As far as avoiding a killer asteroid in the future, I have what I consider to be a simple solution. Japan has already demonstrated the technology of landing a spacecraft on an asteroid, so what could be more simple than to land on an asteroid, rotate the landing engine 180 degrees, fire it up and literally push the asteroid into another trajectory? We could strategically post these craft orbiting the moon, Mars, etc. for immediate deployment. Nuclear power for straight-line travel and chemical fuel for rocket control. It's true I probably don't know what I'm talking about, bringing my high school education to bear. But, it sure sounds like the solution to me.