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There has now been a third positive study of the EM drive, and while I'm still skeptical, I'm starting to wonder if this is really possible. As such, I'm wondering what would be required to make this happen, specifically the following:

  • Mass
  • Size
  • Power
  • Thrust
  • Expense (Expensive materials, etc?)
  • Anything else worthy of notice?
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    $\begingroup$ Isn't it a teeeeeny-tiny bit too early to whip out slide rules? I'm as excited as you, BTW. $\endgroup$
    – Deer Hunter
    Jul 28, 2015 at 12:32
  • $\begingroup$ I know that getting the full information might be difficult, but getting some idea would be interesting. If it's a 1kg that requires little power, it might be worthwhile to try it in a Cubesat, for instance. It might just be interesting to see how it might be tested on orbit, if it's not ridiculously expensive. $\endgroup$
    – PearsonArtPhoto ♦
    Jul 28, 2015 at 12:55
  • $\begingroup$ It's a very exciting possibility. I would bet there's been some thinking at NASA over some beers and napkin-based calculations done, whether there's serious numbers which could be put together at this point is debatable. $\endgroup$
    – GdD
    Jul 28, 2015 at 13:16
  • $\begingroup$ Interesting. Maybe. I guess I'm an old curmudgeon. $\endgroup$
    – David Hammen
    Jul 28, 2015 at 16:51
  • $\begingroup$ I, too, am on the curmudgeon side of this issue. wired.com/2015/07/… $\endgroup$
    – Organic Marble
    Jul 28, 2015 at 20:11

2 Answers 2

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There is a great article by gizmodo, which gives an example of what would be required:

  • Power- 700W
  • Thrust- 88 uN
  • System Mass- 9 kG

To get 700W of power would require about 2 square meters of high efficiency solar panels, which is probably beyond most small satellites, but could still potentially be done. Where this could fairly easily be done is the International Space Station, however, the small thrust generated from this system would be difficult to distinguish from atmospheric drag.

The bottom line is, in order to make this work in space today, one would need a "mini" class satellite, probably one with ~100 kg. Those aren't exactly cheap, so I believe testing this on orbit would not be practical at this time, until further tests indicate that this does indeed work.

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  • $\begingroup$ If it would be difficult to distinguish from atmospheric drag that would be very useful indeed--keep the ISS up without having to bring up fuel. Unfortunately, my math comes out with it providing only 1% of the stationkeeping energy if powered by the whole ISS solar array. $\endgroup$
    – Loren Pechtel
    Jul 30, 2015 at 3:39
  • $\begingroup$ Is it even practical to generate 700W of power, plus the 9 kg mass of the engine system itself, without needing to add more than 88 uN of thrust in order to do anything useful? That is, will the thrust generated be greater by that required by the inertia of the mass of the additional power generating equipment (of whatever kind)? Maybe, but with those numbers, without having done the math, I'm skeptical... $\endgroup$
    – user
    Jul 30, 2015 at 11:15
  • $\begingroup$ There are plenty of systems out there that don't use thrust to maintain attitude. Reaction wheels and torque rods should be sufficient to maintain the attitude, no thrust needed. However, you'd need a decent sized satellite to have all of those systems, adding to the weight considerably. $\endgroup$
    – PearsonArtPhoto ♦
    Jul 30, 2015 at 12:06
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Unfortunately physics is physics, and magic is the most important requirement for an EM drive.

A recent experiment, this time with a much better test setup is disproving it

The explanation given for the small thrust observed is the earth magnetic field.

Note: This is still work in progress, but the conclusion seems inevitable.

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