EXPLAINER: Why a NASA spacecraft will crash into an asteroid

When the SpaceX Falcon 9 rocket was launched with the Double Asteroid Redirection Test, or DART, spacecraft onboard on November 23, 2021. [AP Photo]

In the first-of-its-kind, save-the-world experiment, NASA is about to clobber small, harmless asteroid millions of miles away.

A spacecraft named Dart will zero in on the asteroid Monday, intent on slamming it head-on at 14,000 mph (22,500 kph). The impact should be just enough to nudge the asteroid into a slightly tighter orbit around its companion space rock - demonstrating that if a killer asteroid ever heads our way, we'd stand a fighting chance of diverting it.