331E-350-Asteroid Defense

In 2013 a 56 foot diameter space rock exploded over Chelyabinsk, Russia releasing the energy of 450 kt of TNT and filled local hospitals with some of the 1,500 people who were injured. Fortunately no one died. In 1908 a 200 ft diameter meteor exploded over a largely unpopulated region at Tunguska, Siberia knocking down trees over a 750 square mile area. If it had hit over a populated area it could have caused a million casualties. The approximately 250 people in the USA that NASA has working on asteroid detection and ways of mitigating the effects of an asteroid impact have plenty to do. We still have to locate and track about a hundred very large asteroids which could produce global climate change. Further, there are approximately 14,500 undiscovered slightly smaller ones which could cause a hurricane sized footprint damage areas to land areas on our planet. Fortunately it is extremely unlikely that any but one of the smallest space rocks will hit the Earth in the next 100 years.