Orbital Tether

A orbital tether, commonly referred to alternatively as a "space elevator", is the term given to an immense structure which is used to ferry large loads of materials into space. Orbital tethers generally consist of large structures of carbon nanofiber which span straight up from the ground, thousands of kilometers high, ending at stations in space. Vehicles using the structure derive their power from strands of superconducting material.

Introduction
Space elevators are a common construction on most major worlds, primarily for the cheap transportation of goods and people.

Description
A space elevator is a structure designed to transport and ferry different materials from a planet's surface into space and onto a platform. The base concept of a Space elevator consists of a cable attached to the surface on the equator and reaching outwards into space. By positioning it so that the total centrifugal force exceeds the total gravity, either by extending the cable or attaching a counterweight, the elevator stays in place in geosynchronous orbit. Once moved far enough, climbers are accelerated further by the planet's rotation.

The most common proposal is a tether, usually in the form of a cable, that spans from the surface to a point beyond geosynchronous orbit. As the planet rotates, the inertia at the end of the tether counteracts gravity and keeps the tether taut. Vehicles can then climb the tether and escape the planet's gravity without the use of rockets. The engineering of such a structure requires an extremely light but extremely strong material (current estimates require a material ~2 g/cm³ in density and a tensile strength of ~70 GPa). Such a structure could permit delivery of great quantities of cargo and people to orbit, and at costs only a fraction of those associated with current means with very little to no danger.

Size
The space elevator is gigantic, reaching into thousands of kilometers in height. An orbital tether's center of gravity must be above or at a point of geosynchronous orbit above the body it is located on. Because geosynchronous orbit above Earth is quite high, (35,900 KM above the surface) the height of the elevator would be twice the distance from the surface to the point of geosynchronous orbit. This gives orbital tethers (Because the same rule would apply to them all) an average height of 70,000 kilometers above the Earth's surface.

Structure
Space elevators vary in size and shape, but they are all typically composed of the same raw material. Meshed together as a complex composite of intertwining nanofibers, these ingredients form a series of massive cords and rings several hundred meters wide. They bind to a grounded set of polycrete anchors larger than most buildings which hold the elevator's structure in place while the planet spins on its axis. The zenith of the elevator, commonly known as the "orbital" or "terminus" is then pulled taut by the planet's rotational inertia, sliding into geosynchronous orbit thousands of kilometers above the planet.

Power
The top ring is lined with a photovoltaic array, while the towers carry the energy it supplies to the surface. The solar energy system can also transmit power wireless to mobile units via microwave transmissions,

Climber
An orbital tether cannot be an elevator in the typical sense (with moving cables) due to the need for the cable to be significantly wider at the center than at the tips. While various designs employing moving cables have been proposed, most cable designs call for the "elevator" to climb up a stationary cable.

Climbers cover a wide range of designs. Climbers must be paced at optimal timings so as to minimize cable stress and oscillations and to maximize throughput.

Passenger Climbers
These small container-like craft capable of moving up and down a orbital tether's strand, transporting large numbers of civilian personnel offworld or down from an orbiting platform. These lighter climbers can be sent up more often, with several going up at the same time. This increases throughput somewhat, but lowers the mass of each individual payload.

Cargo Climbers
In high-capacity cargo elevator systems, the cargo containers are also compatible with ground-based mag-lev train lines and they can be effectively converted into freighters by attaching a propulsion pod to them on the top of the tether. These freighter were usually simple cargo containers attached magnetically to a propulsion pod which contained the faster-than-light drive and sub-light maneuvering systems. These containers could travel up and down space elevator strands, allowing for fast loading and management of cargo. Once on top of the elevator, the propulsion pod activates, effectively turning it into a slipspace-capable freighter.

Counterweight
In order to establish a counterweight most orbital tethers use a captured asteroid or a space station

Safety
Due to the size of the space elevator, the safety of such a structure is an obvious concern. The catastrophic effects of a orbital tether's collapse were witnessed multiple times during the Borderland Blitz, when invading Klingon warships or Orion demolition teams destroyed orbital tethers to prevent their use in moving troops or fighters. If the orbital counterweight is destroyed or the tether is cut near the top, the whole cable will fall, usually wrapping itself around the planet. If the tether is cut halfway up, the upper portion will rise up and remain in orbit while the lower part will drape around the planet. The same will occur if the tether breaks quarter way up. In case the break occurs at or near the anchor point on the planet surface, the whole tether will rise upward and end up in an unstable orbit around the planet. Due to the safety concerns, tether cities are almost always designed with the possibility of a catastrophe in mind. The cities are often compartmentalized into multiple symmetrical sections, to minimize the death toll and property damage in case anything were to happen to the elevator. However, contrary to popular belief that the collapse of a space elevator will cause massive planetary destruction, the tether itself will not cause any significant damage at all. The lightweight construction of the tether allows for air resistance to negate the effects of gravity. Instead, it will be the support structure that surrounds the tether that causes most of the damage.

Known Orbital Tethers
Avali

Barecht

Bensonia

Botchok Earth
 * Orion-Barbo Space Elevator
 * Singapore Interplanetary Tether

Gannat

Luna Magnus Mars Ugoan Waal
 * Eagle Orbital Tether
 * Württemberg Station
 * Utopia Plantia
 * Hoart Orbital Tethers