A team of British engineers have designed a real-life spacecraft to save the world from destruction. Their invention, called a "gravity tractor", would be deployed when an orbiting rock is detected on a collision course with Earth.
The spacecraft would intercept the asteroid and position itself to fly alongside it, just 160ft from its surface. From this position, the 10 tonne craft is able to exert a small gravitational force on the rock, pulling the asteroid towards it. By gradually modifying its course, over several years, the gravity tractor is able to slowly shift the asteroid's trajectory enough to ensure it misses the Earth.