NASA's planetary defence test successfully shifts asteroid orbit

A spacecraft that plowed into a small, harmless asteroid millions of kilometres away succeeded in shifting its orbit, NASA announced Tuesday.

The space agency attempted the first planetary defence test two weeks ago to see if, in the future, a killer rock could be nudged out of Earth's way.

The Dart spacecraft carved a crater into the asteroid Dimorphos on Sept. 26, hurling debris out into space and creating a comet-like trail of dust and rubble stretching several thousand kilometres. It took days of telescope observations to determine how much the impact altered the path of the 160-metre asteroid around its companion, a much bigger space rock.

Before the impact, the moonlet took 11 hours and 55 minutes to circle its parent asteroid. Scientists had hoped to shave off 10 minutes but NASA  administrator Bill Nelson said the impact altered the asteroid's orbit by about 32 minutes.

"This mission shows that NASA is trying to be ready for whatever the universe throws at us," Nelson said during a briefing at NASA headquarters in Washington.

Neither asteroid posed a threat to Earth — and still don't as they continue their journey around the sun. That's why scientists picked the pair for the world's first attempt to alter the position of a celestial body.

The vending machine-size Dart — short for Double Asteroid Redirection Test — was destroyed when it slammed into the asteroid 11 million kilometres away at 22,500 km/h.

The test cost $325 million US.