The October 26, 2012 MIT News article Paintballs may deflect an incoming asteroid states, "Sung Wook Paek, a graduate student in MIT’s Department of Aeronautics and Astronautics, says if timed just right, pellets full of paint powder, launched in two rounds from a spacecraft at relatively close distance, would cover the front and back of an asteroid, more than doubling its reflectivity, or albedo."
And, "The initial force from the pellets would bump an asteroid off course; over time, the sun’s photons would deflect the asteroid even more."
Paek's plan would maneuver a spacecraft spacecraft close to this asteroid, and then the craft would fire a round of paint pellets, covering one half of the asteroid in a lightly colored powder.
As the asteroid rotates so the opposite side faces the spacecraft, a second round is fired off in the same manner.
The paper of Paek that describes his inventive plan must have a lot of merit because it won him the 2012 Move an Asteroid Technical Paper Competition, which was sponsored by the United Nations’ Space Generation Advisory Council.
The YouTube video "Deflecting an asteroid, with paintballs", seen above, visualizes Paek's plan to save the Earth from destruction by an impending asteroid collision (http://www.youtube.com/watch?v=auSr_aO_gRo).
The caption of this YouTube video states, "In the event that a giant asteroid is headed toward Earth, you'd better hope that it's blindingly white. A brightly colored asteroid would reflect sunlight — and over time, this bouncing of photons off its surface could create enough of a force to push the asteroid off its course."
And, "How might one encourage such a deflection? The answer, according to an MIT graduate student: with a volley or two of space-launched paintballs."