Daily Galaxy and Physics-Astronomy are talking again about a September 2017 video that has an english title that says China is testing the controversial EMDrive in space. The video talks about China putting up a communication satellite. The English language title talks about EMdrive being tested and propellentless propulsion. EMdrive is a claimed propellentless propulsion system. One of the researchers in the video is Dr. Yue Chen who did make a claim about a successful lab test of an EMdrive system in 2016.
EMDrive is a truncated cone-shaped copper structure which reflects microwaves many times. The cone shape could also be made from superconductors. The claim is this object generates propulsive force without using any propellent.
However, as Nextbigfuture reported in 2017, the actual video does not make that claim. Listening to the Chinese that is spoken, we find the details of the EMdrive are NOT discussed. They do NOT ANY CLAIMS of having proven the controversial physics. The english language title is misleading and does not represent what is in the video. The video is mainly chinese propoganda that they have world-class regular communication satellite technology.
There is a brief section where Yue Chen discuss that they have done tests of propellentless electromagnetic propulsion but they do not discuss any new space-based tests.
They discuss 2000 kilogram payload and 120 transponder channels.
In December 2016, Yue Chen told a reporter at China’s Science and Technology Daily that his team was testing an EmDrive in orbit, and that they had been funding research in the area for five years. Chen noted that their prototype’s thrust was at the “micronewton to millinewton level”, which would have to be scaled up to at least 100–1000 millinewtons for a chance of conclusive experimental results. Despite this, he said his goal was to complete validation of the drive, and then to make such technology available in the field of satellite engineering “as quickly as possible”.
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No, the biggest obstacle is that it doesn’t exist.
The thrust level is not useful for a continuous thrust Martian transfer. The biggest obstacle to a space based test is building a space rated demonstrator.
This is definitely an approach that is being examined.
Even on this very site there was recently a proposal. Google “Zubrin Dipole drive”
Simple physics shows the limits of photonics propulsion. This and Einstein’s simple equation of E=mc2 shows that the mass/ pressure generated in the Bell is limited by energy input. To generat even 1newton of acceleration it would take megawatts of power.
Fwiw this is simply an electromagnetic effect of compressed and accelerated photons in a confined region causing an extremely small swelling of space time in the Bell causing a pressure gradient with surrounding spacetime. There is promise there but not with materials and energies we wield now
You are calculating with a fictional test article then?
The Chen prototype had ~three orders of magnitude lower thrust. Mass unknown? With the prototype, one would have to thrust for a few months for 1- 2 m/s delta-v and then external forces will be harder to filter out. As the article hints and as you calculated, 0.1 N is a good level to prove the concept beyond doubt without many complications.
I was perhaps thinking of existing test articles and if using space testing would accelerate the work. If thrust could be proven, funding would probably be huge in short order.
Current prototypes would have to thrust for a long time pointing in the same direction. This means chemical thrusters or reaction wheels on the test article. I googled a bit on orbital decay and it looks like GEO is useful but needs about 45 m/s delta-v per year in orbital keeping to compensate for perturbations.
Well…..I hope the EM Drive works; I can’t believe the Chinese would launch without having confirmed its capabilities.
Is there anyone on this string who remembers the excitement around the Dean Spacedrive System? https://en.wikipedia.org/wiki/Dean_drive
Thank you — for reading some of my related comments — its nice to know that i’m not “writing into a vacuum”. (2) I didn’t really mean to give criticism to your advantage/drawback questions.
I was indirectly expressing deep frustration with the 6 or 7 order-of-magnitude difference between the supposed best-of-show (terrestrial), and the super-conducting magnificence that is inevitably trotted forth for visions of The Future that are right out of a 1950s Amazing Stories SciFi pulp magazine.
I was also thwarted (1500 character limit now) in furthering the math point.
a = 0.0004 m/s² × (60² ⋅ 60²)
a = 5,184 m/hr² or…
a = 5.2 km/hr, for each hour under acceleration.
Dunno about you, but 5.2 km/hr is pretty definitive. It may not sound like much, but 3 MPH (or thereabouts) is like a fast bloke walking. You’re not likely to confuse that for some other imperfect-test-environment cause.
Moreover, “std science” would be to send up 2 of them, point in different directions, (90° orthogonal?) and let ’em roll. Or … maybe … send one up, point it Celestial North, run for an hour, then West, run for an hour, South, and then East.
I know you don’t come back to the starting spot, but at least the thing would relatively speaking ‘stop’.
GoatGuy
Most hydrogen is neutral, and uninterested in magnetic fields.
And with something like one atom per cubic meter, that’s not much to grab on to…
I have high hopes for what he does too, but I wouldn’t make that my standard of reality…
Well guys my moneys(literally) is on Elon Musk. He is much better informed than all of us put together. If he is not interested in EM drive technology then I am betting there is nothing to it.
There is so much hydrogen in space why don’t use the free hydrogen that has been expelled by the sun? A magnetic field would attract the hydrogen from the front and expell it out the back. No fuel just field.
I just tried to verify my email address associated with my account, by clicking the link sent to me by email, but the page is not working.
It would be surprising if SpaceX has not at least considered building their own EM drive for testing. It could use the power systems of a Falcon upper stage. I don’t think the upper stage has PV panels, so you’d need to add those, perhaps some heavier duty power electronics, and wiring, the frustum of course, one, or more magnetrons, or a RF power supply, and an antenna, accelerimeters, and/or laser reflectors.
The second stage is wasted anyway, and their must be some satellite launches that have enough spare payload to place the hundred, or so kilograms of extra mass needed to test the drive in orbit. The risk would be small, since the second stage in orbit is free, but the payoff is tremendous, even if it just kills off a worthless path of research. If it turned out to work, the result would be more disruptive than all Musk’s ventures put together.
I don’t see how Elon could resist it!
If you follow the endless discussions in the NASA Spaceflight forum about these topics, you surely have noticed that the presumed phenomena are close to the threshold of detectability even for torsion pendulums, have a lot of potential noise sources (handling high voltage/heat/EM waves), while having a strong entry barrier for mainstream acceptance.
Given they all can’t exist unless a lot of physics is overturned or deeply reformed, having a gnat’s fart levels of thrust won’t impress the skeptics.
These require something more in terms of believability.
Torsion pendulums are fine on Earth for testing this. If anything it works well because you can test for a moment, then play with the device. There is a bit of a difference between a test rig in a vacuum chamber and an actual independently powered satellite.
I have been following the EM-drive articles and your subsequent math grounded reality checks over the years. I’m well aware of the issues. My post was merely questions about the advantages and/or drawbacks of performing verification in space. The thrust effects seem to be so small that ground tests are inconclusive. Will it be any better in space? Space is far from a pristine lab environment in the inner solar system.
I did a comment and it disappeared. It was a long one, no links nor improper language.
Is this a policy of the new board, to avoid having users posting too often?
Following this whole affair, it seems if falls either on the “doesn’t work” or “it’s really weak” kind of phenomena.
What I find curious is the multiplication of such reports and proposals, with different sources and kinds of devices (Woodward’s METs, Emdrives, now symmetric capacitors, McCulloch’s LEMdrive, etc).
Looks to me like the start of another cold fusion/LENR affair, where there are several ideas and reports of measurable phenomena, but they are hard to control or replicate due to poor understanding of what’s going on. Because sorry, it should be clear by now LENR is real, by force of the many repetitions and positive results across the years from different sources, we simply don’t know what’s really going on or how to control it.
But in this case, we could be facing a mass self delusion, of people weary of waiting for the retrofuturistic dreams of yore to arrive (the allure of space and interstellar travel), or a revolt against “mainstream physics” where group compliance and peer acknowledgement have become more important than results.
In any case, the barbarians are at the gates, and the anomalies start piling up, clamoring for validation and a potential revolution
Given the peak of interest in weak but enticing “propellantless” (really reactionless) thrusters of late, there will come a day when they need to be placed in space and tested. Eppur si muove still is a very convincing argument, specially in the vacuum of space and far from other local forces and perturbations.
And the presumed cheapening of space access we can expect to see in the next decades will certainly help test these presumed devices.
If sending your dingy new physics apparatus into orbit costs less than the budget of a whole NASA department, more universities and companies will be willing and able to test their contraptions where they should.
This is another potential revolution coming from cheap space access: test phenomena at the edge of detectability on Earth, or that depend on the special conditions of space to manifest themselves.
Ever watch videos of “perpetual motion machines” (which infest youtube)? Oh, there are thousands. And dozens of “breakthrough” ideas, almost all relying on magnetics of one form or another.
What I always note is that the “breakthrough” device is always so close to “over unity” that it takes a big push of energy to get it started, then supposedly just keeps turning against air friction … indefinitely.
The ordinary bloke or lass is completely unaware that there is a mountain of difference between “turning for a long time on great ball bearings” and “doing appreciable work at that rotational rate”. Huge difference. 3 or more orders of magnitude.
I see the same in your very reasonable outline of potential issues. Testing an apparatus which has been widely and loudly billed as having meganewtons per megawatt (LOL) potential, the ability to jet between Earth and Jup in less than 6 months, and so on, requires output thrust 6+ orders of magnitude (1,000,000x) over dainty little in-space experiments which might charitably cough up millinewtons per kilowatt.
Don’t get The Goat wrong: he would definitely be interested in seeing even a single, solid, non-controversial free-standing-machine demonstration yielding 100 millinewtons from a kilowatt of injected energy. For an hour. (i.e. something that a solid bunch of lithium batteries might provide.)
F = ma
a = F/m … where (F = 0.1 N, m = 250 kg)
a = 0.0004 m/s² … times 60²
a = 1.44 m/min² … times 60²
GG
I’ll throw some questions out in the air…
What are the obstacles in building an EM drive test article for space?
I guess these fall into two or three categories. Components that must survive launch and operations in space. Guidance and control systems. Money, size and weight…
Is it really any better testing in space?
The motivation seems to be to eliminate other potential sources of thrust by running the test for very long to see accumulated kinetic energy beyond what can be explained by those sources. However, in space there will be other factors like radiation pressure, drag, magnetic fields, plasma interactions etc. Thrust is very small so the mass of the test article can’t be big.
Where is the best place to run a space test?
LEO may have too much aerodynamic drag? Far away from earth is expensive. Maybe put it in GEO on the shadow side of earth to minimize solar interactions? Then we have a power problem and we cant use solar cells. So the test article needs an RTG.
Maybe it’s wrong thinking about a probe accelerating away. Maybe the design should be a spinning test article instead. Then it can be shielded in LEO and spinning mass can be low. Power infrastructure can perhaps be external to the spinning thing. Why can’t we build this on Earth?