>>16
Ok, but if a 20 ton craft isnt large enough... What about a really heavy massed asteroid. If the Craft is too light, it aint gonna do anything except hit earth with the rock. There are too many things. A nuclear launch system is much less complex than a modern space launch system.
I understand there was much thought, and it is rather plausible. but you must also look at what could go wrong. Say the engines fail before it gets off the ground, mid air explosion, system failure on way to asteroid. Anything can happen, and if thats the case, we cant just go, oh... lets try again. in this situation we get one shot at it.