This is a 1:16 scale model of NASA's Saturn 1 rocket with a NERVA (Nuclear Engine for Rocket Vehicle Application) upper stage. NASA worked with the Atomic Energy Commission to develop the engine for long-duration crewed missions to Mars. It underwent successful ground testing but was never flight tested or flown in an actual mission.
NASA's Marshall Space Flight Center built the model and donated it to the museum.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.