NASA to launch "Armageddon"-style mission to deliberately crash into an asteroid's moon and test "planetary defense"

NASA's upcoming mission might resemble a scene from a sci-fi disaster movie. The agency announced Sunday that it's sending spacecraft above the Earth to crash into an asteroid's moonlet to change the body's trajectory. 

The mission, a Double Asteroid Redirection Test (DART), will be the first agency's use of the kinetic impactor technique, in which a large, high-speed spacecraft is sent into an asteroid's path to change its motion. NASA is set to conduct the mission, what it calls "the first test for planetary defense," on November 24, the day before Thanksgiving, to hit the binary near-Earth asteroid Didymos and its moonlet, Dimorphos. 

The asteroid is roughly 780 meters across — about 2,559 feet, according to NASA. Its moonlet is about 525 feet, which according to NASA, is "more typical of the size of asteroids that could pose the most likely significant threat to Earth."