For a long time you've worry about a possible collision of an asteroid with our planet. Even one at a few hundred of meters can produce serious damage on entire globe. Supposing we are taking in consideration that the asteroids can be larger than that, the situation becomes really serious if it has even at least 1 mile long. Even it doesn't have enough force to affect the planet in the way to producing an explosion, it may be sure that will create at least one minimum position changing on his orbit, resulting in major changing of excessing temperature positive and/or negative. Plants will be devastated immediately, shortly animals will die, followed by rest of us that won't be affect by the impact. In case that an asteroid will approach too much to Earth we can attach an powerful engine and redirect him to another orbit. This technic will work only in case that is only one piece of rock. We create a flote of small and cheap robotics probes, that can investigate in approaching of the planet on the surface of asteroids, checking of composition and structure of them and those probes may explode if necessary too destroying or redirecting them to another orbit. They can work for a few days running on batteries. Nasa has a list with 800 potential asteroids that can represent a danger for our planet because of their orbits. We'll can take 6 probes on a ship and we'll launch them on the destination, but this project will be available from year 2011.