NASA on Wednesday launched a spacecraft with one simple mission: Smash into an asteroid at 15,000 mph.

The mission, the Double Asteroid Redirection Test, or DART, left Earth to test whether slamming a spacecraft into an asteroid can nudge it into a different trajectory. Results from the test, if successful, will come in handy if NASA and other space agencies ever need to deflect an asteroid to avert a catastrophic impact on the Earth.

Q: When was the launch and what happens next?