How to protect our planet from asteroids?

An Armageddon in form of big asteroid hitting Earth and destroying all life on Earth is well known topic seen in many popular movies and novels. But this is sadly not just in science fiction sphere but could also turn out to be reality somewhere in future. Therefore scientists are already working on plans to protect our planet from large asteroids. One of the very interesting defensive concepts is the plan coined together by British scientists and engineers in form of spacecraft that could stop large asteroids from hitting the Earth.

They believe how the 10-tonne spacecraft that would rely on the force of gravity would be more than capable to deflect any asteroid years before any potential collision could happen. If we take a look at NASA website we can see that they have recorded 1068 known "Potentially Hazardous Asteroids", and there are probably much more hazardous asteroids in space.

This spacecraft, popularly called "gravity tractor" would operate on following procedure: first it would intercept the asteroid from just 48m away and exert a small gravitational force on it, pulling the asteroid towards it. The pair would then embark on a slightly different orbit, away from the Earth. Some scientists believe these "gravity tractors" could be powered by using solar panels.

Though this defensive theory sounds really good it is still in very early development phase and needs lot more very expensive researches to show its real value. There's also one catch in this whole story, namely that this spacecraft would have to be launched at least 15 years before any predicted collision and would need a team to monitor it from the ground during this time.