Its probably because nuclear powerplants are too heavy for rockets. Though in theory nuclear powered space craft are an option. == The primary useful product of a nuclear reactor is heat. To use heat generated by a nuclear power plant to drive a conventional rocket isn't very practicle because the power to weight ratio is not very good. And when we wish to rocket ourselves out of the bottom of this gravity well, we need lots of power and minimal weight. The nuclear plant can't deliver the kind of performance that lends itself to the launch of space vehicles.
The two main types of rocket engines are Solid fuel rocket engines and Liquid fuel rocket engines.
W. H. Robbins has written: 'An historical perspective of the NERVA nuclear rocket engine technology program' -- subject(s): Rocket engines
Rocket engines are not air breathing engines and hence they can be propelled into space.
A rocket engine, or simply "rocket," is a jet engine[1] that uses only propellant mass for forming its high speed propulsive jet. Rocket engines are reaction engines and obtain thrust in accordance with Newton's third law. Since they need no external material to form their jet, rocket engines can be used for spacecraft propulsion as well as terrestrial uses, such as missiles. Most rocket engines are internal combustion engines, although non combusting forms also exist.Rocket engines as a group, have the highest exhaust velocities, are by far the lightest, and are the most energy efficient (at least at very high speed) of all types of jet engines. However, for the thrust they give, due to the high exhaust velocity and relatively low specific energy of rocket propellant, they consume propellant very rapidly.
Rocket engine
Model rocket engines are reproductions of rocket engines that are scaled down to a much smaller size than the real thing. They usually don't do anything and are for display purposes.
the rocket is accelerating
a rocket
4
The engines for the space shuttle.
That rocket has NUCLEAR POWER!?
Douglas C. Rapp has written: 'Reliability assessment of thrust chamber cooling concepts using probabilistic analysis techniques' -- subject(s): Thrust, Monte Carlo method, Rocket engines 'High energy-density liquid rocket fuel performance' -- subject(s): Liquid propellants, Rocket engines