NASA is about to crash a new spacecraft into an asteroid - on purpose. 

The agency's Double Asteroid Redirection Test mission will travel millions of kilometres out into the solar system, to see whether it can knock the asteroid off-course. 

It's all part of a NASA plan to test a method of planetary defence against near-Earth objects. 

Space commentator Matthew Pavletich told Mike Hosking it's less dramatic than it sounds. 

“We’ll be flying at six kilometres a second and we’ll slam into this thing.” 

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