China Claims Tests of 'Reactionless' EM Drive Were Successful (popsci.com)

An anonymous reader quotes a report from Popular Science: The "reactionless" Electromagnetic Drive, or EmDrive for short, is an engine propelled solely by electromagnetic radiation confined in a microwave cavity. Such an engine would violate the law of conservation of momentum by generating mechanical action without exchanging matter. But since 2010, both the United States and China have been pouring serious resources into these seemingly impossible engines. And now China claims its made a key breakthrough. Dr. Chen Yue, Director of Commercial Satellite Technology for the China Academy of Space Technology (CAST) announced on December 10, 2016 that not only has China successfully tested EmDrives technology in its laboratories, but that a proof-of-concept is currently undergoing zero-g testing in orbit (according to the International Business Times, this test is taking place on the Tiangong 2 space station). If China is able to install EmDrives on its satellites for orbital maneuvering and altitude control, they would become cheaper and longer lasting. Li Feng, lead CAST designer for commercial satellites, states that the current EmDrive has only a thrust of single digit millinewtons, for orbital adjustment; a medium sized satellite needs 0.1-1 Newtons. A functional EmDrive would also open up new possibilities for long range Chinese interplanetary probes beyond the Asteroid belt, as well freeing up the mass taken up by fuel in manned spacecraft for other supplies and equipment to build lunar and Martian bases. On the military side of things, EmDrives could also be used to create stealthier, longer lasting Chinese surveillance satellites.

Comments

Re:so is there a good theory?

[Anonymous Coward]

I know ethan is not loved here anymore, but: https://medium.com/starts-with...

Re:Hilarious

[arth1]

Or maybe Newton's 3rd law isn't true in some circumstances. Now that would be exciting.

We already know it isn't always true. The Lorentz Force happily violates Newton III. And so does quantum mechanics.

Re:Misleading

[Theaetetus]

This is not an EmDrive. It's a drive of the same type as an EmDrive, resonant cavity thrusters, but EmDrive is a trade mark for one particular variant by Satellite Propulsion Research Ltd, which this isn't.

First, it's a drive, yes? And it's using electromagnetism, yes? Therefore, it's at best merely descriptive, and therefore not a protectable trademark.
Second, the ElectroMotive Designs company already has a registration on the EMDRIVE mark for converting cars and trucks to hybrids. So, Satellite Propulsion Research can go suck on the smaller end of a resonant cavity.

Re:so is there a good theory?

[coastwalker]

Because his musings are now generally only available on Forbes which is not accessible if you run ad blocking software. The link above is on another site though.

Re:Hilarious

[serviscope_minor]

We already know it isn't always true. The Lorentz Force happily violates Newton III. And so does quantum mechanics.

Yeah, no. Also, well done for providing a link to an article which doesn't remotely back up your claims.

BULLSHIT

[110010001000]

More fake news. Go to CAST website. THERE IS NOTHING THERE ABOUT IT. And the website is in English too. Stop posting this bullshit about the EmDrive. It is this decades eCat.

Re:BULLSHIT

[l0n3s0m3phr34k]

I'm pretty sure I remember you have previous posts calling people "space nutters", and are pretty rabid in attacking anything outside mainstream NASA. The claim that CAST has nothing just because the English version has nothing means nothing...unless you've gone through the Chinese language version and can prove the two sites contain the same information.

I found another reference in English at http://spaceflight101.com/shijian-17-rendezvous-with-chinasat-5a/: "and debuting a Hall-Effect Thruster system for use on future Chinese GEO satellites"

Digging into this via Google Translate does provide far more information. The information your claiming doesn't exist actually DOES exist, on the stdaily.com article. It's just all in Chinese, so you have to put some effort in to translate it. My link is at translate.google.com and https://translate.googleusercontent.com/translate_c?depth=1&hl=en&rurl=translate.google.com&sl=auto&tl=en&u=http://digitalpaper.stdaily.com/http_www.kjrb.com/kjrb/html/2016-12/11/content_357005.htm%3Fdiv%3D-1&usg=ALkJrhhkYPDNKL_9BxSu6OAkt5KIHsse9Q but I don't know if this link will work for anyone else.

Using Google page translation:

Chen Yue said: "We use the classic electromagnetics and electrodynamics to design several different shapes of thrusters, theoretical analysis can generate thrust thrust, and through the test of the thrust, the results in line with theoretical analysis. Science and Technology Daily Beijing December 10 " Roger Xiaoe in an interview was also asked this "eternal" problem, he made it clear that the EM engine does not violate Newton's law of mechanics: "EM engine in a direction to generate propulsion, if circumstances permit, will In another direction, the momentum of the whole process is conserved. "This explanation is considered ambiguous.

"We have successfully developed several specifications of several prototype principle, the establishment of experimental verification platform to complete the milli-level micro thrust measurement test, through several years of repeated tests and the corresponding interference factor investigation test, confirm that the type of thruster Thrust exists. "Chen Yue introduced that they have completed the test device can be used for flight test development, is in orbit verification.

"This technology is currently in the latter stages of the proof-of-principle phase, with the goal of making the technology available in satellite engineering as quickly as possible," said Li Feng, chief architect of the China National Space Technology Institute's communications satellite division. , The principle prototype volume, thrust is small, require special engineering methods, optimize the cavity design, improve the cavity quality factor, reduce the loss, the microwave energy is more effective for generating thrust. At present, the thrust is measured to micro-cow level to millennial level, at least to improve the level of 100 cents or even cattle-level satellite can be used for attitude control, orbit and so on.

Re:so is there a good theory?

[guruevi]

It hasn't been successful at all. The only tests seem to describe micronewtons of force in exchange for ~100Wh of energy consumed, a far cry from the flying car engine it's creators promised. The micronewtons aren't enough to go up against earth or sun gravity so useless to propel anything anywhere and the energy source would have to be massive.

Most of those test seem to be also both in the range of error and the results have very low confidence by the researchers themselves, if there were anything useful, you'd be sure as hell this would already be up to being tested in space. There were some hyped up news stories about this drive but nothing useful so far.

Re:so is there a good theory?

[silentcoder]

Because there is a lot more to cosmology than gravity and movement. There are several theories to explain the movement of the galaxies - some of which do essentially come down to gravity behaving differently in some situations (like over very long distances).

So when you have more than one explanation for an observation - how do you choose one ? Well you do some more maths - and figure out what ELSE would be observable if the theories are true - and then see if any of those things can be observed. All of the theories make a number of these "predictions" and they all turn out false.
Dark Matter's predictions have all turned out to be true. Predictions way beyond the speed at which galaxies rotate. The presence of that mass, and where it is concentrated, would affect other things - and those things we can look for, and we've found them. And gravity bends light, so if there's a huge clump of unobservable matter somewhere, it would bend light -and we should be able to see that the light was bent (we've known how to observe graviational lensing since Einstein's days). Again we can see distinct patterns of graviational lensing that fit the predictions of dark matter theory and goes against what is predicted by every competing theory.

Now it's possible that along the way we'll come up with a different theory that explains observations better - but some of the smartest people in the world are trying and of all the ideas they've had none has matched the observations better, none have made predictions that better fit the other things we can observe. Right now, dark matter is by far the single strongest theory we have for explaining the way galaxies move - and the only one where the other things you can predict would be true is ALSO being observed. It's an extremely strong theory backed up by a lot of solid observations.

There are also active experiments to try and find a way to detect dark matter - partly this is made difficult since we're not sure what to look for, some people think it's made of very large, heavy particles and others that it is made up of tiny particles (but lots more of them) called "Axions". The idea that the EM drive may be using dark matter for fuel is based on the Axion idea.
But since we don't know - and have no real way of theoretically saying one is more likely than the other - we are looking for both. Doing all sorts of complex experiments to try and create conditions where - if dark matter is present we can force it to interact with something else and reveal itself. We haven't succeeded yet, but considering how difficult it is to look - we aren't giving up yet either.

Re:so is there a good theory?

[Ol Olsoc]

I haven't googled it, but I've always wondered why physicists are so certain that dark matter is a thing

Dark matter is a placeholder. It isn't necessarily dark, nor matter, or even a thing. Its more of "We're not certain exactly why some aspect of the universe isn't what we think it should be.

So you could declare everything wrong, and go back to the caves, or put in a placeholder so you can do further research and eventually figure out what the placeholder "dark matter" is.