Asteroid deflection. Computer artwork of rocket explosives being used to deflect an asteroid from its impact course with Earth. The explosions would be intended to nudge the asteroid off course, and not merely cause the asteroid to disintegrate. The impact of several large asteroid fragments hitting Earth would be nearly as catastrophic as the whole asteroid hitting Earth. An asteroid is more likely to break up if it is made up of light rocks and ices. If it is a heavier iron-containing asteroid, then controlled explosions near the surface may be able to divert it from its course without the risk of it breaking it up into fragments.