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posted by janrinok on Friday August 01 2014, @08:49PM   Printer-friendly
from the it-shouldn't-work-but-does dept.

This story from a Wired article: NASA is a major player in space science, so when a team from the agency this week presents evidence that "impossible" microwave thrusters seem to work, something strange is definitely going on. Either the results are completely wrong, or Nasa has confirmed a major breakthrough in space propulsion.

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.

NASA states... "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"

 
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  • (Score: 3, Insightful) by wonkey_monkey on Friday August 01 2014, @09:52PM

    by wonkey_monkey (279) on Friday August 01 2014, @09:52PM (#76550) Homepage

    Two things are of note, as best as I have gathered as this story unfolds:

    Firstly, NASA tested two devices. One was the working device, the other was a device deliberately changed so as not to produce thrust. The problem is, they detected the same amount of thrust from both devices.

    Secondly, the test wasn't done in a vacuum. As I recall, there was a similar brief debacle when everyone was clamouring that lifters [wikipedia.org] were anti-gravity devices, because they'd been tested in a vacuum - the problem there was that the vacuum wasn't hard enough. Once you expelled all the air, they failed to function.

    This test wasn't even done in a partial vacuum, as I understand it.

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  • (Score: 3, Informative) by DrMag on Saturday August 02 2014, @03:11PM

    by DrMag (1860) on Saturday August 02 2014, @03:11PM (#76727)

    I have seen others offer a quote from the paper:

    After sealing the chamber, the test facility vacuum pumps are used to reduce the environmental pressure down as far as 5x10E-6 Torr. Two roughing pumps provide the vacuum required to lower the environment to approximately 10 Torr in less than 30 minutes. Then, two high-speed turbo pumps are used to complete the evacuation to 5x10E-6 Torr, which requires a few additional days.

    The full paper is here [aiaa.org], but I don't have access to it from where I am now. I'll have to verify the quote when I get back to work next week. I think the confusion is from the abstract [nasa.gov], which states that they did a test at ambient pressure, but says nothing about the other test configurations. I may certainly be wrong, but I doubt that a NASA team would fail to test this in vacuum before presenting like this.

    • (Score: 2) by DrMag on Monday August 04 2014, @02:19PM

      by DrMag (1860) on Monday August 04 2014, @02:19PM (#77213)

      Ok, now that I'm at work I've had a chance to read through the paper. The quote is valid, though to be fair it is in the description of the vacuum chamber capabilities, which is not necessarily the same as the setup used in the test. However, nothing in the paper suggests they did not, so either it's a gross omission, or they did tests at vacuum.

      In either case, they are planning a new design that they expect to be an order of magnitude better (0.1 N per kW), with an added feature to rule out another possibility I hadn't remembered to consider:

      The [new] tapered thruster has a mechanical design such that it will be able to hold
      pressure at 14.7 pounds per square inch (psi) inside of the thruster body while the thruster is tested at vacuum to
      preclude glow discharge within the thruster body while it is being operated at high power.