"Dude, the Orion project would solve all our problems. Why prepare astronauts for a six-month trip to Mars when the Orion NPP ship could get them there in a matter of weeks? But we can't use it! It uses NUKES! So what? At last, our nuclear weapons would serve a practical purpose.
Edit: To add insult to injury, if I remember correctly this project was theoretically feasible and safe with 1960s technology."
Orion was (and still is) a really cool idea for travel to the outer planets, however they never did lick the two biggest problems with the design.
1. The crew would die of radiation sickness. Even if you placed them behind a massive wall of lead, the most energetic particles released by each nuke would still get them.
2. For the design to be really effective, the ship needs to be very VERY massive (thousands of tons, like as big as an aircraft carrier). So you either construct it on Earth and let it's first few hundred nukes go off in the atmosphere (believe it or not, that was the original plan, and the expected addition to the world's total cancer rates was about 1-3% percent), or you construct it in orbit. But we don't currently have a cheap enough method of orbital insertion or construction.
Now, if we had a space elevator and a new form of radiation shielding (or new nukes that somehow didn't emit as much radiation), then we could actually build Orion ships in orbit to go to Mars in a matter of weeks and the outer planets in a few months.
The argument about "no nukes in space" treaty, while it was used against the original design team, was always secondary to these other problems. And considering how we've already pulled out of most of the arms control treaties of the period (not a smart move, but that's another argument for another day) I doubt it would matter to American public opinion if we did use nukes for an Orion ship.
Both NASA and the RSA have been quietly re-funding nuclear-powered rocket development as a possible Mars exploration system, but that wouldn't involve bombs going off, instead a nuclear core would be used to heat propellant. NASA is still deciding if it should use one of these systems to get to Mars.
The news from SpaceX is amazing though, if the succeed in making their design safer private industry is really going to take off in Earth orbit. The cost reductions make all kinds of new ideas profitable (for instance, small orbital hotels that charge a fraction of what the Russians are charging for a stay on the ISS).
/nerd chad complete