DART is a test of NASA’s planetary defence plans. The hope is that an asteroid at risk of striking the Earth could be diverted by hitting it with a spacecraft,nudging it just enough to avoid disaster.

While no known asteroid larger than 140 metres in size has a significant chance of hitting Earth for the next 100 years,it’s estimated only about 40 per cent have been identified to date.

“Now is when the science starts. Now we’re going to see for real how effective we were,” said NASA’s Planetary Science Division director Dr Lori Glaze.

The asteroid was massive – 160 metres in diameter,about the size of a football field – and dwarfed the 570-kilogram spacecraft,but was and tiny in comparison to the Chicxulub asteroid that wiped out the dinosaurs. To make it move,the spacecraft needed to hit itreally,reallyhard – about 6.44 kilometres per second.

The strike still was not hard enough to pinball the asteroid in the other direction. The hope was to move it just slightly off its orbit of its larger sister asteroid Didymos.

A second craft,LICIACube,flew alongside DART to monitor the collision and aftermath,beaming all the data back to Earth. Scientists will spend the next few weeks sifting through the data to see if the mission successfully knocked Didymos off-course.

“This is anArmageddon,Deep Impact andDon’t Look Up all rolled into one,” said Nagle. “We do want to have a better chance than the dinosaurs had 65 million years ago.”

With AP,Reuters.

Liam Mannix’sExamine newsletter explains and analyses science with a rigorous focus on the evidence.Sign up to get it each week.