 Once deployed, the tether would be ascended repeatedly by mechanical means to orbit, and descended to return to the surface from orbit.On Earth, with its relatively strong gravity, current technology is not capable of manufacturing tether materials that are sufficiently strong and light enough to build a space elevator.However, recent concepts for a space elevator are notable for their plans to use carbon nanotube or boron nitride nanotube-based materials as the tensile element in the tether design.