“By preventing dangerous asteroid strikes, we can save millions of people, or even our entire species. And, as human beings, we can take responsibility for preserving this amazing evolutionary experiment of which we and all life on Earth are a part.” -Rusty Schweickart
Asteroid strikes are among the most destructive natural disasters to ever impact planet Earth. While an extinction-level event, like the one that wiped out the dinosaurs some 65 million years ago, are exceedingly rare, we face city-killer impacts somewhere on Earth’s surface every few hundred years.
Meteor (Barringer) crater, in the Arizona desert, is over 1.1 km (0.7 mi) in diameter, and represents only a 3-10 MegaTon release of energy. A 300-400 meter asteroid strike would release 10-100 times the energy. Image credit: USGS/D. Roddy.
If one such event happened over an actual city, the chain reaction of destructive events would begin with a fireball, followed by thermal radiation, causing millions of people to die. Buildings would be leveled for an even greater distance, while inevitable destruction would continue far beyond that. But the greatest number of people would suffer from burns, even from scores or hundreds of miles away.
The consequences of a 500 meter-sized asteroid striking Chicago. Image credit: InsuranceQuotes with NASA data, via http://www.insurancequotes.com/home/near-earth-close-calls-cosmos.