If you visualize any mass (eg Planet Earth) - and draw a number of concentric circles around it - you will have a sketch showing orbits around the globe. Note that even the surface of the Earth is an orbit with zero altitude. My theory is that all the orbits are the same length. Whilst they may appear to be of different lengths - the density of space lessens as you get further out from the center. This means that whilst a space ship appears to be travelling further on the outer orbits - with the space being thinner - the distance travelled through space is the same along all orbits. In some ways this logic reinforces the Flat Earth argument by throwing in space/time variables to support the claims.