The world’s first full-scale planetary defence test – NASA’s Double Asteroid Redirection Test (DART) mission – is designed to strike an asteroid and adjust its course.
Today the DART spacecraft is expected to collide with a small asteroid, Dimorphos, at a speed of approximately 6.44 km per second.
Dimorphos is 160 metres in diameter, roughly the size of the Great Pyramid of Giza, and orbits a larger companion asteroid, Didymos.
If successful, the DART mission will show that intentionally crashing a spacecraft into an asteroid is an effective way to change its speed and trajectory. What we learn could be applied in future to protect Earth from potentially hazardous asteroids.