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Space China Technology

China's Radical New Space Drive 419

Posted by samzenpus
from the learning-to-fly dept.
First time accepted submitter Noctis-Kaban writes "Scientists in China have built and tested a radical new space drive. Although the thrust it produces may not be enough to lift your mobile phone, it looks like it could radically change the satellite industry. Satellites are just the start: with superconducting components, this technology could generate the thrust to drive everything from deep space probes to flying cars. And it all started with a British engineer whose invention was ignored and ridiculed in his home country."
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China's Radical New Space Drive

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  • by fyngyrz (762201) on Thursday February 07, 2013 @11:12PM (#42828495) Homepage Journal

    chances are any thrust developed is actually air that's getting heated up and expanding out of the container.

    That effect would not last long. If it produces continuous low thrust in atmosphere, that can't be it.

    More likely, as one of the groups that looked at this observed, is that all that RF (2kw) is simply interfering with the instrumentation.

  • by Anonymous Coward on Thursday February 07, 2013 @11:17PM (#42828529)

    FTFA:

    > Shawyer continued to produce and test more advanced demonstrators, working out elaborate ways of ensuring that the test results are valid and not the result of air currents, friction, ionization, interference or electromagnetic effects.

  • by Dan East (318230) on Thursday February 07, 2013 @11:19PM (#42828539) Homepage Journal

    Some rather talented scientists evaluated this first hand:

    Boeing's Phantom Works, which works on various classified projects and has been involved in space research, went as far as acquiring and testing the EmDrive, but say they are no longer working with Shawyer.

    I'm sure if the drive was useful in any meaningful way it would have been utilized. So this does not bode well for the practicality of the drive for real-world applications.

  • Mach-Woodward Effect (Score:3, Informative)

    by sanman2 (928866) on Thursday February 07, 2013 @11:41PM (#42828679)

    Well, that's what people have said about the Mach-Woodward experiments, but an opposed piston design is now being tried out to isolate any noise-producing effects for remediation:

    http://arxiv.org/abs/1301.6178 [arxiv.org]

  • by DerekLyons (302214) <fairwater&gmail,com> on Thursday February 07, 2013 @11:47PM (#42828711) Homepage

    From TFA: Propellant can account for as much as half the launch weight of a geostationary satellite. This means that, in principle, fitting one with an EmDrive rather than a conventional drive, could halve launch costs.
     
    That depends entirely on the power system needed to operate the drive. That's the real Achilles heel of various non chemical propulsion systems - they eat a lot of juice and the resulting power supplies negate most (if not all and then some) of the savings of not carrying conventional fuel.

  • by Andy Prough (2730467) on Friday February 08, 2013 @12:22AM (#42828865)
    The FAQ deals with conservation of momentum, allowance for bouyancy, electromagnetic effects, convection and other issues here: http://emdrive.com/faq.html [emdrive.com]. A fantastic picture of the device on this page: http://emdrive.com/ [emdrive.com].

    Here are some of the FAQ answers:
    Q. Why does the EmDrive not contravene the conservation of momentum when it operates in free space?
    A. The EmDrive cannot violate the conservation of momentum. The electromagnetic wave momentum is built up in the resonating cavity, and is transferred to the end walls upon reflection. The momentum gained by the EmDrive plus the momentum lost by the electromagnetic wave equals zero. The direction and acceleration that is measured, when the EmDrive is tested on a dynamic test rig, comply with Newtons laws and confirm that the law of conservation of momentum is satisfied.

    Q. Are there any convection currents which might affect the results?
    A. Convection currents did not affect the results, as measurements were taken with the thrust vector up, down and horizontal. Test runs were also carried out using a thermal simulation heater to quantify the effects of change of coolant temperature.

    Q. Have electromagnetic effects been taken into account? These include interactions between current-carrying conductors and between such conductors carrying RF currents and nearby metallic structures in which currents might be induced.
    A. Stray electromagnetic effects were eliminated by using different test rigs, by testing two thrusters with very different mounting structures, and by changing the orientation by 90 degrees to eliminate the Earth’s magnetic field.
  • by ilicas (2799301) on Friday February 08, 2013 @12:34AM (#42828927)

    ... , and the original builder and designer never tested it in a vacuum chamber.

    maybe try reading the context of a post before inserting the snark next time?

  • by jmauro (32523) on Friday February 08, 2013 @01:00AM (#42829017)

    Ford wanted to use the Robinson since it was shown to be a better screw for mass production, but couldn't come to an agreement with him to license the screws in order to allow them to be made in sufficient quantity for Ford's manufacturing use.

    So Ford moved on to another screw type.

  • by j-beda (85386) on Friday February 08, 2013 @01:09AM (#42829053) Homepage

    experiment (since IANAP), I do want to say that there seems to be a troubling trend amongst the best and the brightest in many STEM fields to mistake theory for reality. Theory is great and proceeds under the scientific method from empirical observation, but as we've seen throughout history, new phenomena and corner cases to arise and require theory to be amended.

    While it is certainly worthwhile to keep an open mind and question our assumptions, there are a variety of different levels of confidence we have in different ideas. The major conservation laws (linear momentum, energy, angular momentum) are mathematically equivalent (via Noether's theorem) to symmetries of the space. If the laws of motion are independent of position then linear momentum is conserved. If linear momentum is not conserved, than the laws of motion are not independent of position. (similarly for rotation invariance angular momentum conservation and time invariance conservation of energy).

    http://en.wikipedia.org/wiki/Noether's_theorem [wikipedia.org]

    So this goes way beyond understanding of EM theory - if we have a case where momentum is not conserved, that will fundamentally change how we think the universe is put together. In my mind it is much much much more likely that there is error or fraud or psychosis than momentum is not being conserved.

  • by Bob Hearn (61879) on Friday February 08, 2013 @01:46AM (#42829217) Homepage

    ... sort of. And it is established physics. See Swimming in Spacetime: Motion by Cyclic Changes in Body Shape [mit.edu], Science, 2/27/2003, by Jack Wisdom.

    But this mechanism relies on general relativistic effects, and only works in curved spacetime. Momentum conservation is not violated, because while the location of the object changes, its momentum (thus velocity) does not -- it simply cyclicly translates itself through space.

    My first thought reading about the EmDrive was that Shaywer had found a way to reproduce this effect using a microwave cavity. But unless I'm mistaken, this does not appear to be the case, and I don't follow the arguments that Shaywer's drive should work.

  • Re:Skepticism (Score:5, Informative)

    by causality (777677) on Friday February 08, 2013 @03:42AM (#42829719)

    Sorry, no. The whole point of skepticism is to assign a negative (false) value to anything but proven assertions.

    That's a related concept properly called positivism.

  • by Anonymous Coward on Friday February 08, 2013 @07:00AM (#42830521)
    Congratulations! Thanks to guys like you, in a few years China will dominate the space while you and your peers will continue planting with yours hands and burning witches on Saturdays.

    PS: Electromagnetic waves can serve as "reaction mass", see the case of the Pioneer spacecraft and the electromagnetic radiation emitted by it you know popularly as "heat".
  • by Anonymous Coward on Friday February 08, 2013 @10:10AM (#42831525)

    "The momentum gained by the EmDrive plus the momentum lost by the electromagnetic wave equals zero."

    The momentum of a photon is determined by its frequency, with p = hf/c.

    If the microwave photons were transferring momentum to the drive they would change in frequency. This is (a) easily detected, and (b) in contradiction to the high Q values claimed for the device. If the frequency of the microwaves is changing, they would not continue to resonate, if it is not, they are not the changing in momentum.

    From TFA, "Shawyer says that the Q value, and hence thrust, can be boosted by a factor of several thousand -- producing perhaps a tonne of thrust per kilowatt of power." The more momentum his drive "extracts" from the microwaves, the larger the change in frequency, the lower the attainable Q. Shawyer is contradicting his own FAQ.

  • by Pinky's Brain (1158667) on Friday February 08, 2013 @12:19PM (#42833157)

    EM can serve as reaction mass, but it creates very little momentum.

    This shows the problem :

    http://en.wikipedia.org/wiki/Nuclear_photonic_rocket [wikipedia.org]

    PS. with antimatter/matter fuel a photonic drive would make sense.

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