>>13943413Hasn't really been tried enough to be sure. If it worked with LCH4 then it could be strictly better because you're still getting 200-250s more ISP than you'd get with a chemical engine, and you'll be saving a great deal on dry mass compared to if you can only do it with LH2, but the technology isn't there because it's speed of development has been cut to practically nothing.
It's not better for Starship for example as a particular vehicle, because Starship is built to propulsive land and to ignite it's engines in atmosphere during takeoff on the way to LEO, a nuclear engine isn't going to be very useful until after the ship is refueled and ready for it's interplanetary flight phase so until that point it would just be dead weight. It will then also be dead weight for propulsive landing on Mars because even in .3g it won't have the TWR so it will be dead weight there too.
Nuclear engines are better for tugs and cyclers, but this assumes that NEP doesn't exist contemporaneously, and if we're going to have atomically powered ships flying around than you'd rather go with NEP because a tug doesn't need high TWR, just high ISP.
For landing on bigger bodies with significant gravity we're still going to have to rely mostly on bipropellant rockets for a while.
