There is one thing I am very concerned about this plan. I've read that one of the plans to deflect a potential asteroid heading for earth would be to park a small space craft in position next to the asteroid, and let it follow the asteroid for an extended period. This would allow for the small gravitational force from the spacecraft to change the orbit of the asteroid. What if our testing somehow changes the orbits of these asteroids, resulting in a new trajectory that will eventually bring the asteroid crashing into earth? It seems to follow that if we can manipulate the orbit enough to make one heading for earth to miss earth, we could also inadvertently cause one that was going to miss earth to hit earth.

I don't know the answer... is it to leave well enough alone, and not try to gain more knowledge? Or, is it to be sure we can deflect the asteroid before we accidentally set one on a collision course?

Just something to think about.