I believe you might be a bit pessimistic. The USA studied nuclear ramjets in the 1950, as well as thermal nuclear rockets. Russia has a nuclear propelled missile [0].
Much as I like nuclear power for deep space stuff, even put them in the novel I've never finished writing, they're politically unacceptable* where they're most useful: take-off.
Basically all the people going "What if 9/11 was done with a flying Chernobyl?"**, some of whom are concerned voters, some of whom are the engineering team, some of whom are the foreign politicians who threaten to put sanctions on you.
Once you get to interplanetary, ion drives take away most of the advantage, because of how many people are willing to put a few extra years on a mission in exchange for not having to care about the risks.
Still, incredibly useful if you can get past all that.
* outside of warfare
** Which is essentially also something that happens in my novel, as the intersection of accident with Newton's first law
Please finish your novel, it looks very interesting!
> "What if 9/11 was done with a flying Chernobyl?"
I guess it's a PR problem, particularly with the perspective to have dozen of Starship rockets launched every year.
What do people prefer? A rocket that works within reasonable technological limits (a nuclear rocket with chemical first stage) or a monster rocket that works at the edge of what is physically possible (Starship)?
The issue, politically and for the public, is not so much nuclear for space travel, it's launching it into space, IMHO. I don't think anyone cares too much if you say that you will use nukes to accelerate your spaceship to Mars (as long as they can trust that this is indeed what you are doing) until you say that this means you will need to build those nukes on Earth and, especially, to load them onto rockets to launch them into space because what happens if it crashes or explodes?
> Please finish your novel, it looks very interesting!
Thanks, I've had similar positive responses from many people… unfortunately, spread over the last decade, because I keep finding it hard to tie all the bits together.
I'm better at world-building than plot, I have discovered.
Basically all the people going "What if 9/11 was done with a flying Chernobyl?"**, some of whom are concerned voters, some of whom are the engineering team, some of whom are the foreign politicians who threaten to put sanctions on you.
Once you get to interplanetary, ion drives take away most of the advantage, because of how many people are willing to put a few extra years on a mission in exchange for not having to care about the risks.
Still, incredibly useful if you can get past all that.
* outside of warfare
** Which is essentially also something that happens in my novel, as the intersection of accident with Newton's first law