Cost effective laser based asteroid defense system pitched to NASA

Last year, the University of Strathclyde in Glasgow put forward the idea of using fleets of laser-toting satellites to deflect potentially dangerous objects away from Earth.
Now, Dr. Richard Fork, principal investigator for the Laser Science and Engineering Laboratory at the University of Alabama in Huntsville (UAH), and his team have refined the idea, saying that it’s not only feasible, but could handle anything up to the size of a comet.
If an asteroid 100 m (330 ft) across hit the Earth, it would be a bad day. The impact of a comet such as Halle-Bopp, which is about 70 km (43 mi) in diameter, would make for a very, very bad day. According to Fork, "[The Hale-Bopp comet] is enormous, and if it had been on a collision course with Earth we would have had only two years from the time it was first observed to the time it arrived at Earth. If the comet happened to be on track to hit us, there would have been nothing we could have done. We would have been toast."
Because of the remote, but still present, danger of such an event happening, finding ways to deflect asteroids is of great interest to scientists and engineers. The idea floated by researchers at Strathclyde University in 2012 involves sending a fleet of small satellites that fires lasers at a potentially dangerous asteroid. The purpose wouldn’t be to destroy it in a spectacular Death Star-like explosion, but to nudge it into a new orbit.