Lunar space elevator and train. Artwork comparing the sizes of a future lunar space elevator (top) and a train locomotive with two box cars. The lunar space elevator is around 50 metres long. It would carry a crew of two in a pressurized compartment at right, with a solar-powered climber mechanism (centre) between two cargo arrays. The climber mechanism uses caterpillar track treads to pull the spacecraft along a ribbon running from the lunar surface to lunar orbit, reaching a speed of around 100 kilometres per hour. This would reduce the costs and fuel requirements to land on and ascend from the Moon.