In this thesis a strategy of optimization of missions towards Near-Earth asteroids using electric propulsion will be analiyzed. Near-Earth asteroids, or NEA, are a class of asteroids characterized by being very close to the Earth, and this aspect makes them extremely interesting, firstly in order to monitor their positions and predict eventual potential impacts with Earth and, secondly, since it is meaningful to study and determine their physical characteristics so that it will be possible to deduce much information about the origin of life on our planet, also taking into account the rate at which new ones are discovered, thanks to sky observations.