Space Tether

Space Tether

Space tethers are cables, usually long and very strong, which can be used for propulsion, stabilization, or maintaining the formation of space systems by determining the trajectory of spacecraft and payloads. Depending on the mission objectives and altitude, spaceflight using this form of spacecraft propulsion may be significantly less expensive than spaceflight using rocket engines.

Four main techniques for employing space tethers are in development:

Electrodynamic tether

This is a conductive tether that carries a current that can generate thrust or drag from a planetary magnetic field, in much the same way as an electric motor.

Momentum exchange tether

This is a rotating tether that would grab a spacecraft and then release it at later time. Doing this can transfer momentum and energy from the tether to and from the spacecraft with very little loss; this can be used for orbital maneuvering.

Tethered formation flying

This is typically a non-conductive tether that accurately maintains a set distance between space vehicles.

Electric sail

A form of solar wind sail with electrically charged tethers that will be pushed by the momentum of solar wind ions.

Many uses for space tethers have been proposed, including deployment as space elevators and for doing propellant-free orbital transfers.