Given multi-kilometer asteroids like mentioned above, I'm starting to think neither method (fragment/push) sounds viable. The amounts of energy required just seem off the scale? Maybe pushing (multiple?) smaller but still massive enough to have decent kinetic energy into its path would be more feasible. Sorta like pool balls bouncing off each other..I generally end up missing the pocket (earth) when that happens :-)
yeah - how do you keep it out gassing long enough to hit 0.1 m/s though? I would imagine you'd need to nuke it every couple of days or say every week to keep it out gassing long enough to generate that big a change speed?
Hmm - I guess not! According to [1] it would take less then a ton of TNT to accelerate 1 million tonnes (eg like asteroid 12932-zephyr) to 0.1 m/s...So its probably a good thing I'm not responsible for these things!
