The dinosaurs learnt it the hard way 66 million years ago, when an asteroid 10km wide collided with the Earth, causing vast destruction and long-term global changes that wiped out three-quarters of life on Earth, and ended the reign of the great dinosaurs.
A similar impact today would have incalculable consequences. But have we found a way to prevent it? Scientists will be gathering the answers as you read this, if NASA’s plan for September 26 has gone smoothly, with the final stage of a 10-month space voyage seeing a space-craft the size of a chest freezer slammed into the moon of a distant asteroid at a speed of at least 21,000km/h. The space-craft is DART (short for Double Asteroid Redirection Test), a 610kg missile on a suicide mission
