P.P.S. Hmm - actually, if the object is that big...would we even have enough nukes/energy to break it up. Seems like either way (breakup/push) we're going to be limited by the amount of energy we can deliver compared to the mass of the asteroid? Oh! also, would a nuke actually keep stuff out gassing long enough before it cools back down? how long would you need to have that tiny lil push going on before it made any practical difference? thats a lot of mass to try and push ??