Scientists attended a conference in Orange County, Calif., and pitched ideas for preventing the Earth's next devastating asteroid strike, predicted to occur once every million years. Methods proposed ranged from nuclear blasts in space to lasers.
Scientists think that any of the roughly 700 near-Earth bodies more than a kilometer wide could cause global destruction. Even something about 1/10 of that size could wreak large-scale havoc, they theorize.
The gathered scientists emphasized the importance of detecting such asteroids, saying that could provide years or even decades to decide what to do about it - such as slowing down its arrival by six minutes, which would allow Earth to "dodge" it. Source