Brigadier General Simon Worden, deputy director of operations for Space Command, says that despite the "giggle factor" the military should track Near Earth Asteroids and be ready to destroy them. While extinction-level events happen once every 80 million years or so, much smaller and more common asteroids could devastate large regions. Worden said that there would be some minor extra costs to add this tracking capability and further costs to keep missiles on standby that could reach an appropriate interception point.--Stephen V Cole