🚀 go-pugleaf

> (This is one of the SDI falacies of 'shooting down' ballistic  
missles.  

> They be coming down no matter what.  Like the SCUDs - hitting a  
missle 

> ain't enough.) 

> 


Hmmm. Take your pick:

A) A pile of junk hits your city at terminal velocity, and some of it  
is radiocative.

B) A functioning 500kt warhead explodes at 1000 meters over the city  
centre.

Your statement about the comet is correct, because it's damage is  
entirely due to kinetic energy. The best approach is to change the  
orbital plane enough get rid of the crossing at Earth orbit. If you
were to simply blow it up, you'd better get the debris down to the  
size of Frankian snowballs.

Robert Zubrin figured he could move an outer system asteroid to Mars  
impact with 5 Nerva class engines over 10 years. An environmentalist  
friend of mine (the head of a Rain Forest Action Coalition group in  
an american city) suggested maybe we could kill two birds with one  
stone: make it hit Mars instead. Save one biosphere, get one free :-)