NASA to deflect asteroid in test of 'planetary defense'

In the 1998 Hollywood blockbuster "Armageddon," Bruce Willis and Ben Affleck race to save the Earth from being pulverised by an asteroid.

While the Earth faces no such immediate danger, NASA plans to crash a spacecraft travelling at a speed of 15,000 miles per hour (24,000 kph) into an asteroid next year in a test of "planetary defense".

The Double Asteroid Redirection Test (DART) is to determine whether this is an effective way to deflect the course of an asteroid should one threaten the Earth in the future.

NASA provided details of the DART mission, which carries a price tag of $330 million, in a briefing for reporters on Thursday.

"Although there isn't a currently known asteroid that's on an impact course with the Earth, we do know that there is a large population of near-Earth asteroids out there," said Lindley Johnson, NASA's Planetary Defense Officer.

"The key to planetary defence is finding them well before they are an impact threat," Johnson said. "We don't want to be in a situation where an asteroid is headed towards Earth and then have to test this capability."

The DART spacecraft is scheduled to be launched aboard a SpaceX Falcon 9 rocket at 10:20 pm Pacific time on November 23 from Vandenberg Space Force Base in California.

If the launch takes place at or around that time, impact with the asteroid some 6.8 million miles from Earth would occur between September 26 and October 1 of next year.

The target asteroid, Dimorphos, which means "two forms" in Greek, is about 525 feet in diameter and orbits around a larger asteroid named Didymos, "twin" in Greek.