GEOGRAPHY matters. In 1908 a rock the size of a city block hit the Earth’s atmosphere at 15km (9 miles) a second. The explosion flattened an area the size of London. But the land in question was in Siberia, so few people noticed and those who did had little influence. Suppose, though, it had devastated a city in Europe or North America. The history of the 20th century would have been different, as the best scientific and engineering brains were brought to bear on the question of how to stop it happening again.
Well, it has happened again, albeit less spectacularly. By chance, Siberia bore the brunt once more, when a meteor crashed in the Urals on February 15th, injuring more than 1,000 people. It could just as easily have hit Germany or Guangdong. Moreover, on the same day another, larger rock called 2012 DA14 passed within 27,000km of Earth. By astronomical standards, that is a hair’s breadth. It is time to think seriously about stopping such incidents by building a system that can detect space rocks with sufficient warning, and then either blast them or push them out of the way. It would be costly, of course, and would require the development of new technology. But, as luck would have it, there is a tool lying around that has both the money and the nous to do it, and which is currently underemployed and in need of a new mission.