NASA scientists are preparing to test a system they hope could save the Earth from an apocalyptic wipeout.
The US space agency is planning to crash a rocket into an asteroid to deflect it away from the planet.
They will test the plan next year, launching the Double Asteroid Redirection Test (Dart) spacecraft aboard a SpaceX Falcon 9 rocket from Vandenberg Air Force Base in California.
It will approach the Didymos asteroid, made up of a rock 780 metres wide and a smaller “moonlet” about 160 metres wide.
The Dart will hit it at about 14,700mph, when its electric propulsion system will change its orbit slightly.
The collision is expected to take place when the asteroid gets within 6.8 million miles of Earth. The moon is 240,000 miles away and the sun is 93 million miles away.
A NASA spokesman said preparations for Dart have moved into a critical phase in which the spacecraft’s components and systems are “integrated”.
Jonathan McDowell, an astronomer at the Harvard-Smithsonian Centre for Astrophysics, said: “The reason they are picking that as a target is that it’s a lot easier to measure than, say, the orbit of an asteroid around the sun, which may take several years.”
Although the system is often said to deflect the asteroid’s course, the aim is usually to speed it up or slow it down.
He added: “It’s better to hit it along the trajectory of its motion. If you hit it sideways it doesn’t make much difference.”
Last year NASA awarded Elon Musk’s SpaceX a £53million contract to help in the attempt. SpaceX has deals with NASA to deliver cargo and astronauts to the International Space Station.
On Wednesday a huge asteroid flew past Earth in what NASA called a “close approach”. Dubbed 52768 (1998 OR2), it was around a mile across and passed 3.9 million miles away.
