Basic targeting strategies for rendezvous and flyby missions to the near-Earth asteroids

Missions to asteroids and comets are becoming increasingly feasible both from a technical and a nancial point of view. In particular, those directed towards the Near-Earth Asteroids have proven suitable for a low-cost approach, thus attracting the major space agencies as well as private companies. The choice of a suitable target involves both scientic relevance and mission design considerations, being often a dicult task to accomplish due to the limited energy budget at disposal. The aim of this paper is to provide an approach to basic trajectory design which allows to account for both aspects of the problem, taking into account scientic and technical information. A global characterization of the Near-Earth Asteroids population carried out on the basis of their dynamics, physical properties and ight dynamics considerations, allows to identify a group of candidates which satisfy both, the scientic and engineering requirements. The feasibility of rendezvous and yby missions towards them is then discussed and the possibility of repeated encounters with the same object is investigated, as an intermediate scenario. Within this framework, the capability of present and near future launch and propulsion systems for interplanetary missions is also addressed.