Asteroid impacts: How to avert Armageddon

http://www.economist.com/blogs/babbage/2013/02/asteroid-impacts     / threats posed space rocks meteor meteorite asteroids hit Earth risk impact crater shock wave  passed overhead blew out windows injured hundreds of people 2012 DA14 zipping past Earth inside orbit some man-made satellites astronomers strikes NASA America's space agency watching the sky rock orbits bring them close to Earth near-Earth object NEO track tracking tracked down around 90% of the very biggest NEOs planet killers a kilometre or more across wiped out dinosaurs 7-10km heavyweights are smaller less dangerous damage hit town city hard harder to spot NEO-detection detection Japanese Space Agency universities ask for more money to expand their search researchers, meanwhile pondering what to do if an asteroid is detected that is indeed on a collision course with Earth blast dangerous asteroid apart using nuclear weapons doomsday scenario fracture large asteroid into several smaller ones 1996 Comprehensive Test Ban Treaty bans nuclear explosions in space The European Space Agency  mission called Don Quijote large heavy spacecraft to ram an asteroid out of the way send sending a rocket engine to an asteroid could work if the asteroid in question was relatively small and was detected with plenty of time to spare proposal paint one side of an asteroid in light or dark colours, tweaking its trajectory via a neat bit of physics called the Yarkovsky effect that describes the way in which sunlight gives celestial bodies a gentle push gravity tractor in orbit around an asteroid, and relying on its gravity to tug the rock gently out of the way /