DavidReneke has a link to how FEMA and NASA are making plans to respond to an asteroid aimed at earth.
NASA and the Federal Emergency Management Agency (FEMA) came together Oct. 25 to plan a response to such a hypothetical event. In a “tabletop exercise,” a kind of ongoing simulation, the two agencies tested how they would work together to evaluate such a threat, prevent panic and protect as many people as possible from the deadly collision.
“It’s not a matter of if, but when, we will deal with such a situation,” Thomas Zurbuchen, NASA’s Science Mission Directorate’s new associate administrator, said in a statement. “But unlike any other time in our history, we now have the ability to respond to an impact threat through continued observations, predictions, response planning and mitigation.”
these "war game" type scenerios go on all the time, from city wide "disaster drills" to the "Dark Winter" exercize that posited a smallpox biowarfare attack.
ther article here discusses a five day warning for a near earth object hit.This would be for the smaller asteroids that would mainly have local damage/casualties. These hits are a lot more common than the big ones that would cause mass extinction.
Bruce Willis call your office.
We haven’t always had any notice for approaching asteroids. Look at the Chelyabinsk meteor from 2013. It was a 10,000 ton meteor that exploded over the Chelyabinsk Oblast, injuring 1500 people and damaging an estimated 3,000 building in 6 cities. If it had been a little bigger, and reached the surface of the Earth, the damage would have been widespread. 5 days notice would likely have saved a lot of lives.