Washington (CNN)Russia plans to modify some of its intercontinental ballistic missiles to destroy asteroids before they hit Earth, according to a top Russian rocket researcher. Sabit Saitgarayev of Russia's Makeyev Rocket Design Bureau revealed the effort during an interview last week with the government-owned TASS news agency. The United States is also working on ways to prevent asteroids from hitting Earth, but is taking a very different approach. Instead of blowing up the space rocks, NASA plans to shove them away from the planet. It is the latest frontier in efforts by both countries to tackle a threat to the planet that dates at least from the extinction of the dinosaurs. The Russian...