NASA smacked a spacecraft into an asteroid – and learned details about its 12-million-year history

Artist impression of ESA's Hera mission to Didymos and Dimorphos. ESA/Science Office

NASA’s DART mission – Double Asteroid Redirection Test – was humanity’s first real-world planetary defence mission.

In September 2022, the DART spacecraft smashed into the companion “moon” of a small asteroid 11 million kilometres from Earth. One goal was to find out if we can give such things a shove if one were headed our way.