MIT graduate [Sung Wook Paek] proposes theory as a submission to the 2012 'Move an Asteroid Technical Paper Competition' sponsored by the UN...

...Paek’s paintball strategy is based on a solution submitted by the winner of the competition last year, who suggested deflecting an asteroid with a cloud of solid pellets.

Paek’s strategy is also based on using pellets, but filling them with paint in order to cover the asteroid in a fine, five-micrometer-layer of paint.

The MIT website explains: “Adding paint to the pellets to take advantage of solar radiation pressure — the force exerted on objects by the sun’s photons. Researchers have observed that pressure from sunlight can alter the orbits of geosynchronous satellites, while others have proposed equipping spacecraft with sails to catch solar radiation, much like a sailboat catches wind.”

The solution is certainly not quick - Paek estimates that it could take up to 20 years for the effect of solar radiation pressure to pull the asteroid off its trajectory.

Paek based his proposal on the 27-gigaton rock 'Apophis', which it is thought could come close to Earth in 2029, and then again in 2036. The huge asteroid, which has a diameter of 1,480 feet, would require five tons of paint to cover it Paek says.

The timing of the firing of pellets, which may have to be manufactured in space (on the International Space Station for instance) because of the danger of them fracturing during takeoff from Earth, would be based upon the asteroid's period of rotation. 

Paek also suggests that the pellets could contain aerosols, instead of paint, which when shot at the asteroid would: “impart air drag on the incoming asteroid to slow it down.”

Video: Deflecting an asteroid with paintballs