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posted by cmn32480 on Tuesday November 22 2016, @03:21PM   Printer-friendly
from the that-still-doesn't-mean-it-will-work dept.

After months of speculation and leaked documents, NASA's long-awaited EM Drive paper has finally been peer-reviewed and published [open, DOI: 10.2514/1.B36120] [DX]. And it shows that the 'impossible' propulsion system really does appear to work. The NASA Eagleworks Laboratory team even put forward a hypothesis for how the EM Drive could produce thrust – something that seems impossible according to our current understanding of the laws of physics.

In case you've missed the hype, the EM Drive, or Electromagnetic Drive, is a propulsion system first proposed by British inventor Roger Shawyer back in 1999. Instead of using heavy, inefficient rocket fuel, it bounces microwaves back and forth inside a cone-shaped metal cavity to generate thrust. According to Shawyer's calculations, the EM Drive could be so efficient that it could power us to Mars in just 70 days.

takyon: Some have previously dismissed EmDrive as a photon rocket. This is addressed in the paper along with other possible sources of error:

The eighth [error:] photon rocket force, RF leakage from test article generating a net force due to photon emission. The performance of a photon rocket is several orders of magnitude lower than the observed thrust. Further, as noted in the above discussion on RF interaction, all leaking fields are managed closely to result in a high quality RF resonance system. This is not a viable source of the observed thrust.

[...] The 1.2  mN/kW performance parameter is over two orders of magnitude higher than other forms of "zero-propellant" propulsion, such as light sails, laser propulsion, and photon rockets having thrust-to-power levels in the 3.33–6.67  μN/kW (or 0.0033–0.0067  mN/kW) range.

Previously: NASA Validates "Impossible" Space Drive's Thrust
"Reactionless" Thruster Tested Again, This Time in a Vacuum
Explanation may be on the way for the "Impossible" EmDrive
Finnish Physicist Says EmDrive Device Does Have an Exhaust
EmDrive Peer-Reviewed Paper Coming in December; Theseus Planning a Cannae Thruster Cubesat


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  • (Score: 2) by fubari on Tuesday November 22 2016, @06:09PM

    by fubari (4551) on Tuesday November 22 2016, @06:09PM (#431377)

    VLM, +1 for combining "liquid helium" and "LOL" in a single sentence. First time I recall seeing that :-)

    epic engineering challenge at liq He temps (LOL)

    What do you do for your day job?
    I follow the rough ideas of what you say, and am amazed you conceive of such things just because they seem like fun.
    Thank you for sharing (really!) :-)

    Now just out of curiosity, why liquid helium vs. liquid nitrogen super conductors?

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  • (Score: 4, Interesting) by VLM on Tuesday November 22 2016, @09:25PM

    by VLM (445) Subscriber Badge on Tuesday November 22 2016, @09:25PM (#431494)

    Because the liq N2 superconductors are all annoying ceramics that have to be shaped and fired and are brittle (last time I checked) but the liq He superconductors are just boring old metals. Weird metals, but still, just metals. There are some non-fun limits to current and magnetic fields for high temp conductors too.

    Whats not funny is liq He has very low heat of vaporization, you look at it funny and a liter boils off at like $10/liter. Its not like water where boiling takes like 600 degrees of heat or whatever it is exactly. So the idea of boiling off Liq He at 100 watts rate is kinda funny, someone has way too much money to be doing something like that...

    • (Score: 2) by Flyingmoose on Wednesday November 23 2016, @02:33AM

      by Flyingmoose (4369) <mooseNO@SPAMflyingmoose.com> on Wednesday November 23 2016, @02:33AM (#431624) Homepage

      But wouldn't the superconductor stop it from boiling? I mean MRI machines have huge amounts of current running through them...

      • (Score: 2, Interesting) by Scruffy Beard 2 on Wednesday November 23 2016, @06:29AM

        by Scruffy Beard 2 (6030) on Wednesday November 23 2016, @06:29AM (#431703)

        A neighbour was asking about a super-conducting flywheel one time (using electrons to store momentum).

        I found the super-conduction stops under high magnetic field strengths.

        Random wiki article [wikipedia.org]