Animation of a futuristic space elevator, linked to an orbital ring. Space elevators present a novel way of getting personal and materials into orbit. Traditionally they are 'cables' tethered to the ground and anchored to a counterweight in geostationary orbit. But this makes them 36,000 km (22.000 miles) long, and no known material can support its own weight at this length. An orbital ring uses a different approach. A magnetic ring encircles the entire Earth, and it can be placed at any orientation and altitude - even as low as 100 km. It moves slightly faster than orbital velocity, so that it remains taught. Theoretically, once this infrastructure is in place, objects can be magnetically levitated above the ring, or hang from it, suspended by electromagnets, and they would stay in place relative to the ground (if the orbital ring is above the Earth's equator.) A cable could be suspended from this, allowing vehicles to ascend and descend. This animation shows the interior of an imaginary 'sky train' destined for an orbital ring at an altitude of 300 km. Each train has twenty individual 'carriages' which each have three levels. Moving at 150 km per hour it could reach the ring in as little as two hours.