Owing to a 2008 law passed by Congress, the White House Office of Science and Technology Policy has until 15 October to decide which agency will be responsible for protecting the planet from an asteroid strike. Members of the task force say NASA expects to be given part or all of that responsibility.
The U.S. currently spends about $5.5 million per year to track NEO's and less than a million on researching ways to counter them, but is falling far short of asteroid-detection goals. Some might say that's already too much, given the more terrestrial problems the U.S. faces. On the other hand, the United States spends more than $1 billion -- the amount NASA says it needs to meet its goal of detecting all potentially dangerous objects by 2020 -- on far less lofty goals than saving humanity from the fate of the dinosaurs. Even an asteroid just one kilometer in diameter would be enough to cause worldwide crop failures and a shift in the earth's climate. One just a few meters wide could wipe out a major city.
Read the entire article: http://blog.foreignpolicy.com/posts/2010/09/13/why_is_it_americas_job_to_save_the_world_from_asteroids