. In this paper, this method is examined in more detail, with an emphasis on feasibility. A comparison is made between the complexities of deploying and operating a single large rigid structure around asteroids, with that of a formation of smaller spacecraft. Configurations are presented for different Near Earth Asteroids (NEA), duration of thrust, and achieved deflections. Both simplistic single flat mirror and more complex parabolic reflector-lens assemblies are examined, comparing the initial spacecraft mass and payload sizing for various formation sizes. Relative periodic formation orbits are found accounting for perturbations due to the Sun and NEA, and for the solar pressure on the mirror payload on the spacecraft. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]