Mission to smack a space rock launches
A spacecraft has launched on a mission to test technology that could one day tip a dangerous asteroid off course.
Nasa's Dart mission wants to see how difficult it would be to stop a huge space rock from colliding with Earth
The spacecraft will crash into an object called Dimorphos to see how much its speed and path can be altered.
If a chunk of cosmic debris measuring a few hundred metres across were to collide with our planet, it could unleash continent-wide devastation.
A Falcon 9 rocket carrying the Dart spacecraft blasted off at 06:20 GMT on Wednesday from Vandenberg Space Force Base in California.
It is the first attempt to deflect an asteroid for the purpose of learning how to protect Earth, though this particular asteroid presents no threat.