Why is it impossible for an astronaut inside an orbiting space station to go from one end to the other by walking normally?

Different Gravities

Explanation:

on Earth we are exposed to a heavy amount of gravity, but in space there is little to no gravity at all and so that's why often times when you're in a spacecraft you hear of zero-g it means Zero Gravity. The only reason we can walk normally is because of the gravity weighing down on our shoulders keeping us planted.