It almost sounds as implausible as sending an oil driller to plant a nuclear bomb inside an asteroid over an Aerosmith soundtrack but MIT researchers say shooting paintball pellets at an asteroid could bump an asteroid off its course.
It's not automatic, of course. First of all, we'll need about 20 years lead time to make it happen (I'm hoping we have other solutions than paintball pellets if need be) and we'll need a lot of paintball pellets. How the method, which was developed by Sung Wook Paek, works is that the paintball pellets would literally paint the asteroid in a blindingly white color. Why? Because though shooting the paintball would draw it slightly off course, having sunlight bounce off the asteroid would move it even more over time. According to MIT:
In his proposal, Paek used the asteroid Apophis as a theoretical test case. According to astronomical observations, this 27-gigaton rock may come close to Earth in 2029, and then again in 2036. Paek determined that five tons of paint would be required to cover the massive asteroid, which has a diameter of 1,480 feet. He used the asteroid's period of rotation to determine the timing of pellets, launching a first round to cover the front of the asteroid, and firing a second round once the asteroid's backside is exposed. As the pellets hit the asteroid's surface, they would burst apart, splattering the space rock with a fine, five-micrometer-layer of paint.