One upon a time there was a project called ProSEDS. It was a little experiment that would have demonstrated a new type of space propulsion using a long, thin conducing wire called a “space tether.” The neat thing about space tethers is that they can propel a spacecraft without using any fuel – they aren’t rockets. Tethers can propel a spacecraft by using something called the Lorentz Force, which is generated when a wire carries a current in the presence of a magnetic field. The electrons that make up the current carry an electric charge and are deflected by the Earth’s magnetic field. Since they are trapped in the wire, the entire wire is deflected (pushed), pulling the spacecraft along for the ride.
The ProSEDS experiment would have shown that these electric forces can be used to spacecraft propulsion and paved the way for a whole new generation of propellantless spacecraft circling the globe and never running out of gas. But the ProSEDS, for which I was the project scientist, was canceled in the wake of the Columbia disaster and the next space tether propulsion experiment to fly was Japan’s T-Rex in 2010. To the best of my knowledge, there are no tether missions planned to fly anytime soon though there have been several proposed (EDDE and TEPCE are among them).