PMG

PMG [NASA]

NASA-sponsored PMG (Plasma Motor Generator) was a 500 m long electrodynamic tethered system deployed from the Delta-7925 second stage with the primary goal of testing power generation and thrust by means of an electrodynamic tether system.

This mission was the first example of a propulsion system for space transportation that did not utilize any propellant (and mass ejecta) but rather achieved propulsion by converting orbital energy into electrical energy (deorbit) or electrical energy into orbital energy (orbit raising). In summary, an electrodynamic tether can operate as a magnetic thrusters around planets with a magnetic field and a ionosphere. PMG proved, for a short duration, the basic principles of magnetic propulsion.