Electrodynamic (ED) tether is a long conducting wire extended from spacecraft. It has a strong potential for providing propellant less propulsion to spacecraft in low earth orbit. An electrodynamic Tether uses the same principle as electric motor in toys, appliances and computer disk drives. It works as a thruster, because a magnetic field exerts a force on a current carrying wire. The magnetic field is supplied by the earth. By properly controlled the forces generated by this electrodynamic tether can be used to pull or push a spacecraft to act as brake or a booster. NASA plans to loose energy from Earth's atmosphere with a tether act as part of first demonstration of a propellant-free space propulsion system, potentially leading to a revolutionary space transportation system. Working with Earth's magnetic field would benefit a number of spacecraft including the International Space Station.Tether propulsion requires no fuel. Electrodynamic Tether is completely reusable and environmentally clean and provides all these features at low cost.
Attachment for detail report on Electrodynamic Tethers is given below