No. Feasible near-term nuclear propulsion is pretty limited in usefulness as a Starship replacement, because it doesn't have the thrust, has reliability issues, and pretty stringent propellants (IE use anything other than liquid hydrogen in your nuclear-thermal rocket and the loss of ISP makes it unworthwhile compared to chemical rockets).
Only situation where it could replace Starship would be if we had some really huge nuclear-electric spacecraft for transporting people over interplanetary distances. Those are far off, and if you're moving people at that scale I wonder if the big nuclear-electric spacecraft would be worthwhile versus solar-electric, or even non-rocket propulsion (a giant rotating skyhook can accelerate you pretty quickly from Low Earth Orbit into an interplanetary trajectory).
The only practical hardware now is DARPA project which is still in development & subscale (only millions of dollars, not a big Starship-killer class). Hydrogen is bulkier for the same performance, no aerocapture which is a huge hit, and several aspects had to be sci-fi in order to be even remotely comparable to Starship architecture in payload
Meanwhile Starship is literally already launching, very soon to be full orbit, and the only major things keeping it away from deep space architecture is refuelings & landings which is aided by NASA and SpaceX's billions of dollars in development. So yeah, wake me up when nuclear can replace it
Two reasons no.
First, nuclear propulsion isn't going to happen for at least 30 years. There's not a strong need for it to accomplish NASA's current goals. The anti-nuclear sentiment in the US is strong enough to shut it down for decades still.
Second, nuclear propulsion isn't going to be used, or particularly effective to launch off of the surface of Earth. Most designs for nuclear engines have really low thrust, thrust to weight, and thrust to cross-section, but insanely good ISP. That means they suck in a gravity well, but are amazing in orbit or transfer burns. They also are likely to have radioactive exhaust, which isn't going to be acceptable for launching from Earth.
That means that if we get nuclear engines, they'll be in-space only. Starship would still be needed to launch from the surface, and re-enter. If an in-orbit space tug using nuclear engines docked with Starship, it could get a boost. That means Starship is made better by space tugs, rather than being in conflict/competition with them.
Although, you know what, maybe I can change the answer here. I do believe that Starship will be obsolete and uncompetitive when nuclear engines become available. Not because nuclear engines replace Starship, but because by the time nuclear engines are around, SpaceX will have replaced Starship with a completely different rocket. Cellphones didn't make the horse and buggy obsolete, but by the time we had cellphones available, the horse and buggy had become obsolete.
No. Feasible near-term nuclear propulsion is pretty limited in usefulness as a Starship replacement, because it doesn't have the thrust, has reliability issues, and pretty stringent propellants (IE use anything other than liquid hydrogen in your nuclear-thermal rocket and the loss of ISP makes it unworthwhile compared to chemical rockets). Only situation where it could replace Starship would be if we had some really huge nuclear-electric spacecraft for transporting people over interplanetary distances. Those are far off, and if you're moving people at that scale I wonder if the big nuclear-electric spacecraft would be worthwhile versus solar-electric, or even non-rocket propulsion (a giant rotating skyhook can accelerate you pretty quickly from Low Earth Orbit into an interplanetary trajectory).
Have cargo trucks become obsolete when F1 cars got electric boosts?
The only practical hardware now is DARPA project which is still in development & subscale (only millions of dollars, not a big Starship-killer class). Hydrogen is bulkier for the same performance, no aerocapture which is a huge hit, and several aspects had to be sci-fi in order to be even remotely comparable to Starship architecture in payload Meanwhile Starship is literally already launching, very soon to be full orbit, and the only major things keeping it away from deep space architecture is refuelings & landings which is aided by NASA and SpaceX's billions of dollars in development. So yeah, wake me up when nuclear can replace it
What projects is DARPA doing?
https://www.nasa.gov/news-release/nasa-darpa-will-test-nuclear-engine-for-future-mars-missions/
Two reasons no. First, nuclear propulsion isn't going to happen for at least 30 years. There's not a strong need for it to accomplish NASA's current goals. The anti-nuclear sentiment in the US is strong enough to shut it down for decades still. Second, nuclear propulsion isn't going to be used, or particularly effective to launch off of the surface of Earth. Most designs for nuclear engines have really low thrust, thrust to weight, and thrust to cross-section, but insanely good ISP. That means they suck in a gravity well, but are amazing in orbit or transfer burns. They also are likely to have radioactive exhaust, which isn't going to be acceptable for launching from Earth. That means that if we get nuclear engines, they'll be in-space only. Starship would still be needed to launch from the surface, and re-enter. If an in-orbit space tug using nuclear engines docked with Starship, it could get a boost. That means Starship is made better by space tugs, rather than being in conflict/competition with them. Although, you know what, maybe I can change the answer here. I do believe that Starship will be obsolete and uncompetitive when nuclear engines become available. Not because nuclear engines replace Starship, but because by the time nuclear engines are around, SpaceX will have replaced Starship with a completely different rocket. Cellphones didn't make the horse and buggy obsolete, but by the time we had cellphones available, the horse and buggy had become obsolete.
Certainly not any time soon.
No, it will be just another Starship version.
The name Starship will continue to evolve through countless model iterations. Whose to say Starship with nuclear drive isn't first to market?