DART was bang on target

The asteroid-deflecting DART mission worked with incredible accuracy

AIthough no known asteroid poses a threat to Earth for at least the next century, the database we've built up of near-Earth asteroids is not yet complete for smaller bodies that could still cause devastation on a regional scale.

Several methods have been proposed to protect Earth from asteroids on a collision course, including blowing them up with a nuclear weapon and using a 'gravity tractor', a large spacecraft whose gravity pulls the asteroid so it misses our planet. The strategy identified as the highest priority to develop and test, however, is kinetic impact. In simple terms: fly a spacecraft at high speed into the asteroid so that it is nudged onto a different trajectory.

NASA's DART (Double Asteroid Redirection Test) mission was developed to demonstrate just this approach. Launched in November 2021, DART successfully impacted Dimorphos, the 160m moon of 800m asteroid Didymos, at just over 22,000km/h at 23:14 UTC on 26 September 2022.