I've been looking into some of the various treaties regarding the use of nuclear explosions, and I'm having trouble figuring out some of the gray zones; The United States and Russia have both signed treaties http://en.wikipedia.org/wiki/Comprehensive_Nuclear-Test-Ban_Treaty" [Broken] So my question is whether or not http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29" [Broken] would be considered peaceful? The limited test ban treaty bans "nuclear testing" in atmosphere and in space, but so far as I can tell there is no treaty either expressly allowing or banning such a practice. Are there major engineering challenges that simply can't be overcome, or is the obstacle to such a program political? The wiki article on the orion project states that the "partial test ban treaty is generally acknowledged to have ended the program," so does that mean this use falls under bans included in that treaty? On an engineering note, how does nuclear pulse propulsion compare to, say, a nuclear rocket, or other fission reactor powered designs?