And I'll back away. I'll let go of him. And he will orient himself using the hand controller and then try to actually fly as if he were doing a self-rescue. In reality, the trajectory of an untethered astronaut would play a role in how difficult a self rescue might prove to be. But if an astronaut moved away below the station toward Earth or above it toward deep space, the level of difficulty could increase dramatically.
Orbital velocity depends only on the radius of an object's orbit.
The closer an object is to the body it is orbiting, the faster it moves. The farther away, the slower. An astronaut moving away toward Earth below the station would move faster as he or she lost altitude, pulling slowly but surely ahead of the station. The situation would be reversed for an astronaut moving away from the shuttle toward deep space. In either case, aiming themselves correctly to fly back to the station could prove challenging.