If you want to send something deep, deep into space, it’s impractical to load it up with lots of heavy propellant. Scientists with their eyes on long-distance space travel have contemplated thrusters that wouldn’t need any propellant at all. The EmDrive, a copper cone that would supposedly push forward on the vacuum…
Source: Gizmodo – The Supposedly Physics-Defying NASA Thruster Doesn’t Work, New Research Confirms