Asteroid impacts and modern civilization: Can we prevent a catastrophe?

We are now approaching the level of technical expertise necessary to deflect a near-Earth asteroid (NEA) capable of destroying a large urban area, if not a small country. The current level of activity in the field, including search programs, physical characterization, and international initiatives to assess mitigation strategies, is unprecedented. However, we have only just started to explore the relevant properties of the small end of the NEA population (diameter < 300 m), of which the next major impactor is most likely to be a member. The Chelyabinsk event has reminded us that objects as small as 20 m, about which we know very little, impact frequently and are a serious threat to life and property. Political awareness and international response efforts are still at a very primitive stage. For a global guarantee of protection, advances in scientific and technical competence must be matched by improvements in international coordination, and preparedness at the political level