NASA has chosen SpaceX for a mission to crash into a "hazardous" asteroid's moon. Tesla chief Elon Musk is all set to begin the mission in June 2021. However, SpaceX won't intercept Didymos' small "moonlet" until October 7, 2022, when the asteroid will be roughly 7 million miles from Earth. The name Didymos is Greek for "twin." The mission won't be cheap, it will cost Nasa $69 million (£53million) to launch.
The best way to prepare for deflecting an asteroid is to do a test run, which is what NASA has planned for its Double Asteroid Redirection Test (DART). "DART is a planetary defence-driven test of one of the technologies for preventing the Earth impact of a hazardous asteroid: the kinetic impactor," Nasa explained. "While Didymos’ primary body is approximately 800 meters across, its secondary body (or “moonlet”) has a 150-meter size, which is more typical of the size of asteroids that could pose a more common hazard to Earth."
DART is set to be the first space mission "to demonstrate asteroid deflection by kinetic impactor on a binary asteroid target." The target in question is called Didymos B, and it's the smaller asteroid of the two Didymos asteroids.
DART uses a technique known as a kinetic impactor. It involves sending one or more high-speed spacecraft into the path of an approaching near-earth object — in this case, an asteroid.