It’s a matter of time before a big space rock hits Earth , so Nasa wants to be ready
(Image: Nasa)

Nasa is preparing to launch a mission to smash a ‘planetary defence’ spaceship into an asteroid.

In 2022, a craft called the Double Asteroid Redirection Test (DART) will crash into Didymos – a ‘binary’ asteroid consisting of a small rock orbiting a larger one.

It will be Nasa’s first demonstration of technology that has the potential to protect the whole of humanity from apocalypse asteroids.

Nasa said the mission will launch in 2021 and ‘attempt to pull off a feat so far seen only in science fiction films’.

When DART hits Didymos, scientists will watch closely through telescopes and the craft’s Didymos Reconnaissance and Asteroid Camera for Op-nav (DRACO) camera.

It’s hoped smashing the spaceship into Didymos will either destroy the rock or steer it onto a new course.

These are both options for saving ourselves from asteroids found to be on a collision course with Earth.

DART will crash into Didymos B, which is one of the pair of rocks which make up the binary asteroid.

‘Even though we are performing ground-based observations, we don’t know much about Didymos B in terms of composition and structure,’ said Angela Stickle, DART’s Impact Simulation Working Group Lead from Johns Hopkins University’s Applied Physics Laboratory.

‘We need to anticipate a wide range of possibilities and predict their outcomes, so that after DART slams into Didymos B we’ll know what our measurements are telling us.’

The head of Nasa’s planetary defence division recently suggested that a nuclear strike several hundred meters from the surface of an incoming asteroid could be the best way of averting impact.

According to Lindley Johnson, who leads the division, detonating a nuclear device far enough away from the asteroid would cause it to shift its trajectory.

Nukes might be the only way of saving ourselves from apocalypse asteroids (Image: Nasa)
Nukes might be the only way of saving ourselves from apocalypse asteroids (Image: Nasa)

‘The most effective technique, we think, would be to have an explosion of a nuclear device several hundred meters from the surface of the asteroid,’ he told Politico.

‘The nuclear radiation causes superheating of the asteroid surface and imparts a force on the asteroid in the opposite direction.’

However, simply firing a nuclear missile directly into the asteroid could cause radioactive dust and debris to rain down on Earth.

‘Blow it up into bitty pieces and then you have a bunch of buckshot headed at you,’ Mr Johnson said.

‘You haven’t changed the direction of it. You have just broken it up into pieces, some of which the Earth’s atmosphere may take care of but maybe not at all.’