NASA has selected the ride for its Double Asteroid Redirection Test (DART) mission, awarding SpaceX the US$69 million launch contract. If all goes according to plan, DART will lift off atop a Falcon 9 rocket from Space Launch Complex 4E at Vandenberg Air Force Base in California in June 2021 – the first step on a voyage intended to demonstrate how a spacecraft collision can alter the trajectory of an asteroid.

Part of the joint Asteroid Impact & Deflection Assessment (AIDA) project with ESA, DART will travel to the binary asteroid Didymos, which is made of a large, rocky, S-type asteroid called Didymos A that has a diameter of about 780 m (2,500 ft), and the smaller Didymos B of unknown composition that's about 160 m (530 ft) across.

After launching, DART will power its way to rendezvous with Didymos using its solar electric propulsion system. In October 2022, it will zero in on Didymos B and impact it at high speed while it's still 11 million km (7 million mi) from Earth. Meanwhile, an ESA probe will observe the event and measure the degree of deflection caused by the impact.

By measuring this deflection, scientists will be able to assess the effectiveness of such a kinetic impact and refine the technique. Such a deflection may be very small, but if it is made far enough from Earth, it could mean the difference between a devastating strike or a safe near miss.

Source: NASA