Heres an interesting fact... People are not actually up "in space", and the reason why they experience the perception of weightlessness, isnt because of the lack of gravity, but because of gravity... its hard to wrap your brain around this fact!! But once you understand that the effect of weightlessness is due to free fall due to gravity, because theyre travelling at 17500mph(approx) horizontally, they technically fall at the rate at which the curvature of the earth falls. For every horizontal foot travelled, they fall one foot vertically, and this mat hes the curvature of the earth, and so the distance from the surface of the earth always remains the same.
In a nutshell, theyre not weightless, just in a constant freefall