Optimized low-thrust mission to the Atira asteroids

Atira asteroids are recently-discovered celestial bodies characterized by orbits lying completely inside the Earth’s. The study of these objects is difficult due to the limitations of ground-based observations: objects can only be detected when the Sun is not in the field of view of the telescope. However, many asteroids are expected to exist in the inner region of the Solar System, many of which could pose a significant threat to our planet. In this paper, a mission to improve knowledge of the known Atira asteroids in terms of ephemerides and composition and to observe inner-Earth asteroids is presented. The mission is realized using electric propulsion, which in recent years has proven to be a viable option for interplanetary flight. The trajectory is optimized in such a way as to visit the maximum possible number of asteroids of the Atira group with the minimum propellant consumption; the mission ends with a transfer to an orbit with perigee equal to Venus’s orbit radius, to maximize the observations of asteroids in the inner part of the Solar System.