Most asteroids orbit in the so-called main belt which lies between the orbits of Mars and Jupiter. Collisions between asteroids in the main belt give rise to fragments, the orbits of which can evolve under the effects of thermally emitted radiation (Yarkovsky effect) and the gravitational influence of planets, primarily Jupiter. Such objects can become Mars- or Earth-crossers, meaning that their orbits bring them within the orbits of these planets. The population of small bodies known as near-Earth objects (NEOs) consists mainly of such objects, together with some nuclei of evolved or extinct comets. NEOs come close enough to the Earth to allow them to be studied in detail with groundbased and orbiting telescopes. Knowledge of the sizes, surface properties and compositions of NEOs is essential for investigations of their origins, their relation to main-belt asteroids, comets and meteorites, the role they have played in the development of the Earth and the threat they pose to civilization as potential impactors on the Earth.
Work carried out by the Department addresses these questions and provides crucial information for the preparation and planning of fly-by and lander missions to asteroids. Activities of Department members include: