The DART mission slammed into an asteroid in a test of technology that could be used to divert a killer asteroid.

One NASA presentation said "humanity one, asteroid zero".

Deep Impact

The final moments went quickly, with the asteroid appearing larger and larger on NASA TV until the moment of impact, when mission control erupted in applause.

One person on the NASA screen said "Oh my gosh".

DART Board

Didymos is a double asteroid system. If a killer asteroid arrives, the mission will be able to gently push it off the path.

DART is an attempt to demonstrate how humans could defend themselves against the type of impact that is believed to have killed the dinosaurs.

Another person said that it was beautiful to watch.

Planetary defense experts complain that satellites make it hard to spot killer asteroids.