NASA's Investigation Into EM Drives - What if?

The real question here is whether or not the Quantum Vacuum is producing enough electron-positron virtual pairs to result in acceleration of these pairs to produce the measured force. It is my understanding the microwave fields (E-M) would circulate the pairs in opposing directions, right? Then there is also the consideration of dark matter (we seem to not have much of a clue about its properties), but suppose that it somehow does not produce pressure as gas molecules do, but is more of a membrane like material - does this mean it rebounds after the acceleration? OR does it stay stretched? I expect this will be a steep learning curve for us all.

How is the conservation of momentum applied to the following?

A long electromagnet is fixed on a table top. It is in a demagnetized state.

A short cylindrical permanent magnet is placed near the fixed magnet aligned in such a manner so that when the electromagnet is energized it will be in repulsion.

The electromagnet is then energized.

The permanent magnet will begin to roll away from the fixed magnet.

How does the conservation of momentum apply here?

The needle of a small magnetic compass is mechanically forced into the opposite direction. It is then released. The needle is accelerated by earths magnetic field as it begins to align to the equilibrium position.

How does the conservation of momentum apply here?

What if there were some way to use the dipolar field of the Sun and planets as reaction fields?

http://cr4.globalspec.com/thread/11752

F=ma

∫F·dt = ∫m dv/dt ·dt = ∫p, thus momentum is conserved through the action of a time-dependent impulse that is either changing or is contant then removed from action (by a switch).

Conservation of momentum as applies to this situation I think requires that for any force to act upon an object in an inertial frame, there must me something propelled away of the same momentum with opposite sign. If the field produced is reacting to dark matter, we may not be able to measure its departure, but it is nontheless being propelled away.

When considering repulsion between a long cylindrical electromagnetic and earth's electromagnetic field the instantaneous rotational torque and instantaneous accelerating force will be a function of the relative field angle between the action and reaction field, the range, and strengths of the action and reaction fields.

The electrical input power can be estimated as a function of angular acceleration and angular velocity around the spin axis of the package, moment of inertia of the package, and acceleration and velocity of the package relative to earth.

This is simple force and angle relationships; the goo goo eyed dark matter stuff is way beyond me.

The permanent magnet will begin to roll away from the fixed magnet.

How does the conservation of momentum apply here?

Believe it or not, when the permanent magnet moves away, the fixed magnet and the entire earth move in the opposite direction an extremely minute amount.

The needle of a small magnetic compass is mechanically forced into the opposite direction. It is then released. The needle is accelerated by earths magnetic field as it begins to align to the equilibrium position.

How does the conservation of momentum apply here?

Same thing, the earth is pushing against the needle (or you are). In each case, the needle has very small mass, you and the earth have very large mass. The needle moves a lot, the earth and you very, very little.

What if there were some way to use the dipolar field of the Sun and planets as reaction fields?

You can get a reaction force from a magnetic field if you move from an intense region to a less intense region, or vice versa. That is how diamagnetic levitation works, or the force on a piece of iron in a magnetic field.

What if there were some way to use the dipolar field of the Sun and planets as reaction fields?

One of the things you can do in space is take advantage of the solar wind, the stream of particles that the sun emits. It doesn't violate momentum conservation. It's just a matter of putting up a big sail and capturing some of the solar wind's momentum the same way that sailors capture the momentum of the earthly wind.

This is certainly interesting.

I noticed something from the picture of the test fixture. The cabling appears to not be Kapton insulated and shrink tubing appears to be on these cables. This implies to me that this is only a rough vacuum chamber. This might be nothing more than a small RF cavity particle accelerator with the residual gasses being the material being accelerated. At such poor vacuum condition levels it is also much easier to ionize the atoms, too.

If my observation is the crux of how this drive works then this may still be of use for low orbit corrections, like the ISS application mentioned in the article. However this would be useless for interplanetary travel thrust. This scenario would also fit the non-scientific journal misunderstanding hyperbole while NASA investigates the suitability of using the gas that retards orbital velocity for thrust to maintain a low orbit.

Then again this may have been the initial goal of this experiment and more thrust than one expected from just this phenomena has been found. I can see force measuring retrofits being applied to existing accelerator facilities that already require Ultra High Vacuum conditions.

Yes, it all depends on vacuum quality measurements, and how that compares to the area near an object in LEO with decaying orbit. I like the concept, as the whatever that is doing is must be traveling very fast (way faster than chemical rocket gases) to produce any measurable thrust. Why not put a giant hood scoop on these satellites and make it work even better? I guess if it was large enough to matter, then the drag would really amount to a drag?

I cannot understand why nobody has tested this thing in a vacuum!

I think they tried to test in hard vacuum, epic fail.

I cannot understand why nobody has tested this thing in a vacuum!

OK, they have. If this is real, it's Science Fiction come to life! It's interesting that if it works, there seems to be no agreement in how it works.

http://www.nasaspaceflight.com/2015/04/evaluating-nasas-futuristic-em-drive/

I suspect we won't know whether or not this is a real effect for a few years yet. Only time (and more experiments) will tell. But it did get me thinking about how inefficient rocket propulsion is for interplanetary and orbital flight.

Basically we are using the same sort of propulsion to travel through space as we use for getting into orbit. That doesn't make sense to me and seems very inefficient with respect to propellant.

It should be possible to greatly improve propulsion once we're in space by finding ways of expelling propellant much faster. After all, momentum is mass times velocity, and really, when you think about it, the velocity of propellant exiting traditional rockets is pretty slow. Even if this EM drive turns out to be experimental error...it should at least make us rethink how we achieve thrust in space.

Keep in mind, I'm assuming the power is produced by a different source. I'm only viewing the propellant as the means of generating the "equal and opposite reaction". In other words, the propellant is only there to convert the energy generated by, let's say a fission generator, into motion.

Sometimes I think it's good to look at an opposing viewpoint. As exciting as it would be to have a reactionless drive, it's like holding a lottery ticket...It might be a big winner, but the odds are long. Extraordinary claims need extraordinary proof.

http://www.forbes.com/sites/ethansiegel/2015/05/04/no-nasa-did-not-accidentally-invent-warp-drive/

I definitely agree. I read somewhere where they pointed out the Faster than light neutrinos that turned out to be a jiggly wire. Skepticism is warranted until more results are in.

Just to be clear though, I wasn't suggesting a reactionless drive in my last comment. I'm saying a more efficient use of propellant might be beneficial. Just think of it as, every atom of propellant is precious and must be fired off with as high a velocity as possible to maximize the "reaction". I hope that makes sense.

Maybe a Bussard ramjet is what we need...

http://en.wikipedia.org/wiki/Bussard_ramjet

Question:

Does wave-particle duality come into play at all here? Supposedly, the thrust measured is much larger than what photon pressure could achieve, is that right?

Already asked and answered in the above quagmire?

Could the E-M field have any effect at all on space curvature?

Regarding wave-particle duality, it doesn't really show up here. Light in general has momentum, that's been known since the 1800s, so when it reflects off a surface the surface experiences an equal and opposite reaction, but that isn't what's happening here either according to the NASA researchers.

The vacuum continually has virtual particles and antiparticles that spring into existence and then annihilate. As I understand it, the guys doing the research are arguing the these virtual particles are being used as propellant. The microwave cavity is somehow preventing them from recombining as they ordinarily would and firing them off behind the engine (causing an equal and opposite reaction, ie thrust). This violates a number of generally accepted physical laws including but not limited to conservation of momentum. Though it's worth mentioning that scientists as a group misunderstand fundamental laws all the time (See Goddard and vacuum space flight). So we won't know for sure until the experiment is tested other places.

It's worth noting that the original designer of the drive (not from NASA) insists that the thrust can be accounted for by photon momentum from the microwave resonator, but most scientists seem to agree that his explanation is seriously flawed (I don't know enough to know myself). Obviously if other experiments confirm the measured thrust then the designer's explanation will be revisited.

I personally have no idea what's going on but if I'd have to bet I'd bet on experimental error.

That said, sometimes a mistake can introduce an interesting way of thinking. Thrust is essentially due to action and reaction. The action right now involves loads of propellant exiting a rocket at relatively slow speeds (compared to the speed of light). That is pretty inefficient (though effective for escaping Earth's gravity). I'm suggesting that there is probably an interesting drive waiting to be built that carries it's own propellant (doesn't need to grab it from the vacuum) but uses it far more efficiently .In other words it exits the drive at a much much higher speed producing more thrust per unit of propellant.

Perhaps they are incorrectly applying the laws of physics in this case, and there may be some relativistic correction for virtual particle mass being ejected (especially if it must travel in the frame of reference of the microwaves (as in a very high linear speed ion trap?????!) I can visualize it, but most definitely cannot put it on paper.

Perhaps the virtual particles have divergent trajectory as the are propelled outward, and cannot combine, without some use of the principles of linked behavior at a distance. Some brilliant physics graduate student somewhere will get his/her hands on this and make sausage out of it.

Also, will the virtual particles be viewed in the stationary frame (the rocket engine) as having a larger mass, less length, and therefore more speed as they accelerate away? Could it also mean that if this were true, would the particles annihilation not be "worth" a lot more energy due to relativistic masses under acceleration annihilating (linked at a distance)?

These are questions I can't answer. The scientific majority seems to believe the experiment is probably a mistake. Only future experiments can answer these questions.

True, that it is quite premature to assume NASA (and others) got this right the first time, after all, this is science at the edge of what is known. After X number of confirmatory results, and anything suspicious that perturbs the accelerometer (or straingauge) that is measuring thrust has been eliminated, then conjectures that are now out there can each weighed by merits, consistency with that which is known, and a complete operating theory will emerge.

I think the best experiment might be go ahead and put one of these bad boys on a test probe and launch it into high orbit. It should not be too hard to use laser interferometry or other observations (Doppler? Transit time?) to observe any changes in the orbit to a higher one. The thing is will they be able to accurately predict at what point the probe is ready to leave Earth orbit, and travel to Mars, etc.?

I think their (NASA researchers) plan is to do the experiment again at higher power. Their model predicts that at higher power their should be higher thrust. If that doesn't happen, or if the thrust is different than expected by a lot, then it most probably is experimental error. I'm not sure how expensive a probe is nowadays. That might be the easiest way to test it (throw it on a probe and try to use it). Plus you can be sure other experimenters will be testing their results, so we should get some feedback soon. If others fail to reproduce the effect then again it probably was experimental error.

Nasty bad slow to scroll link.

I suppose part of the problem would be NASA not wanting to put a nuclear reactor on a rocket that may explode. Hopefully we will have fusion soon and that can be used instead.

The Soviets (and probably still the Russians) have used a thermal Polonium 210 source to produce onboard electricity for some of their space probes, and as near as I can recall, it is pretty hard to cause that to explode. It the launch vehicle explodes, that is an entirely different matter.

I suppose one could use far subcritical masses (pieces) of the charge to such a reactor, and cannisterize them in virtually indestructible enclosures for launch (that could be re-used, and even use robotics to retrieve the pieces from the cannisters and load them into a thermopile. I would much rather also see either cold or hot fusion take this job. By the way, there are groups out there now claiming to have calorimetrically detected excess heat at least 20 times the input heat in certain cold fusion experiments.

This is still not to say the heat is "high quality - high temperature" heat, but it is entirely sufficient for some generation purposes. No one has really tested the phenomenon at anything like a useful steam temperature, but on a spacecraft, one does not require that. The likely candidates would be hermetically sealed engines and generators that utilize low-boiling super-critical fluids such as carbon dioxide. Helium filled units also can work off low thermal differential, and none of them have ultra-high efficiency at the projected temperatures. AFAICT, it only has to work (1) with 99.99% reliability, (2) produce all the power requirements of the craft once in space, and (3) not require any consumables, and be able to recycle any/all of the materials utilized for a really long extended mission. Gosh, that can't too hard, can it? LOL

Lol,

I know, right? It's not that complicated except where it's horribly complicated. Still, it feels like were close. I don't expect we'll get to another star in my lifetime...but I expect, if I'm lucky to live long enough, it will become plausible.

FYI, my previous response was worded ambiguously. Like you described, I was talking about the rocket exploding, not the nuclear reactor. I think they worry about an explosion and then atmospheric contamination. I would too. The politics of spaceflight is hard enough without throwing radioactive material into the atmosphere.

I too would much rather see fusion do the job. I think if Lockheed Martin is successful in their fusion ventures then we will see it start to be incorporated by NASA into probes.

Could be. Time will tell, but I think the hot fusion crowd will "get their day in the sun". So will the cold fusion folks. I think both will work in time, but on vastly different scales (at least at first).

I can see a large lift vehicle operating from a fusion (hot style) reactor of 100's MW power able to do a large chunk of the job (as long as there is something to be compressed and heated as in a jet aircraft engine). The real test will lie in conversion over to plasma drive in the outer reaches of earth atmosphere while still sub-orbital. Maybe somewhere in that zone, the impulse engine (EM engine) will be OK operational. Heck for all I know, it might work even as well or better in thick air?

I just don't think they will be able to scale the thing up to the point of useful for lift engine at the surface.

We have been flying RTGs for decades. All of our deep space missions use them.

There are designs that use closed loop reactors to drive Sterling generators. I dare to conjecture that our first attempt at this failed when only one side of a counter balancing system worked causing a high torque loss of attitude control and loss of high gain communication.

The use of nuclear power in space applications is an old and mature technology but has come at the cost of several very serious accidents resulting in wide spread contamination.

Because our environment is already so contaminated these accidents did not cause significant increases to total atmospheric "background" radiation; but in at least one case the pieces recovered would have caused death with a few hours of close contact.

I feel it is worth noting that although an accident may not cause a measurable increase in total background radiation any ingestion or body entry of the particles will cause carcinoma.

I may be wrong but I believe specific impulse increases as the square of the exhaust velocity.

Is the idea of EM drive to eliminate expendable fuel mass or is it to use what little mass that exists in the vacuum as propellant by collecting it and then accelerating it using electromagnetic methods; not unlike ion drive.

As I understand it the EM drive supposedly eliminates the need for propellant mass.

For the record, specific Impulse Isp is actually proportional to exhaust velocity. The specific inpulse dimension is seconds, and basically indicates how long 1 "pound" of fuel can produce 1 pound of thrust.

F=(mv)' = v*m'. Force (thrust) is time derivative of momentum, and exhaust velocity is constant. So force is proportional to time rate of change of mass (how fast fuel is used up).

Weight = g*m, where g is gravitational constant (32.2 ft/sec^2)

Isp=F/(g*m')=(v*m')/(g*m')=v/g

The solid state version uses DiLithium crystals!

Thinking about this thread, I recalled that once when I was young, I noticed that shaking a weight while standing on a spring type bathroom scale resulted in a lower weight indication. Later I found out that friction in the scale was causing a rectifier-like effect, rectifying the "ac" shaking action. Alas, no reactionless thrust.

Here is some speculation, not knowing the details of the experimental set up:

If some microwave radiation escaped the microwave cavity in this experiment, could it affect the force sensors? The most obvious effect would be some kind of diode rectification (copper oxide, possibly). A second, less likely possibility, might be conversion of the microwave energy to sound (resonance, perhaps), which gets rectified, bathroom scale fashion, into an indicated thrust.

I would assume that these things would have been checked out, preferable by someone skeptical, trying to disprove the hypothesis that thrust was being generated.

It's way too easy to fall in love with the dream of reactionless propulsion.