Comment Re:Old dreams (Score 1) 108
Of course, the old Orion design has been significantly surpassed by a number of newer designs. Medusa, for example, is much better than Orion - the bombs explode in front of the craft behind a gigantic "parachute", which captures far more of the energy and the long cords on the parachute allow for a much longer, smoother acceleration pulse. The bombs are also able to be detonated much further from the craft, and the craft may be made a lot smaller.
Nuclear thermal - the first version that was being developed called Nerva - allows for "clean" (to varying degrees) fission propulsion from the surface. Or if what you want is high ISP in space, then a fission fragment rocket goes much higher than an Orion or Medusa design (and scales down a lot better)