NASA is set to launch a spacecraft to crash deliberately into an asteroid this week for the first time in history.
The aim is to test-drive whether we can try to alter the space rock's orbit and prevent Earth from another catastrophic event that wiped out the dinosaurs.
Scientists including Stephen Hawking have warned over asteroids being one of the biggest threats to Earth. If they were to collide with our planet, it could cause utter devastation.
NASA has hired Elon Musk's company SpaceX to launch Double Asteroid Redirection Test (DART) to take off on Wednesday at about 6.21am UK time.
It will then crash - or nudge - into the double asteroid between 26 September and 1 October 2022.
The target is an asteroid "moonlet" the size of a football stadium that orbits a much larger chunk of rock - about five times bigger - in a binary asteroid system named Didymos, the Greek word for twin.
The double asteroid isn't heading towards us, but scientists say smaller asteroids are far more common and pose a far greater theoretical threat to Earth in the near term.
The DART mission will test NASA's ability to alter an asteroid's trajectory with kinetic force - crashing a robot spacecraft into it at high speed and nudging the space boulder just enough to keep our planet out of harm's way.
This nudge technique is preferred to blowing asteroids apart in the style of the film Armageddon, because the fragments from such an explosion could continue to imperil the planet.
DART's target is a tiny fraction of the size of the cataclysmic Chicxulub asteroid that slammed into Earth about 66 million years ago, killing most of the planet's animal species.
The moonlet, called Dimorphos, is one of the smallest astronomical objects to receive a permanent name.
But at 525 feet (160 km) in diameter, its size is typical among the known asteroids - rubble-like remnants left over from formation of the solar system 4.6 billion years ago.
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