Impacting an asteroid, before an asteroid impacts us

NASA’s Double Asteroid Redirection Test, DART, is currently hurtling through space towards a pair of gravitationally bound asteroids in orbit around the Sun. The binary asteroid system is known as Didymos, and the smaller ‘moonlet’ of the pair, Dimorphos, will be the first asteroid in the Solar System to be the target of a humanmade ‘kinetic impactor’.

In the aftermath of the impact, ESA’s Hera mission will fly to the stricken rock to carry out an in-depth analysis of the crater formed, the mass of the asteroid and a great deal more, turning this grand experiment into an understood and repeatable planetary defence technique.

All this, however, depends on DART hitting its target. The spacecraft will be hurtling through space at 22 000 km/h at a distance of 11 million kilometres from Earth, closing in on a moving object about the same size as the Great Pyramid of Giza – so this is no easy feat.