The Planetary Society is supporting an investigation into an interesting approach to the challenge of diverting an asteroid on a path to an earth collision: Laser Bees - We've been working with a team at the University of Glasgow in Scotland to study a new technique which uses concentrated light to gently move an asteroid -- a project we called "Mirror Bees" -- using mirrors on several spacecraft swarming around an asteroid to focus sunlight onto a spot on the asteroid. As part of the initial Mirror Bees project, researchers found that lasers are more effective than mirrors and can be used from greater distances. So, now the project is called "Laser Bees."
The researchers at the University of Glasgow, under the leadership of Massimiliano Vasile, became interested in this approach when they set out to compare nine approaches to planetary defense. To their surprise, one of their results was that Mirror Bees would work more quickly and effectively than all but nuclear warheads. (But unlike the use of nuclear explosions, there would be no risk of breaking a huge asteroid into any number of equally deadly smaller asteroids, nor would the procedure face as many political and bureaucratic hurdles.)