A team of British scientists and engineers are taking a look at gravity as one way to protect the Earth from asteroids and objects from outer space.

Instead of sending shuttle crews to blow an approaching asteroid up, British astronomers at the Astrophysics Research Center are planning to build a 10-ton "gravity tractor" spacecraft that will influence the object's trajectory. However the process will take some time -- a craft will have to be launched 15 years in advance to really have an effect -- but, once the tractor arrives, it will hover close by an asteroid and gently guide it along a different path.

But the high cost implications mean that before the device could be made, it would have to be commissioned by a government or a group of governments working together.

Source: BBC News