Optimization of interplanetary trajectories to near-Earth asteroids using electric propulsion

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. In this sense, employing electric propulsion is convenient, given that it is distinguished by a sensibly lower propellant consumption, if compared with chemical propulsion, with a consequent substantial saving in terms of mission costs. The work specifically focuses on the simulation of missions toward ten of these asteroids, from which it is possible to discriminate two different maneuver strategies, each one with different characteristics. The final goal of this thesis consists in determining the causes that make one more convenient than the other, depending on the asteroid taken into consideration, which means that some hypotheses will be formulated and then properly tested using counterproofs, thus entailing the simulation of missions toward the same asteroids while fictitiously modifying the orbital parameters of the asteroids themselves. In order to optimize the trajectories of the missions, the theory of optimal control will be applied, using indirect methods of resolution of the fundamental equations, which are characterized by a significant numeric precision, with a low number of parameters and limited time of calculation.