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NASA's Impossible Propulsion EmDrive Is Heading to Space (popularmechanics.com)
An anonymous reader writes:The EmDrive, a hypothetical miracle propulsion system for outer space, has been sparking heated arguments for years. Now, Guido Fetta plans to settle the argument about reactionless space drives for once and for all by sending one into space to prove that it really generates thrust without exhaust. Even if mainstream scientists say this is impossible. Fetta is CEO of Cannae Inc, and inventor of the Cannae Drive. His creation is related to the EmDrive first demonstrated by British engineer Roger Shawyer in 2003. Both are closed systems filled with microwaves with no exhaust, yet which the inventors claim do produce thrust. There is no accepted theory of how this might work. Shawyer claims that relativistic effects produce different radiation pressures at the two ends of the drive, leading to a net force. Fetta pursues a similar idea involving Lorentz (electromagnetic) forces. NASA researchers have suggested that the drive is actually pushing against "quantum vacuum virtual plasma" of particles that shift in and out of existence. Most physicists believe these far-out systems cannot work and that their potential benefits, such as getting to Mars in ten weeks, are illusory. After all, the law of conservation of momentum says that a rocket cannot accelerate forward without some form of exhaust ejected backwards. Yet the drumbeat goes on. Just last month, Jose Rodal claimed on the NASA Spaceflight forum that a NASA paper, "Measurement of Impulsive Thrust from a Closed Radio Frequency Cavity in Vacuum" has finally been peer-reviewed and accepted for publication by the American Institute of Aeronautics and Astronautics, but this cannot be confirmed yet.
... or can ye?
The laws of physics have changed so much in the last few thousand years, why do we suddenly think we are at the pinnacle of dictating the laws that govern the universe just because we haven't found anything contrary in the last few hundred years? Our laws of physics are based around our extremely limited observation of a tiny portion of the universe; surely when more is observed then some of the laws are going to change.
Science relies on an open mind and proof of a theory by repeatable experimentation so all the naysayers who instantly dismiss anything with even the remotest possibility of redefining one of these laws of physics cannot be truly called scientists and are no better than those that would dismiss the notion of there being no god just as easily.
Does it count as an argument if I point out that the titular claim is full of hot air?
The guy behind the idea has (at least according to himself) formed a company with the stated goal of getting this thing into space. There's no scheduled launch in place yet, nor any specific plan. No mention of funding either, although a different guy is apparently launching a Kickstarter to get his own version into space. Don't worry, if it never goes I'm sure he'll spend the money wisely.
Right now it's all hand-waving, which means the concept is at pretty much the same place it's always been.
#DeleteChrome
That is why i said it needs to go on a little cruise.
Say. A lap up to and back from lunar orbit. A distance that is still both close enough to closely monitor the test article, and far enough that if it were using evaporated cavity materials as reaction mass, the entire test article would need to be consumed.
It is otherwise impossible to rule out what you suggest: it may well be happening, but that kind of issue would be insufficient to satisfy the reaction mass requirements of the proposed test. A successful completion wouldnt rule out vapor release, it wiuld just show it does not dominate the generated thrust. Until a result that can only happen if reactionless drive is produced, and in a big way like that, the argument that there is reaction mass, and that it dominates the recorded thrust will never die.
The press hype goes on despite results of two experimental results that clearly indicated the mythical drive to not thrust: A group of physicists at the university of Dresden measured miniscule thrust, but strangely enough the thrust went into the same direction when the "EMdrive" was rotated by 90. So they figured that what they measured was probably resulting from an interaction of the electric powering from the outside with the magnetic field of earth. They couldn't easily remove this probable source of error in their setup, but a chinese group of physicists managed to do so: They powered the "EM-drive" from a battery that was within the same enclosure - and voila - no more thrust to be measured.
Good thing it's not a rocket then.
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The issues are:
1) reported thrust is very small. So small that sources of experimental error will plague even immaculate setups on earth.
2) as prior poster mentioned, evaporating cavity materials forming and being vented currently can explain, at least hypothetically, the majority of the thrust, and experimental error bars can take the rest.
3) a test in space is likely to be a short mission with release and capture over a few meters of flight, if that. This is not sufficient to rule out outgassing.
4) the reaction mass requirements to send the device in a gravity assisted return mission are well known. (Thanks Apollo program!)
5) The difference in solar insolation at low earth orbit, and at lunar orbit are academic. A test device using solar power would not experience a significant change in power generation over that distance.
6) assuming the test device cannot generate more power than the solar array it is fitted with, and is composed of less mass than would be required to get to the moon and back at that level of energy production, then it can only succeed in that mission if the reaction less drive claims are true.
by putting it through a trial that it cannot be successful at without the claimed feature, we can then safely say it has that feature should it succeed.
Without hard elimination of other variables, which a small test will likely never satisfy satisfactorily, the drives claims cannot be rigorously tested.
Moon flyby will nail it big if it worked.
NASA's Impossible Propulsion EmDrive Is Heading to Space
It's not NASA's.
systemd is Roko's Basilisk.
Yes.
We care a lot. If something doesn't follow the laws of physics as we know them, that means that either we don't understand the something or there is something we don't understand about the laws of physics.
If we don't understand what is happening to something and we figure it out, that's useful engineering knowledge.
That's actually the less awesome potential. If we don't understand something about the laws of physics and we can figure that out instead... well that changes the world. It makes possible what we think impossible.
If an alien landed a spaceship in the middle of Times Square, it wouldn't necessarily change our understanding of physics. This could.
3) a test in space is likely to be a short mission with release and capture over a few meters of flight, if that. This is not sufficient to rule out outgassing.
I have discovered a little-known practice called "reading the article" that can help clarify what is proposed:
Fetta intends the satellite to stay on station for at least six months, rather than the six weeks that would be typical for a satellite this size at a altitude of 150 miles. The longer it stays in orbit, the more the satellite will show that it must be producing thrust without propellant.
I don't care if it's 90,000 hectares. That lake was not my doing.
The problem is the people crossing the line by insisting it's fake and so further testing must not be funded. Talk about self fulfilling.
A close second is those declaring the latest test flawed when they haven't even read the paper yet.
Skepticism is appropriate but that goes beyond.
What upsets me more is the fact that there's an argument at all.
What's wrong with sending it up to prove or disprove it?
I am so sick of the attitude of : It's my solution or no solution. Who cares if they are proven wrong and the thing works? Too many Effing ego's in the room.
~ People that think they are better than anyone else for any reason are the cause of all the strife in the world.
The difference is N Rays depended on the tried and true scientific principle of "oooooohhh..... I think I see it!"
The Emdrive is either producing thrust, or fooling each type of different method people have used to measure the expected effect. Everybody measures thrust. Either everybody is making the same mistake (which I admit is quite possible), or there is something actually occurring we just don't understand yet.
First off, if the engineers designing this thing are remotely competent there won't be any out-gassing.
Uncontrolled out-gassing is, and has since the beginning of the space age, been a really obvious problem. So it'll be designed from the get-go to avoid uncontrolled out-gassing.
It also doesn't have to be brought back to Earth to be weighed. Acceleration, if any occurs, can be measured pretty precisely. The degree of acceleration is a product of the mass and velocity of out-gassing.
If there is any observed acceleration you just have to wait until the amount of reaction mass necessary to account for that acceleration exceeds some reasonable amount and we're done - it works. No tour of the solar system necessary.
Minutus cantorum, minutus balorum, minutus carborata descendum pantorum.
a bowl of petunias and a very surprised looking whale....
i wonder if it will be friends with me? ...
- Douglass Adams RIP
I've been following emdrive for a while now. Prof McCulloch's book and emdrive paper provide the best description I have yet seen of an emdrive. As mentioned above there are no 'laws' of physics, just a collection of theories which seem to describe observed facts well. The theories change or are expanded to suit fresh observations. The best theories can be used to make predictions and provide explanations in disparate other problematic observations and this is the case with Prof McCulloch's work.
If NASA are prepared to use resources to send one of these things to orbit then the case for emdrive is at least still open. Speaking personally, I would like to use a 3d printer to build a 10x10x10 Cu block of these cavities, that should give a definitive answer. How about it Mr Musk?
Problems always arise on the edge of physics from the difficulties of making measurements. That's the fun of the thing...