Speaker
Description
Near-Earth asteroids that have the potential to impact on our planet essentially on the orbit in which they are discovered, without any substantial perturbation preceding the impact, are often called 'immediate impactors', and deserve special efforts to improve their observational record. Even in cases in which the extension of the observed arc allows to exclude a direct collision, however, there is the possibility of further collisions in the following years, associated to resonant returns. These have, in general, much lower probabilities compared to a direct hit, nevertheless may still be important, especially if the resonant return takes place after a small number of years. We use the analytical theory of close encounters to identify regions in the orbital parameter space where this phenomenon may be more significant.
