Atomic engines wouldn't really accelerate space development all that much. I don't see a world where telecommunications, computers and robotics advance any fas

Atomic engines wouldn't really accelerate space development all that much. I don't see a world where telecommunications, computers and robotics advance any faster than the one we're in from a 1960s starting point. And we're only just getting to the point where automated manufacturing is advanced enough that space industry seems like almost maybe viable. Even if atomic engines let people in the 70s put more mass into orbit, they wouldn't really have the tech to do much productive with it. Plus, a rocket with a nuke on the other end can still destroy a city if you point it in the right direction. There's no such thing as an unarmed spaceship.