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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
(Score: 3, Interesting) by JoeMerchant on Tuesday November 22 2016, @05:47PM
To me, EM drive isn't about competing with solar sails, EM drive is about utilizing a plutonium pile vs a dark-side radiator plate to generate electricity for thrust. If you're "headed into the dark" and don't want to radiate heat against your acceleration, radiate to the sides instead.
Long ago, I heard a reasonable explanation of why the EM drive might not "break physics" having to do with relativistic properties of the microwaves changing in the chamber so that they struck one side and reflected at a different relativistic state (fraction of the speed of light) than the other side - so, from the wave's perspective it's bouncing back and forth equally, but from the chamber's perspective, it's hitting one side harder than the other.... Yes, this is oversimplified like explaining relativity with a rubber sheet and a bowling ball, but I think the world needs a NdGT level explanation of things like this to help people get their heads around it, instead of always presenting it as "breaking all known LAWS of Physics."
🌻🌻 [google.com]
(Score: 0) by Anonymous Coward on Tuesday November 22 2016, @06:47PM
Why not to the back? In the worst case, it has no non-negligible effect at all, and in the best case, it adds to your thrust.
(Score: 2) by JoeMerchant on Tuesday November 22 2016, @07:44PM
If you're headed "into the black" the back side would be solar heated, decreasing the efficiency of the radiator - lower temperature differential with the Plutonium pile means less useful energy captured.
🌻🌻 [google.com]