US space agency NASA is preparing to launch a satellite that will deliberately crash into an asteroid, aiming to alter its course in the first mission of its kind.
The planetary defence probe, powered by a Falcon 9 rocket made by Elon Musk's SpaceX, is set to take off on Wednesday from Vandenberg Space Force Base in California.
It is due to smash into the Dimorphos asteroid in October next year, in what has been dubbed the Double Asteroid Redirection Test (DART).
Dimorphos, a moonlet whose diameter measures about 160 metres, does not pose a danger to Earth, according to NASA's calculations.
The mission is designed to ensure that even after the impact, there would be no risk to the planet.
The European Space Agency mission Hera is scheduled to launch a mission in 2024 to study the impact in greater detail.
NASA hopes the mission, costing about $US330 million ($A457 million), will deliver insights about how to protect Earth from any approaching asteroids.
Scientists are not aware of any asteroids currently threatening Earth but have identified some 27,000 asteroids in our planet's proximity, with some 10,000 of them measuring more than 140 metres in diameter.
© DPA 2021