The sensation of weightlessness, or zero gravity, happens when the effects of gravity are not felt. Technically speaking, gravity does exist everywhere in the universe because it is defined as the force that attracts two bodies to each other. But astronauts in space usually do not feel its effects.
It orbits at an altitude of approximately 248.5 miles (400 kilometers), well above the Kármán Line and the University of Calgary mark. With astronauts experiencing microgravity here, you'd think this would certainly mean that 248.5 miles is safe bet for being above the edge of space, right?