Via Christianity Today:
Systematic search programs have dramatically increased the rate of discovery of NEOs and lowered the risk of impact. As of 1990, only 134 NEOs had been discovered. Today, more than 8,800 have been identified. No large asteroid yet discovered is likely to impact Earth within the next 200 years, though the asteroid Apophis will pass within the orbits of communication satellites on April 13, 2029.
An object’s path would need to be altered only slightly to transform a catastrophe into a harmless fly-by. Yeomans offers several feasible suggestions for such a mission, but success would depend on early detection and thorough analysis. The worst-case scenario would be a large long-period comet heading toward Earth. Long-period comets are practically invisible until they pass Jupiter, at which point we would have only nine months before a potential impact.
A greater problem could be the political question of who is responsible for coordinating a deflection mission. On October 6, 2008, astronomers at the Minor Planet Center, JPL, and NASA detected a small asteroid that would explode over northern Sudan in less than 12 hours. They suggested that US officials contact the Sudanese government to prevent panic and request permission to collect meteor fragments. Because of a lack of formal relations between the two countries, however, no one in Sudan could be contacted in time.
Policy implications because of the need for transnational collaboration.