@Terry @oliver Yeah it just lacks the sheer utility of a NTR. This one needs xenon and helium, while a NTR can run on just hydrogen or water, which are abundant in space. Xenon and helium, not so much.

(yes there is helium-3 on the moon but lmao it's at concentrations of at best 50 parts per billion, aka 150 tons of regolith processed per gram of helium-3 😂)