Nuclear powered engines were deemed to be potential weapons for treaty purposes. Either this never gets adopted, or a later treaty reverses this policy.
How about... Instead of the ISS the advanced space powers in the late 90s agree on a common mars mission and that part of the treaties gets cut out with mutual agreement?
Works for me. :-D
No, "Nuclear Engines" like NERVA and DUMBO were NOT considered weapons and were and are exempted from such treaties. Nuclear power reactors are also exempt which is why the USSR tended to use them a lot.
Now let me be clear, (I swear I'd written this before but it bears repeating) Orion (boom-boom) pulse units ARE nuclear weapons. They are designed and built just like them the only differences it they are designed to project a majority of their force and generated plasma, (hence why they are designated "External Pulsed Plasma Propulsion" units or EP3: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000097368.pdf) in one direction. They are nuclear shape charges but make no mistake in order to produce them on the scale needed for even ONE (1) Orion type ship you have to throw ANY possibility of nuclear weapons control and likely proliferation limitation out the window!
While the pulse units are not 'good' nuclear weapons you will still need to streamline and expand what amounts to the ability to make dozens of nuclear weapons a year to into the ability to make THOUSANDS of nuclear weapons a year! Think about that for a second. You need hundreds of pulse unit to get from Earth into orbit, close to a thousand to get to the Moon and likely a couple of thousand to get to Mars, etc. And so you are making thousands of pulse units per year. Thousands of nuclear weapons and how do you ensure that ALL of those are going to space? Even more so keep in mind that Orion, despite what those working on it may have wished, was essentially getting military (Air Force) support in the hope of using it to put Orion Battleships (http://www.thespacereview.com/article/2714/1) with hundreds of actual nuclear weapons onboard into Cis-Lunar space as a deterrent system.
And since there would be no way of keeping THAT a secret the USSR would have no choice to do the same.. Or worse strike before it became available. And like I said, kiss ANY hope of limiting nuclear weapons goodbye since you HAVE to put into place a system that can make a thousand warheads per year for years on end...
Kennedy was horrified at the concept all right and with good reason! (Now if I can ever get the point where I finish writing "Mac and Orion"... but frankly I can't see my way past the obvious 'cliffhanger' since even if McNamara justifies it to Kennedy, then Kennedy is still going to have to make the 'political' decision and it doesn't seem to me that opening the Solar System will be worth the cost it may entail)
I love me some Orion goodness but once you take a step back and look at the times and places I'm not seeing anyone capable of making that decision given the circumstances... Now if you have a killer rock coming your way the circumstances are obviously changed...
Randy