NASA confirms “impossible” drive

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Life imitates science fiction: NASA engineers have confirmed the functionality of an “impossible” space thruster drive.

British scientist Roger Shawyer has been trying to interest people in his EmDrive for some years through his company SPR Ltd. Shawyer claims the EmDrive converts electric power into thrust, without the need for any propellant by bouncing microwaves around in a closed container. He has built a number of demonstration systems, but critics reject his relativity-based theory and insist that, according to the law of conservation of momentum, it cannot work.

According to good scientific practice, an independent third party needed to replicate Shawyer’s results. As reported, this happened last year when a Chinese team built its own EmDrive and confirmed that it produced 720 mN (about 72 grams) of thrust, enough for a practical satellite thruster. Such a thruster could be powered by solar electricity, eliminating the need for the supply of propellant that occupies up to half the launch mass of many satellites. The Chinese work attracted little attention; it seems that nobody in the West believed in it.

However, a US scientist, Guido Fetta, has built his own propellant-less microwave thruster, and managed to persuade Nasa to test it out. The test results were presented on July 30 at the 50th Joint Propulsion Conference in Cleveland, Ohio. Astonishingly enough, they are positive.

Since no one understands the physics that are producing the thrust, it is wise at this point to be very skeptical of these results. A lot more testing and experimentation will be necessary before this can be made practical.

However, if it is what they think it is, it will make it possible to turn sunlight into thrust, meaning that spacecraft will no longer need fuel, and will be able to go places much faster using the constant thrust this drive will provide.



  • DK Williams

    You have an external input (solar energy), and an output (microwaves), so I don’t see a violation of the principle of conservation of momentum.

  • J Fincannon

    Photon rockets and solar sails are examples of propellant-less spacecraft. If your input is solar energy, it drops off with the inverse square of distance from the Sun, so it can’t be constant. If you carry something like a nuclear reactor or radioisotope power system, then you might get more or less constant thrust. The Pioneer anomaly explanation showed that even the humble thermal photon can slow you down.

  • Steve C

    Perhaps they can power it with cold fusion.

  • DK Williams

    True, would lose efficiency with increasing distance from the Sun; however, the craft should be have attained an acceptable velocity after leaving the inner solar system.

  • mivenho

    This could be a truly revolutionary discovery for space travel. And once it is verified by numerous other labs, and the the physics is nailed down, it could have many other applications besides thrusters.

  • Charles O

    Maybe dropping from the Earth’s orbit around the Sun to a nearer Sun orbit (just don’t burn up!) would give the greatest thrust … the potential energy from dropping into the Sun and coming back out would cancel BUT all the thrust from the collected solar energy would add to the spacecraft’s velocity!

  • Dick Eagleson

    Considering the teensy thrust measurements involved I’m inclined to think we have some kind of weak interaction between this electrified metal gadget and the Earth’s magnetic field going on. I’d be delighted to be wrong, but I don’t think this is going to pan out.

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