From: desmondkavanagh@gmail.com   
      
   As a previous poster wrote, specific impulse is the way to go. $/kg in orbit   
   basicly. Long time since I looked at this, but if memory serves, for   
   relatively low masses (and without safety considerations) unsymmetrical   
   dimethylhydrazine (UDMH) + nitrogen    
   tetroxide (N2O4) or LOX is a good combination.   
      
   For large masses (hundreds of thousands of tons, the more massive the smoother   
   the ride), Orion is a no brainer, but the greenies and PC'ers shut that down   
   half a century ago. No oxidiser, just reaction mass.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)