Chinese researchers believe they may have found the most effective way to destroy or deflect a large, Earth-threatening asteroid – by burying a nuclear bomb beneath its surface and exploding it. The idea is to first slam a metal penetrator into the asteroid, digging a deep hole. A second spacecraft would then drop a nuclear bomb into the hole and blow it up, according to a team led by researchers at the China Academy of Launch Vehicle Technology in Beijing. In simulations, a 3-megaton explosion...