NASA announced it has entered the design phase of its Double Asteroid Redirection Test (DART).
The test will consist of crashing a spacecraft into a non-threatening asteroid to determine the efficiency of the kinetic impact redirection technique.
The target asteroid is called Didymos B and is about 160 metres wide. Didymos B orbits a larger asteroid called Didymos A, which is around 780 metres wide.
The nature of the binary system will allow Earth-based observatories to measure the effect of the impact by measuring differences in the orbit of Didymos B.
The target asteroid will have a distant approach to Earth in 2022 and 2024.