Nuclear Space means using things like rockets and spacecraft that are powered by nuclear energy instead of things like gasoline or electricity. Nuclear energy is energy made by splitting apart atoms to release energy, and it can be very powerful and efficient. To use it in space, special reactors are built that are able to safely store and control the energy so that it can be used to power rockets, satellites, and other spacecraft. Nuclear energy is much more efficient than other sorts of energy, so it makes space exploration easier and faster.