A geostationary tether stretches from Earth's equator to a counterweight station whose outward centrifugal pull balances gravity along the cable's length, keeping the whole structure taut. Climber pods use this tension to ride mechanically up and down the tether instead of firing rockets, carrying cargo between the surface and orbit. Because the counterweight orbits slightly faster than geostationary speed, the entire system slowly spins to stay balanced as pods move along it.