With the development of a manned space station permanently circling the earth, an efficient system is needed to provide both electrical power and propulsion. The electrodynamic tether system being developed by NASA will do this by using a long (e.g. 10 km) conducting tether to interact with the earth's magnetic field. In a low earth orbit, the induced voltage would be on the order of a few tenths of a kilovolt per kilometer of tether. Assuming sufficient electrical contact can be maintained with the ionosphere, a 10 km tether would supply several kilowatts of electrical power. The extraction of power via an associated current results in an I × B force that reduces the orbital speed of the spacecraft. Conversely, if a sufficiently large reverse voltage is applied to reverse the current, then the I × B force will increase the orbital speed and electrical energy will be converted into energy. Consequently, the electrodynamic tether system is expected to perform as a motor/generator system providing a simple, reliable and economical means of efficiently converting orbital energy into electrical energy in a fully reversible process. In addition to a general discussion of the electrodynamic tether system, this article will concentrate on the dynamics of the tether, the proposed electrical contacts or current brushes and the Alfven waves that will carry the charge through space.