An anonymous reader submitted a link to an International Herald Tribune story about NASA's answer to the movie 'Armageddon'. Specifically, they've outlined a plan to deflect a planet-killer asteroid
. "In 1998, Congress gave NASA's Spaceguard Survey program a mandate of 'discovering, tracking, cataloging and characterizing' 90 percent of the near-Earth objects larger than one kilometer (3,200 feet) wide by 2008. An object that size would probably destroy civilization. The consensus at the conference was that the initial survey is doing fairly well although it will probably not quite meet the 2008 goal."
With this tracking system in place, scientists are hopeful an intervention could be staged before any grim choices have to be made. Assuming they have the money and manpower needed for the effort, NASA has actually outlined a pair of procedures that dove-tail with each other: "First we would deflect the asteroid with kinetic impact from a missile (that is, running into it); then we would use the slight pull of a 'gravity tractor' -- a satellite that would hover near the asteroid -- to fine-tune its new trajectory to our liking. (In the case of an extremely large object, probably one in 100, the missile might have to contain a nuclear warhead.) To be effective, however, such missions would have to be launched 15 or even 30 years before a calculated impact."