US space agency NASA has validated a space drive that was previously thought "impossible". Now it confirms the microwave drive is a reality.

The EmDrive was developed by British scientist Roger Shawyer but was written off as impossible. Then a Chinese team went and built one too. Despite NASA rejecting the relativity-based drives as impossible, according to the law of conservation of momentum, it's now saying microwave thrusters appear to work.

Unlike traditional combustion that creates explosions of fuel to move, the EmDrive uses microwaves bounced around inside a closed container to create thrust. This means it can be installed on satellites to be powered by solar panels. Current satellites could be half the size at launch without the need to carry all the fuel they currently do.

The drive built by China managed 720mN, or 72g, of power. Not a great deal but enough to move a satellite about in space without the reliance on fuel.

The change of heart on NASA's part came after US scientist Guido Fetta built his own microwave thruster dubbed Cannae Drive. The results were presented on 30 July at the 50th Joint Propulsion Conference where they were deemed positive.

NASA said: "Test results indicate that the RF resonant cavity thruster design, which is unique as an electric propulsion device, is producing a force that is not attributable to any classical electromagnetic phenomenon and therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma."

With artificial leaves shown off this week and now fuel-free drives possible it's starting to look like deep space travel may soon become a reality.

READ: Man-made leaf could make deep space travel and off-world colonisation possible