Sorry, I cleared the page before I got the idea to write this post. Therefore, there's no
link to that page. It said that Elon Musk was considering nuke rockets for his trips to
Mars. I don't know if that's true or not, but if so, it would be good news and bad news.
The good news is that it may be more realistic than using chemical rockets. Reason being
that you're going to need a crap load of fuel to make the trip to Mars. A nuke rocket will
help with that in reducing the amount of fuel needed for the trip. Also, if you can get
the fuel up there and in great quantity, you can slice the time down for the trip. This
might make a roundtrip possible if it were to be short enough in duration.
There might be a speculation alert necessary there in that last paragraph. I don't know if
that's true or not, but if your launch windows are two years apart, it is for a reason. The
reason is that the Earth and Mars are close enough together in their orbits to make the
distance reasonable and compatible with a feasible trajectory.
If memory serves, it takes eight months to get there with chemical rockets. If you can cut
the transit time down sufficiently, that transit time could be cut into half at least. (That
is speculation, I don't know if that is possible.)
I do know that the ISP of a nuke rocket is twice that of a chemical rocket, so it would need
less than half the fuel ( or so I would think). That much is the good news.
The bad news is that you have to develop an entirely new rocket and find a way to get it
into orbit. It couldn't be launched from the ground because... radioactivity. In space,
presumably, you could light it up without sending regulatory agencies into hysterics.
Such a rocket is definitely feasible, and it could be a boost stage that wouldn't be
launched from the ground. Maybe like a space tug or something that would take a starship
along at higher velocities for a shorter trip to Mars.
A cargo carrying Starship could bring one up, and then its fuel tank. It could fill the
tank with another launch, and then off they would go.
An eight month trip in weightless conditions would be tough on the human body. Something
has to be done to lessen that impact. This could be an alternative. Another alternative
would be to spin it up with artificial gravity.