NASA launching craft to hit asteroid

Want to see a spacecraft smash into an asteroid... for science?

It sounds a lot like a movie plot, but it's actually a NASA experiment that could have big implications for planetary defense. If the spacecraft — named Dart — can knock a small, harmless asteroid into a changed orbit, we might have a fighting chance if a killer asteroid ever comes Earth's way.

According to the schedule on NASA's Live webpage, live coverage starts at 6 p.m. Eastern. For the moment of the crash, NASA is aiming for 7:14 p.m. Eastern.