A space elevator is a theoretical system using a super-strong ribbon going from the surface of the Earth to a point beyond Geosynchronous orbit. The center of gravity of the ribbon would be exactly in geosynchronous orbit, so that the ribbon would always stay above the anchor point. Vehicles would climb the ribbon powered by a beam of energy projected from the surface of the Earth. Building a space elevator requires materials and techniques that do not currently exist. A variety of Space Elevator competitions have been held in order to stimulate the development of such materials and techniques.
Space elevators were first conceived in 1895, but until the discovery of carbon nanotubes, no technology was envisioned that could make them possible. Building an actual elevator is still out of reach, but the directions for research are clear. This makes the area ripe for incentive prizes like the X Prize, and prizes and competitions have been set up since 2005[1] to encourage the development of relevant technologies. There are two main areas of research remaining, and these are where the competitions focus: building cables ("a Tether challenge"), and climbing and descending cables ("a Power Beam challenge").
In a Power Beam Challenge, each team designs and builds a climber (a machine capable of traveling up and down a tether ribbon). In a Tether challenge, each team attempts to build the longest and strongest cable. In the Power Beam challenge climber carry a payload. Power is beamed from a transmitter to a receiver on the climber. With each competition, the tethers reach higher altitudes, and the climbers are expected to climb further. Each competition can have minimum lengths and maximum weight per meter for cables, and minimum speed and distance goals for climbers.