Once again the impossible drive is in the forefront of public news.
But thus far, I am still unimpressed. NASA seems to have thrown a lot of resources, to test the viability of the EmDrive. But I am not sure we are any closer to knowing if it "works".
Why don't we build a cube sat, launch it into orbit and try and push it out to Pluto?
Seems like we would get much more useful data much quicker.
EmDrive takes ~300W. You won't get it from a cubesat. You need over a meter of solar panels, or good 56kg of RTG battery.
It's been tested on Earth, made with materials and electronics meant to work in Earth ambient conditions: temperature, pressure, radiation. Putting things in space is not as simple as loading them onto a rocket. If they are to work, they need
...and funds. How many thousands dollars per kilogram? And this thing won't be a cubesat. It will be something of order of tons.
And for what? If it doesn't work, we won't know if it doesn't due to some failure or because it's a faulty concept. Let's first make sure we have something we can send into space.
We might, it depends on the scale of the project, and if someone proposed a proof of concept mission and is ready to finance it.
For a small scale technology demonstration mission such as the ones regularly performed aboard the ISS, it could be, for example, proposed through CASIS as a Physical and Materials Science R&D project, but it likely won't win any government sponsored grants (competition is fierce).
As for NASA, it depends to what TRL (Technology Readiness Level) can you qualify it. For a full-scale system component, it is currently only at TRL2 and lacks breadboard tests for independent verification and validation (IV&V) of the technology (TRL3), full-scale experiments (TRL4), and validation in representative environment (TRL5), before it can move to prototype demonstration in relevant environment (TRL6) and beyond.
NASA Eagleworks, in the most recent related paper that NTRS will return, in section V. Application of Technology to Space Exploration Missions, interestingly avoids description of small-scale technology demonstration missions and jumps right to potential full-scale application of the technology with a couple of interplanetary mission examples (to Mars and Titan/Enceladus at Saturn). Those serve as demonstration that what currently stands on paper (and has yet to be independently verified) has potential real-world applications, but that's it. Paper's summary clearly states that:
The near term objective is to complete a Q-thruster breadboard test article that is capable of being shipped to other locations which possess the ability to measure low thrust for independent verification and validation (IV&V) of the technology. The current plan is to support an IV&V test campaign at the Glenn Research Center (GRC) using their low thrust torsion pendulum followed by a repeat campaign at the Jet Propulsion Laboratory (JPL) using their low thrust torsion pendulum. The Johns Hopkins University Applied Physics Laboratory has also expressed an interest in performing a Cavendish Balance style test with the IV&V shipset.
The real information, not the "public news", is what NASA uses. Spinning a mundane negative result into hype, or describing the taking of measurements near the noise level of the instruments and then claiming it's a profound and confusing result, does not fool or impress the real engineers.
It does not work.
There is no reason to suppose anything fishy is going on.
Popular-press articles that claim otherwise, and articles written by the cranks themselves, don't change the actual facts even if they create a public mythology.
Now would a similar measurement in space help? A characteristic article I recall described small force measurements seemingly at random including those in the wrong direction or when the machine was off. Tiny effects in the environment and noise in the instruments swamp any real reading. If you tried it in a free orbiting platform, you would also get random changes due to variable atmospheric drag, solar particles, magnetic fields, outgassing of parts, differential cooling, and light pressure, not to mention peturbations from other satellites and bodies in the solar system and irregularities in the Earth (for a good description read up on Gravity Probe B and the drag-free orbit effect). Taking data, whether by careful positioning information or on-board accelerometers, you would have random changes that cannot be controlled for, exactly like the previous bench tests.
And you will still have reports that acceleration during the "control" phase (turned off) or in the wrong direction is somehow mysterious and suggestive, when it actually means that the trial run cannot be distinguished from the control and supports the "does nothing" hypothesis to enough sigmas to rule out any interesting effects.
I was just researching this now.
A working design basically doesn't exist yet, so it's still a question of "send what up?" All the major initial results are far more likely the result of thermal currents, which is obviously the case. Since then, the measurements have mostly been within the range of error.
There still appears to be promise, but they're still working on test sensitivity and drive design until they get some results that aren't probably the result of electronic noise.
Also apparently a bunch of electronics that work on earth don't work on space. Who knew?!
Why don't we build a cube sat, launch it into orbit and try and push it out to Pluto? Seems like we would get much more useful data much quicker
Well, ignoring the details of low earth orbit, lack of space for power and problems of monitoring a small dark object over vast distance ...
To traverse 7.5 billion kilometers starting at 0 m/s and using an accelleration of 50 micronewtons on a 1Kg cubesat means you would get your data in about 38 years. That doesn't seem very fast.
NASA doesn't work like that. It might be quicker, but it's also a lot riskier, and it has very little value. A Cubesat can't carry much instrumentation, so after flying it we'd be no closer to understanding how and why the EM drive works, which is the more important question at the moment.
And in 2018 we found out that the EmDrive doesn't work, without ever having to take it off Earth.
Tests on Earth have some big advantages over tests in space. On Earth, we can easily examine and modify the test system, to progressively rule out errors. We can progressively add more test equipment and e.g. shielding to refine the test.
If you launch an EmDrive on a small satellite, you get only one chance to build a test system. Any follow-ups with a changed test system would be very expensive as they would require another launch.
Paul March (if I remember well) explained that just to have Nasa GRC to accept working on EmDrive test, they needed to have reach a minimum thrust (50 or 100µN as I remember).
Getting straight to space with an untested device may lead to a fatal false negative. It happened that way with Cold Fusion, with two influential labs who failed , for reason that were unknown at that time, and because they made bad assumptions and refused to ask to experts (Nasa EW did similar error relative to Shawyer).
For me that false negative risk is a much more serious risk, thank the delay and the budget. If nasa can accept failure without dumping the idea , it is OK, but my perception is that it does not work that way.
