A year from now, the U.S. Navy hopes to launch a pair of small satellites that are able to harvest electrons from space and use them and Earth's magnetic field as a propulsion system.

"It's like a giant electric motor in space," said Shannon Coffey, who heads the Tether Electrodynamics Propulsion CubeSat Experiment at the Naval Research Laboratory. "What are the components of a motor? Current in wires and a magnet."

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