Test Suggests NASA's Impossible EM Drive Will Work In Space

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Test Suggests NASA's Impossible EM Drive Will Work In Space

Postby KroLazuxy_87 » 2015-05-01 12:19pm

Lots of in-text links and some pictures I didn't bother to port over, feel free to follow through if you're curious.

New Test Suggests NASA's "Impossible" EM Drive Will Work In Space
George Dvorsky | 4/30/15

Last year, NASA’s advanced propulsion research wing made headlines by announcing the successful test of a physics-defying electromagnetic drive, or EM drive. Now, this futuristic engine, which could in theory propel objects to near-relativistic speeds, has been shown to work inside a space-like vacuum.

NASA Eagleworks made the announcement quite unassumingly via NASASpaceFlight.com. There’s also a major discussion going on about the engine and the physics that drives it at the site’s forum.

The EM drive is controversial in that it appears to violate conventional physics and the law of conservation of momentum; the engine, invented by British scientist Roger Sawyer, converts electric power to thrust without the need for any propellant by bouncing microwaves within a closed container. So, with no expulsion of propellant, there’s nothing to balance the change in the spacecraft’s momentum during acceleration. Hence the skepticism. But as stated by NASA Eagleworks scientist Harold White:
[T]he EM Drive’s thrust was due to the Quantum Vacuum (the quantum state with the lowest possible energy) behaving like propellant ions behave in a MagnetoHydroDynamics drive (a method electrifying propellant and then directing it with magnetic fields to push a spacecraft in the opposite direction) for spacecraft propulsion.

The trouble with this theory, however, is that it might not work in a closed vacuum. After last year’s tests of the engine, which weren’t performed in a vacuum, skeptics argued that the measured thrust was attributable to environmental conditions external to the drive, such as natural thermal convection currents arising from microwave heating.

The recent experiment, however, addressed this concern head-on, while also demonstrating the engine’s potential to work in space.
The NASASpaceflight.com group has given consideration to whether the experimental measurements of thrust force were the result of an artifact. Despite considerable effort within the NASASpaceflight.com forum to dismiss the reported thrust as an artifact, the EM Drive results have yet to be falsified.

After consistent reports of thrust measurements from EM Drive experiments in the US, UK, and China – at thrust levels several thousand times in excess of a photon rocket, and now under hard vacuum conditions – the question of where the thrust is coming from deserves serious inquiry.

Serious inquiry, indeed. It’s crucial now that these tests be analyzed, replicated, and confirmed elsewhere. A peer-review and formal paper would also seem to be in order lest we get too carried away with these results. But wow. Just wow.

It’s still early days, but the implications are mind-boggling to say the least. A full-fledged EM drive could be used on everything from satellites working in low Earth orbit, to missions to the Moon, Mars, and the outer solar system.

EM drives could also be used on multi-generation spaceships for interstellar travel. A journey to Alpha Centauri, which is “just” 4.3 light-years away, suddenly wouldn’t be so daunting. An EM drive working under a constant one milli-g acceleration would propel a ship to about 9.4% the speed of light, resulting in a total travel time of 92 years. But that’s without the need for deceleration; should we wish to make a stop at Alpha Centauri, we’d have to add another 38 years to the trip. Not a big deal by any extent of the imagination.


Fair warning: My physics is elementary. I understand enough to clearly know why this drive shouldn't work, but I have no idea what the proposed explanations are talking about. (Damn theoretical quantum physics)

Science is certainly my forte though and it seems that for whatever reason, they're getting results in increasingly carefully controlled experiments. That's exciting as hell - to me. I just hope this continues to pan out over the future years of research.

It certainly wouldn't be the first time science and humanity discovered something before understanding it.
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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Borgholio » 2015-05-01 01:00pm

Yeah there was thread about this awhile back. The general idea (and I'm not much on the physics either) is that generating EM radiation in an enclosed box somehow causes the box to move. The problem is that you can't move without thrust, which the box doesn't generate. And yet...supposedly it moves.

But it doesn't stop there. A ton of sites are already claiming that NASA is ready to build a .1c drive and the next stop is FTL. I think people are really getting ahead of themselves here. It could turn out to be like that particle experiment last year where they thought they measured a particle going faster than light, only to find out it was a faulty sensor.
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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Guardsman Bass » 2015-05-01 05:07pm

I'm calling bullshit until it gets independently duplicated outside of NASA. The presence of Harold White's commentary in particular makes me wary - he's had a history at NASA of making these big "breakthrough" announcements (namely on Warp Drive) only to pull back and become wary whenever someone asked for details or independent duplication.
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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Sky Captain » 2015-05-02 02:43am

It is already tested by research teams in UK and China an they all get thrust force that shouldn't be there according to physics we know.

What is really needed is test in space to eliminate any possible lab errors. Build satellite fitted with EM drive launch into orbit and power it up. If it can maneuver with EM thrust then the drive just works whatever the physics behind it is.

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby jwl » 2015-05-02 03:33am

Sky Captain wrote:It is already tested by research teams in UK and China an they all get thrust force that shouldn't be there according to physics we know.

What is really needed is test in space to eliminate any possible lab errors. Build satellite fitted with EM drive launch into orbit and power it up. If it can maneuver with EM thrust then the drive just works whatever the physics behind it is.

The thing is, for it to work effectively you apparently need a nuclear reactor to power it. Nobody is going to send a nuclear reactor into space for the sake of a drive that might not work.

Anyway, here is the original article:
Evaluating NASA’s Futuristic EM Drive

A group at NASA’s Johnson Space Center has successfully tested an electromagnetic (EM) propulsion drive in a vacuum – a major breakthrough for a multi-year international effort comprising several competing research teams. Thrust measurements of the EM Drive defy classical physics’ expectations that such a closed (microwave) cavity should be unusable for space propulsion because of the law of conservation of momentum.

EM Drive:

Last summer, NASA Eagleworks – an advanced propulsion research group led by Dr. Harold “Sonny” White at the Johnson Space Center (JSC) – made waves throughout the scientific and technical communities when the group presented their test results on July 28-30, 2014, at the 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference in Cleveland, Ohio.

Those results related to experimental testing of an EM Drive – a concept that originated around 2001 when a small UK company, Satellite Propulsion Research Ltd (SPR), under Roger J. Shawyer, started a Research and Development (R&D) program.

The concept of an EM Drive as put forth by SPR was that electromagnetic microwave cavities might provide for the direct conversion of electrical energy to thrust without the need to expel any propellant.

2015-04-19-005958This lack of expulsion of propellant from the drive was met with initial skepticism within the scientific community because this lack of propellant expulsion would leave nothing to balance the change in the spacecraft’s momentum if it were able to accelerate.

However, in 2010, Prof. Juan Yang in China began publishing about her research into EM Drive technology, culminating in her 2012 paper reporting higher input power (2.5kW) and tested thrust (720mN) levels of an EM Drive.

In 2014, Prof. Yang’s papers reported extensive tests involving internal temperature measurements with embedded thermocouples.

It was reported (in SPR Ltd.’s website) that if the Chinese EM Drive were to be installed in the International Space Station (ISS) and work as reported, it could provide the necessary delta-V (change in velocity needed to perform an on-orbit maneuver) to compensate for the Station’s orbital decay and thus eliminate the requirement of re-boosts from visiting vehicles. Despite these reports, Prof. Yang offered no scientifically-accepted explanation as to how the EM Drive can produce propulsion in space.

2015-04-19-010043Dr. White proposed that the EM Drive’s thrust was due to the Quantum Vacuum (the quantum state with the lowest possible energy) behaving like propellant ions behave in a MagnetoHydroDynamics drive (a method electrifying propellant and then directing it with magnetic fields to push a spacecraft in the opposite direction) for spacecraft propulsion.

In Dr. White’s model, the propellant ions of the MagnetoHydroDynamics drive are replaced as the fuel source by the virtual particles of the Quantum Vacuum, eliminating the need to carry propellant.

This model was also met with criticism in the scientific community because the Quantum Vacuum cannot be ionized and is understood to be “frame-less” – meaning you cannot “push” against it, as required for momentum.

The tests reported by Dr. White’s team in July 2014 were not conducted in a vacuum, and none of the tests reported by Prof. Yang in China or Mr. Shawyer in the UK were conducted in a vacuum either.

The scientific community met these NASA tests with skepticism and a number of physicists proposed that the measured thrust force in the US, UK, and China tests was more likely due to (external to the EM Drive cavity) natural thermal convection currents arising from microwave heating (internal to the EM Drive cavity).

However, Paul March, an engineer at NASA Eagleworks, recently reported in NASASpaceFlight.com’s forum (on a thread now over 500,000 views) that NASA has successfully tested their EM Drive in a hard vacuum – the first time any organization has reported such a successful test.

To this end, NASA Eagleworks has now nullified the prevailing hypothesis that thrust measurements were due to thermal convection.

2015-04-26-182409A community of enthusiasts, engineers, and scientists on several continents joined forces on the NASASpaceflight.com EM Drive forum to thoroughly examine the experiments and discuss theories of operation of the EM Drive.

The quality of forum discussions attracted the attention of EagleWorks team member Paul March at NASA, who has shared testing and background information with the group in order to fill in information gaps and further the dialogue.

This synergy between NASASpaceflight.com contributors and NASA has resulted in several contributions to the body of knowledge about the EM Drive.

The NASASpaceflight.com group has given consideration to whether the experimental measurements of thrust force were the result of an artifact. Despite considerable effort within the NASASpaceflight.com forum to dismiss the reported thrust as an artifact, the EM Drive results have yet to be falsified.

After consistent reports of thrust measurements from EM Drive experiments in the US, UK, and China – at thrust levels several thousand times in excess of a photon rocket, and now under hard vacuum conditions – the question of where the thrust is coming from deserves serious inquiry.

Applications:

The applications of such a propulsion drive are multi-fold, ranging from low Earth orbit (LEO) operations, to transit missions to the Moon, Mars, and the outer solar system, to multi-generation spaceships for interstellar travel.

Under these application considerations, the closest-to-home potential use of EM Drive technology would be for LEO space stations – such as the International Space Station.

2015-04-19-010224In terms of the Station, propellant-less propulsion could amount to significant savings by drastically reducing fuel resupply missions to the Station and eliminate the need for visiting-vehicle re-boost maneuvers.

The elimination of these currently necessary re-boost maneuvers would potentially reduce stress on the Station’s structure and allow for a pro-longed operational period for the ISS and future LEO space stations.

Likewise, EM drive technology could also be applied to geostationary orbit (GEO) satellites around Earth.

For a typical geostationary communications satellite with a 6kW (kilowatt) solar power capacity, replacing the conventional apogee engine, attitude thrusters, and propellant volume with an EM Drive would result in a reduction of the launch mass from 3 tons to 1.3 tons.

The satellite would be launched into LEO, where its solar arrays and antennas would be deployed. The EM-drive would then propel the satellite in a spiral trajectory up to GEO in 36 days.

2015-04-19-010251Moving out from LEO, Mr. March, from NASA EagleWorks, noted that a spacecraft equipped with EM drive technology could surpass the performance expectations of the WarpStar-I concept vehicle.

If such a similar vehicle were equipped with an EM Drive, it could enable travel from the surface of Earth to the surface of the moon within four hours.

Such a vehicle would be capable of carrying two to six passengers and luggage and would be able to return to Earth in the same four-hour interval using one load of hydrogen and oxygen for fuel cell-derived electrical power, assuming a 500 to 1,000 Newton/kW efficiency EM Drive system.

While the current maximum reported efficiency is close to only 1 Newton/kW (Prof. Yang’s experiments in China), Mr. March noted that such an increase in efficiency is most likely achievable within the next 50 years provided that current EM Drive propulsion conjectures are close to accurate.

Far more ambitious applications for the EM Drive were presented by Dr. White and include crewed missions to Mars as well as to the outer planets.

Specifically, these two proposed missions (to Mars and the outer planets) would use a 2 MegaWatt Nuclear Electric Propulsion spacecraft equipped with an EM Drive with a thrust/powerInput of 0.4 Newton/kW.

With this design, a mission to Mars would result in a 70-day transit from Earth to the red planet, a 90-day stay at Mars, and then another 70-day return transit to Earth.

See Also

EM Drive Updates
Advanced Concepts Forum
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According to Dr. White, “A 90 metric ton, 2 MegaWatt nuclear electric propulsion mission to Mars [would have] considerable reduction in transit times due to having a thrust-to-mass ratio greater than the gravitational acceleration of the Sun (0.6 milli-g’s at 1 Astronomical Unit).”

Furthermore, this type of mission would have the added benefit of requiring only a “single heavy lift launch vehicle” as compared to “a current conjunction-class Mars mission using chemical propulsion systems, which would require multiple heavy lift launch vehicles.”

Presenting at the “Human Outer Solar System Exploration via Q-Thruster Technology” panel at IEEE, 2014, Mr. Joosten and Dr. White explained that “only 12 days would be utilized spiraling up from a 400 km low Earth orbit to achieve escape velocity and only 5 days spiraling down to a 400 km low Mars orbit.”

While these spiral trajectories around Earth would have to be carefully designed to avoid or minimize time in the most problematic regions of the Van Allen radiation belts that could expose crewmembers to undesirable levels of radiation, Mr. Joosten and Dr. White note that “These relatively rapid transits would argue for mission strategies where the ‘Q-Ship’ (EM Drive ship) operates between the lowest orbits possible to minimize the launch requirements of crew and supplies from Earth and lander complexity at Mars.”

Moreover, this type of EM Drive-enabled mission could negate the need to bring along, for the duration of the mission, a high-speed reentry vehicle to return a Mars crew back to the Earth’s surface because “By quickly spiraling into Earth orbit at the end of the mission, the crew could readily be retrieved via a ‘ground-up’ launch.

“While the fast Mars transits that Q-Thruster technology [EM drive] could enable would be revolutionary, the independence from the limitations of departure and arrival windows may ultimately be more so,” added Mr. Joosten and Dr. White.

This means that an EM drive ship mission could be designed without consideration of the every-two-year interplanetary conjunction launch windows that currently govern Earth-Mars transit missions and could help stabilize and provide more routine Mars crew rotation timetables.

This same elimination of inter-planetary conjunction-enabled launch windows would be applied to crewed missions to the outer planets as well.

For such a mission, such as a crewed flight to the outer planets – specifically, a Titan/Enceladus mission at Saturn – an EM Drive would allow for a 9-month transit period from Earth to Saturn, a 6-month in-situ mission at Titan, another 6-month in-situ mission at Enceladus, and a 9-month return trip to Earth. This would result in a total mission duration of just 32 months.

However, EM drive applications are not limited to Mars or outer solar system targets.

Applications of this technology in deep space missions have already received conceptual outlines.

In particular, the Alpha Centauri system, the closest star system to our solar system at just 4.3 lights year’s distance, received specific mention as a potential mission destination.

Mr. Joosten and Dr. White stated that “a one-way, non-decelerating trip to Alpha Centauri under a constant one milli-g acceleration” from an EM drive would result in an arrival speed of 9.4 percent the speed of light and result in a total transit time from Earth to Alpha Centauri of just 92 years.

However, if the intentions of such a mission were to perform in-situ observations and experiments in the Alpha Centauri system, then deceleration would be needed.

This added component would result in a 130-year transit time from Earth to Alpha Centauri – which is still a significant improvement over the multi-thousand year timetable such a mission would take using current chemical propulsion technology.

The speeds discussed in the Alpha Centauri mission proposal are sufficiently low that relativity effects are negligible.

Bringing EM Drives to reality:

While such mission proposals are important to consider, equally as important are the considerations toward development of the needed technology and procurement long-lead items necessary to make this power technology a reality.

Specifically, a useful EM Drive for space travel would need a nuclear power plant of 1.0 MWe (Megawatts-electric) to 100 MWe.

2015-04-19-010710While that sounds significant, the U.S. Navy currently builds 220 MW-thermal reactors for its “Boomer” Ohio class ICBM vehicles.

Thus, the technology to build such reactors is available, and the technology needed to build such a device for space-based operations has been around since the 1980s.

The limiting factors for further testing and development of this potentially revolutionary space exploration technology are funding to verify and characterize its operations, and the political will to develop nuclear power for space applications.

Progress Update:

On April 5, 2015, Paul March reported at NASAspaceflight.com’s Forum that Dr. White and Dr. Jerry Vera at NASA Eagleworks have just created a new computational code that models the EM Drive’s thrust as a three-dimensional magnetohydrodynamic flow of electron-positron virtual particles.

These simulations explain why in NASA’s experiments it was necessary to insert a high density polyethylene (HDPE) dielectric into the EM Drive, while the experiments in the UK and China were able to measure thrust without a dielectric insert.

The code shows two reasons for this: 1) the experiments in the UK and China used (unlike the ones in the US) a magnetron to generate the microwaves and 2) the experiments in the UK and China were performed with much higher input power: up to 2.5 kiloWatts, compared to less than 100 Watts in the US experiments.

In the US tests, microwave frequency generation was controlled via a voltage-controlled oscillator whose signal was passed to a variable voltage attenuator. The tests performed in the UK and China used, instead, magnetron microwave sources (as used in home-use microwave ovens) for their experiments.

The magnetron generates amplitude, frequency and phase modulation of the carrier wave (FM modulation bandwidth on the order of +/-20 MHz, at tested natural frequencies of ~2.5 GHz). Dr. White’s computer simulation shows that the modulation generated by the magnetron results in greater thrust force.

2015-04-19-010503Dr. White’s computer analysis also shows that increasing the input power focuses the virtual particle flow from near omnidirectional at the low powers used in the NASA experiments, to a much more focused jet like beam at the higher power (kilowatts as compared to less than 100 Watts) used in the UK and China experiments.

The simulation for the 100 Watts input power (as used in the latest tests at NASA) predicted only ~50 microNewtons (in agreement with the experiments) using the HDPE dielectric insert, while the 10 kiloWatts simulation (without a dielectric) predicted a thrust level of ~6.0 Newtons. At 100 kiloWatts the prediction is ~1300 Newton thrust.

The computer code also shows that the efficiency, as measured by the thrust to input power ratio, decreases at input powers exceeding 50 kiloWatts.

A note of caution is that Dr. White’s simulations do not assume that the Quantum Vacuum is indestructible and immutable. The mainstream physics community assumes the Quantum Vacuum is indestructible and immutable because of the experimental observation that a fundamental particle like an electron (or a positron) has the same properties (e.g. mass, charge or spin), regardless of when or where the particle was created, whether now or in the early universe, through astrophysical processes or in a laboratory.

Another reason is that the Quantum Vacuum is assumed to be the lowest possible (time-averaged) energy that a quantum physical system may have, and therefore it should not be possible to extract momentum or energy from the Quantum Vacuum.

Due to these predictions by Dr. White’s computer simulations NASA Eagleworks has started to build a 100 Watt to 1,200 Watt waveguide magnetron microwave power system that will drive an aluminum EM Drive shaped like a truncated cone.

Initially a teeter-totter balance system will be used in ambient conditions to see if similar thrust levels (0.016 to 0.3 Newton) as reported in the US and China can be reproduced at NASA with this approach.

For the last three years, Dr. White’s team has been conducting experiments to find out whether it is possible to measure, with an interferometer, a distortion of spacetime produced by time-varying electromagnetic fields.

The ultimate goal is to find out whether it is possible for a spacecraft traveling at conventional speeds to achieve effective superluminal speed by contracting space in front of it and expanding space behind it. The experimental results so far had been inconclusive.

During the first two weeks of April of this year, NASA Eagleworks may have finally obtained conclusive results. This time they used a short, cylindrical, aluminum resonant cavity excited at a natural frequency of 1.48 GHz with an input power of 30 Watts.

2015-04-26-182647This is essentially a pill-box shaped EM Drive, with much higher electric-field intensity, aligned in the axial direction. The interferometer’s laser light goes through small holes in the EM Drive.

Over 27,000 cycles of data (each 1.5 sec cycle energizing the system for 0.75 sec and de-energizing it for 0.75 sec) were averaged to obtain a power spectrum that revealed a signal frequency of 0.65 Hz with amplitude clearly above system noise. Four additional tests were successfully conducted that demonstrated repeatability.

One possible explanation for the optical path length change is that it is due to refraction of the air. The NASA team examined this possibility and concluded that it is not likely that the measured change is due to transient air heating because the experiment’s visibility threshold is forty times larger than the calculated effect from air considering atmospheric heating.

Encouraged by these results, NASA Eagleworks plans to next conduct these interferometer tests in a vacuum.

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

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Simon_Jester » 2015-05-02 01:40pm

KroLazuxy_87 wrote:...But as stated by NASA Eagleworks scientist Harold White:
[T]he EM Drive’s thrust was due to the Quantum Vacuum (the quantum state with the lowest possible energy) behaving like propellant ions behave in a MagnetoHydroDynamics drive (a method electrifying propellant and then directing it with magnetic fields to push a spacecraft in the opposite direction) for spacecraft propulsion.
Thing is, if radio waves in a box could do this, you would think we'd already know. See, microwave and radio-frequency cavities are a mature technology. We use them all the time for antennas and other such applications, and we have done so for over seventy years. The physics of what goes on inside such a cavity is well understood. It's not an exotic mystery magic thing.

So any phenomenon about radio waves bouncing around inside a box that produces noticeable results would tend to have caused "gee that's funny" moments in someone's megawatt-class radio antenna, or in the RF cavities of particle accelerators, or something like that.

In this test, the alleged fact that the box buzzes or creaks or 'vibrates' at 0.65 Hertz... Why 0.65? Is that a frequency associated with anything important about the system? It's about two cycles of vibration per three seconds, slow enough that it could just as easily be caused by something mundane like the guy at the other end of the lab rocking back and forth on his feet and bumping the test bench rhythmically. Or traffic outside the building.

Serious inquiry, indeed. It’s crucial now that these tests be analyzed, replicated, and confirmed elsewhere. A peer-review and formal paper would also seem to be in order lest we get too carried away with these results. But wow. Just wow.

It’s still early days, but the implications are mind-boggling to say the least. A full-fledged EM drive could be used on everything from satellites working in low Earth orbit, to missions to the Moon, Mars, and the outer solar system.
I'd restrain my enthusiasm if I were you. There are a lot more ways to gimmick such a test. More ways than there are reasons to think this particular means of making a reactionless drive actually work.

Science is certainly my forte though and it seems that for whatever reason, they're getting results in increasingly carefully controlled experiments. That's exciting as hell - to me. I just hope this continues to pan out over the future years of research.
So far we have two experiments, from the same guy, who personally has a history of issuing premature sensational crank announcement.s I'm suspicious.

jwl wrote:
Sky Captain wrote:It is already tested by research teams in UK and China an they all get thrust force that shouldn't be there according to physics we know.

What is really needed is test in space to eliminate any possible lab errors. Build satellite fitted with EM drive launch into orbit and power it up. If it can maneuver with EM thrust then the drive just works whatever the physics behind it is.
The thing is, for it to work effectively you apparently need a nuclear reactor to power it. Nobody is going to send a nuclear reactor into space for the sake of a drive that might not work.
If it actually runs on radio waves or magnetism, then unless I am BADLY mistaken...

...it should work if you just plug it into a battery of solar panels. You just get less force, and thus less acceleration, which means you need to leave the drive turned on longer to observe it actually moving under its own power.

That's not a show-stopper. That's actually an excellent test, reminding me of the Alecto vs. Rattlesnake trials that proved propellers are better than paddlewheels, by the simplest possible expedient: the propeller ship proved able to tow the paddlewheel ship backwards even when its engines were running at top speed.

And I predict that this RF-cavity-powered reactionless drive will fail that test.




Anyway, here is the original article:
Evaluating NASA’s Futuristic EM Drive

A group at NASA’s Johnson Space Center has successfully tested an electromagnetic (EM) propulsion drive in a vacuum – a major breakthrough for a multi-year international effort comprising several competing research teams. Thrust measurements of the EM Drive defy classical physics’ expectations that such a closed (microwave) cavity should be unusable for space propulsion because of the law of conservation of momentum.

EM Drive:

Last summer, NASA Eagleworks – an advanced propulsion research group led by Dr. Harold “Sonny” White at the Johnson Space Center (JSC) – made waves throughout the scientific and technical communities when the group presented their test results on July 28-30, 2014, at the 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference in Cleveland, Ohio.

Those results related to experimental testing of an EM Drive – a concept that originated around 2001 when a small UK company, Satellite Propulsion Research Ltd (SPR), under Roger J. Shawyer, started a Research and Development (R&D) program.

The concept of an EM Drive as put forth by SPR was that electromagnetic microwave cavities might provide for the direct conversion of electrical energy to thrust without the need to expel any propellant.

2015-04-19-005958This lack of expulsion of propellant from the drive was met with initial skepticism within the scientific community because this lack of propellant expulsion would leave nothing to balance the change in the spacecraft’s momentum if it were able to accelerate.

However, in 2010, Prof. Juan Yang in China began publishing about her research into EM Drive technology, culminating in her 2012 paper reporting higher input power (2.5kW) and tested thrust (720mN) levels of an EM Drive.

In 2014, Prof. Yang’s papers reported extensive tests involving internal temperature measurements with embedded thermocouples.

It was reported (in SPR Ltd.’s website) that if the Chinese EM Drive were to be installed in the International Space Station (ISS) and work as reported, it could provide the necessary delta-V (change in velocity needed to perform an on-orbit maneuver) to compensate for the Station’s orbital decay and thus eliminate the requirement of re-boosts from visiting vehicles. Despite these reports, Prof. Yang offered no scientifically-accepted explanation as to how the EM Drive can produce propulsion in space.

2015-04-19-010043Dr. White proposed that the EM Drive’s thrust was due to the Quantum Vacuum (the quantum state with the lowest possible energy) behaving like propellant ions behave in a MagnetoHydroDynamics drive (a method electrifying propellant and then directing it with magnetic fields to push a spacecraft in the opposite direction) for spacecraft propulsion.

In Dr. White’s model, the propellant ions of the MagnetoHydroDynamics drive are replaced as the fuel source by the virtual particles of the Quantum Vacuum, eliminating the need to carry propellant.

This model was also met with criticism in the scientific community because the Quantum Vacuum cannot be ionized and is understood to be “frame-less” – meaning you cannot “push” against it, as required for momentum.

The tests reported by Dr. White’s team in July 2014 were not conducted in a vacuum, and none of the tests reported by Prof. Yang in China or Mr. Shawyer in the UK were conducted in a vacuum either.

The scientific community met these NASA tests with skepticism and a number of physicists proposed that the measured thrust force in the US, UK, and China tests was more likely due to (external to the EM Drive cavity) natural thermal convection currents arising from microwave heating (internal to the EM Drive cavity).

However, Paul March, an engineer at NASA Eagleworks, recently reported in NASASpaceFlight.com’s forum (on a thread now over 500,000 views) that NASA has successfully tested their EM Drive in a hard vacuum – the first time any organization has reported such a successful test.

To this end, NASA Eagleworks has now nullified the prevailing hypothesis that thrust measurements were due to thermal convection.

2015-04-26-182409A community of enthusiasts, engineers, and scientists on several continents joined forces on the NASASpaceflight.com EM Drive forum to thoroughly examine the experiments and discuss theories of operation of the EM Drive.

The quality of forum discussions attracted the attention of EagleWorks team member Paul March at NASA, who has shared testing and background information with the group in order to fill in information gaps and further the dialogue.

This synergy between NASASpaceflight.com contributors and NASA has resulted in several contributions to the body of knowledge about the EM Drive.

The NASASpaceflight.com group has given consideration to whether the experimental measurements of thrust force were the result of an artifact. Despite considerable effort within the NASASpaceflight.com forum to dismiss the reported thrust as an artifact, the EM Drive results have yet to be falsified.

After consistent reports of thrust measurements from EM Drive experiments in the US, UK, and China – at thrust levels several thousand times in excess of a photon rocket, and now under hard vacuum conditions – the question of where the thrust is coming from deserves serious inquiry.

Applications:

The applications of such a propulsion drive are multi-fold, ranging from low Earth orbit (LEO) operations, to transit missions to the Moon, Mars, and the outer solar system, to multi-generation spaceships for interstellar travel.

Under these application considerations, the closest-to-home potential use of EM Drive technology would be for LEO space stations – such as the International Space Station.

2015-04-19-010224In terms of the Station, propellant-less propulsion could amount to significant savings by drastically reducing fuel resupply missions to the Station and eliminate the need for visiting-vehicle re-boost maneuvers.

The elimination of these currently necessary re-boost maneuvers would potentially reduce stress on the Station’s structure and allow for a pro-longed operational period for the ISS and future LEO space stations.

Likewise, EM drive technology could also be applied to geostationary orbit (GEO) satellites around Earth.

For a typical geostationary communications satellite with a 6kW (kilowatt) solar power capacity, replacing the conventional apogee engine, attitude thrusters, and propellant volume with an EM Drive would result in a reduction of the launch mass from 3 tons to 1.3 tons.

The satellite would be launched into LEO, where its solar arrays and antennas would be deployed. The EM-drive would then propel the satellite in a spiral trajectory up to GEO in 36 days.

2015-04-19-010251Moving out from LEO, Mr. March, from NASA EagleWorks, noted that a spacecraft equipped with EM drive technology could surpass the performance expectations of the WarpStar-I concept vehicle.

If such a similar vehicle were equipped with an EM Drive, it could enable travel from the surface of Earth to the surface of the moon within four hours.

Such a vehicle would be capable of carrying two to six passengers and luggage and would be able to return to Earth in the same four-hour interval using one load of hydrogen and oxygen for fuel cell-derived electrical power, assuming a 500 to 1,000 Newton/kW efficiency EM Drive system.

While the current maximum reported efficiency is close to only 1 Newton/kW (Prof. Yang’s experiments in China), Mr. March noted that such an increase in efficiency is most likely achievable within the next 50 years provided that current EM Drive propulsion conjectures are close to accurate.

Far more ambitious applications for the EM Drive were presented by Dr. White and include crewed missions to Mars as well as to the outer planets.

Specifically, these two proposed missions (to Mars and the outer planets) would use a 2 MegaWatt Nuclear Electric Propulsion spacecraft equipped with an EM Drive with a thrust/powerInput of 0.4 Newton/kW.

With this design, a mission to Mars would result in a 70-day transit from Earth to the red planet, a 90-day stay at Mars, and then another 70-day return transit to Earth.

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According to Dr. White, “A 90 metric ton, 2 MegaWatt nuclear electric propulsion mission to Mars [would have] considerable reduction in transit times due to having a thrust-to-mass ratio greater than the gravitational acceleration of the Sun (0.6 milli-g’s at 1 Astronomical Unit).”

Furthermore, this type of mission would have the added benefit of requiring only a “single heavy lift launch vehicle” as compared to “a current conjunction-class Mars mission using chemical propulsion systems, which would require multiple heavy lift launch vehicles.”

Presenting at the “Human Outer Solar System Exploration via Q-Thruster Technology” panel at IEEE, 2014, Mr. Joosten and Dr. White explained that “only 12 days would be utilized spiraling up from a 400 km low Earth orbit to achieve escape velocity and only 5 days spiraling down to a 400 km low Mars orbit.”

While these spiral trajectories around Earth would have to be carefully designed to avoid or minimize time in the most problematic regions of the Van Allen radiation belts that could expose crewmembers to undesirable levels of radiation, Mr. Joosten and Dr. White note that “These relatively rapid transits would argue for mission strategies where the ‘Q-Ship’ (EM Drive ship) operates between the lowest orbits possible to minimize the launch requirements of crew and supplies from Earth and lander complexity at Mars.”

Moreover, this type of EM Drive-enabled mission could negate the need to bring along, for the duration of the mission, a high-speed reentry vehicle to return a Mars crew back to the Earth’s surface because “By quickly spiraling into Earth orbit at the end of the mission, the crew could readily be retrieved via a ‘ground-up’ launch.

“While the fast Mars transits that Q-Thruster technology [EM drive] could enable would be revolutionary, the independence from the limitations of departure and arrival windows may ultimately be more so,” added Mr. Joosten and Dr. White.

This means that an EM drive ship mission could be designed without consideration of the every-two-year interplanetary conjunction launch windows that currently govern Earth-Mars transit missions and could help stabilize and provide more routine Mars crew rotation timetables.

This same elimination of inter-planetary conjunction-enabled launch windows would be applied to crewed missions to the outer planets as well.

For such a mission, such as a crewed flight to the outer planets – specifically, a Titan/Enceladus mission at Saturn – an EM Drive would allow for a 9-month transit period from Earth to Saturn, a 6-month in-situ mission at Titan, another 6-month in-situ mission at Enceladus, and a 9-month return trip to Earth. This would result in a total mission duration of just 32 months.

However, EM drive applications are not limited to Mars or outer solar system targets.

Applications of this technology in deep space missions have already received conceptual outlines.

In particular, the Alpha Centauri system, the closest star system to our solar system at just 4.3 lights year’s distance, received specific mention as a potential mission destination.

Mr. Joosten and Dr. White stated that “a one-way, non-decelerating trip to Alpha Centauri under a constant one milli-g acceleration” from an EM drive would result in an arrival speed of 9.4 percent the speed of light and result in a total transit time from Earth to Alpha Centauri of just 92 years.

However, if the intentions of such a mission were to perform in-situ observations and experiments in the Alpha Centauri system, then deceleration would be needed.

This added component would result in a 130-year transit time from Earth to Alpha Centauri – which is still a significant improvement over the multi-thousand year timetable such a mission would take using current chemical propulsion technology.

The speeds discussed in the Alpha Centauri mission proposal are sufficiently low that relativity effects are negligible.

Bringing EM Drives to reality:

While such mission proposals are important to consider, equally as important are the considerations toward development of the needed technology and procurement long-lead items necessary to make this power technology a reality.

Specifically, a useful EM Drive for space travel would need a nuclear power plant of 1.0 MWe (Megawatts-electric) to 100 MWe.

2015-04-19-010710While that sounds significant, the U.S. Navy currently builds 220 MW-thermal reactors for its “Boomer” Ohio class ICBM vehicles.

Thus, the technology to build such reactors is available, and the technology needed to build such a device for space-based operations has been around since the 1980s.

The limiting factors for further testing and development of this potentially revolutionary space exploration technology are funding to verify and characterize its operations, and the political will to develop nuclear power for space applications.

Progress Update:

On April 5, 2015, Paul March reported at NASAspaceflight.com’s Forum that Dr. White and Dr. Jerry Vera at NASA Eagleworks have just created a new computational code that models the EM Drive’s thrust as a three-dimensional magnetohydrodynamic flow of electron-positron virtual particles.

These simulations explain why in NASA’s experiments it was necessary to insert a high density polyethylene (HDPE) dielectric into the EM Drive, while the experiments in the UK and China were able to measure thrust without a dielectric insert.

The code shows two reasons for this: 1) the experiments in the UK and China used (unlike the ones in the US) a magnetron to generate the microwaves and 2) the experiments in the UK and China were performed with much higher input power: up to 2.5 kiloWatts, compared to less than 100 Watts in the US experiments.

In the US tests, microwave frequency generation was controlled via a voltage-controlled oscillator whose signal was passed to a variable voltage attenuator. The tests performed in the UK and China used, instead, magnetron microwave sources (as used in home-use microwave ovens) for their experiments.

The magnetron generates amplitude, frequency and phase modulation of the carrier wave (FM modulation bandwidth on the order of +/-20 MHz, at tested natural frequencies of ~2.5 GHz). Dr. White’s computer simulation shows that the modulation generated by the magnetron results in greater thrust force.

2015-04-19-010503Dr. White’s computer analysis also shows that increasing the input power focuses the virtual particle flow from near omnidirectional at the low powers used in the NASA experiments, to a much more focused jet like beam at the higher power (kilowatts as compared to less than 100 Watts) used in the UK and China experiments.

The simulation for the 100 Watts input power (as used in the latest tests at NASA) predicted only ~50 microNewtons (in agreement with the experiments) using the HDPE dielectric insert, while the 10 kiloWatts simulation (without a dielectric) predicted a thrust level of ~6.0 Newtons. At 100 kiloWatts the prediction is ~1300 Newton thrust.

The computer code also shows that the efficiency, as measured by the thrust to input power ratio, decreases at input powers exceeding 50 kiloWatts.

A note of caution is that Dr. White’s simulations do not assume that the Quantum Vacuum is indestructible and immutable. The mainstream physics community assumes the Quantum Vacuum is indestructible and immutable because of the experimental observation that a fundamental particle like an electron (or a positron) has the same properties (e.g. mass, charge or spin), regardless of when or where the particle was created, whether now or in the early universe, through astrophysical processes or in a laboratory.

Another reason is that the Quantum Vacuum is assumed to be the lowest possible (time-averaged) energy that a quantum physical system may have, and therefore it should not be possible to extract momentum or energy from the Quantum Vacuum.

Due to these predictions by Dr. White’s computer simulations NASA Eagleworks has started to build a 100 Watt to 1,200 Watt waveguide magnetron microwave power system that will drive an aluminum EM Drive shaped like a truncated cone.

Initially a teeter-totter balance system will be used in ambient conditions to see if similar thrust levels (0.016 to 0.3 Newton) as reported in the US and China can be reproduced at NASA with this approach.

For the last three years, Dr. White’s team has been conducting experiments to find out whether it is possible to measure, with an interferometer, a distortion of spacetime produced by time-varying electromagnetic fields.

The ultimate goal is to find out whether it is possible for a spacecraft traveling at conventional speeds to achieve effective superluminal speed by contracting space in front of it and expanding space behind it. The experimental results so far had been inconclusive.

During the first two weeks of April of this year, NASA Eagleworks may have finally obtained conclusive results. This time they used a short, cylindrical, aluminum resonant cavity excited at a natural frequency of 1.48 GHz with an input power of 30 Watts.

2015-04-26-182647This is essentially a pill-box shaped EM Drive, with much higher electric-field intensity, aligned in the axial direction. The interferometer’s laser light goes through small holes in the EM Drive.

Over 27,000 cycles of data (each 1.5 sec cycle energizing the system for 0.75 sec and de-energizing it for 0.75 sec) were averaged to obtain a power spectrum that revealed a signal frequency of 0.65 Hz with amplitude clearly above system noise. Four additional tests were successfully conducted that demonstrated repeatability.

One possible explanation for the optical path length change is that it is due to refraction of the air. The NASA team examined this possibility and concluded that it is not likely that the measured change is due to transient air heating because the experiment’s visibility threshold is forty times larger than the calculated effect from air considering atmospheric heating.

Encouraged by these results, NASA Eagleworks plans to next conduct these interferometer tests in a vacuum.

http://www.nasaspaceflight.com/2015/04/evaluating-nasas-futuristic-em-drive/[/quote]
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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby jwl » 2015-05-02 03:16pm

Thing is, if radio waves in a box could do this, you would think we'd already know. See, microwave and radio-frequency cavities are a mature technology. We use them all the time for antennas and other such applications, and we have done so for over seventy years. The physics of what goes on inside such a cavity is well understood. It's not an exotic mystery magic thing.

So any phenomenon about radio waves bouncing around inside a box that produces noticeable results would tend to have caused "gee that's funny" moments in someone's megawatt-class radio antenna, or in the RF cavities of particle accelerators, or something like that.

In this test, the alleged fact that the box buzzes or creaks or 'vibrates' at 0.65 Hertz... Why 0.65? Is that a frequency associated with anything important about the system? It's about two cycles of vibration per three seconds, slow enough that it could just as easily be caused by something mundane like the guy at the other end of the lab rocking back and forth on his feet and bumping the test bench rhythmically. Or traffic outside the building.

That's a completely different test to the one taking up the bulk of the article. In that case, the em drive was made in a short cylinder shape rather than a frustum specifically to avoid generating thrust; they didn't want thrust, they wanted to use it to investigate the quantum vaccum. What they're looking for here is not force but a path length difference for the photons, because they are looking for distortions is spacetime or something because they are warp drive people.

Apparently, they've found something, and they say they've ruled out refraction as a reason for it. That's it.
Simon_Jester wrote:
jwl wrote:
Sky Captain wrote:It is already tested by research teams in UK and China an they all get thrust force that shouldn't be there according to physics we know.

What is really needed is test in space to eliminate any possible lab errors. Build satellite fitted with EM drive launch into orbit and power it up. If it can maneuver with EM thrust then the drive just works whatever the physics behind it is.
The thing is, for it to work effectively you apparently need a nuclear reactor to power it. Nobody is going to send a nuclear reactor into space for the sake of a drive that might not work.
If it actually runs on radio waves or magnetism, then unless I am BADLY mistaken...

...it should work if you just plug it into a battery of solar panels. You just get less force, and thus less acceleration, which means you need to leave the drive turned on longer to observe it actually moving under its own power.

Good point, but it depends whether the thrust is sufficient to overcome errors. According to the article:

Dr. White’s computer analysis also shows that increasing the input power focuses the virtual particle flow from near omnidirectional at the low powers used in the NASA experiments, to a much more focused jet like beam at the higher power (kilowatts as compared to less than 100 Watts) used in the UK and China experiments.

The simulation for the 100 Watts input power (as used in the latest tests at NASA) predicted only ~50 microNewtons (in agreement with the experiments) using the HDPE dielectric insert, while the 10 kiloWatts simulation (without a dielectric) predicted a thrust level of ~6.0 Newtons. At 100 kiloWatts the prediction is ~1300 Newton thrust.

The computer code also shows that the efficiency, as measured by the thrust to input power ratio, decreases at input powers exceeding 50 kiloWatts.

However, in 2010, Prof. Juan Yang in China began publishing about her research into EM Drive technology, culminating in her 2012 paper reporting higher input power (2.5kW) and tested thrust (720mN) levels of an EM Drive.


So, apparently, if this is right:
100 W in -> 0.00005 N out
2 500 W in -> 0.72 N out
10 000 W in -> 6 N out
100 000 W in -> 1300 N out

I don't know what power satellite solar panels produce or what force is required for any useful test with satellites. Do you? If we can work this out we'll know whether testing it on a satellite is feasible. Personally, I think they're better off just hooking it straight up to a 100 kW source on earth. If it really gives off 1300 N it'd be able to lift up a person, it's pretty hard to say that is down to some sort of experimental error.

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby jwl » 2015-05-02 04:15pm

I've found the forum post that first talks about the hard vacuum test:
Folks:

The Eagleworks Lab is still working on the copper frustum thruster that was reported on last summer at the AIAA/JPC. We have now confirmed that there is a thrust signature in a hard vacuum (~5.0x10^-6 Torr) in both the forward direction, (approx. +50 micro-Newton (uN) with 50W at 1,937.115 MHz), and the reversed direction, (up to -16uN with a failing RF amp), when the thruster is rotated 180 degrees on the torque pendulum. However we continue to fight through RF amplifier failures brought on by having to operate them in a hard vacuum with few $$$ resources to fix them when they break, so the desired data is coming along very slowly. We are still working on obtaining enough data though that will allow us to go to Glenn Research Center (GRC) for a replication effort in the next few months. However that will only happen if we can make the thrust signature large enough since the GRC thrust stand can only measure down to ~50uN, so we have to get the thrust signature up to at least 100uN before we can go to GRC.

As to the theoretical side of Q-Thrusters, Dr. White has just developed the first cut at a quantum vacuum (QV) based plasma code written in C+ under Windows/Unix and VMD visualization software that utilizes the COMSOL E&M derived field data for a given thruster geometry that allows one to track the movement and velocity of a subset of the QV's electron/positron neutral plasma pairs in the thruster over time as they respond to the applied time varying RF E&M fields in the copper frustum resonant cavity and to each other. This package also allows one to calculate the expected thrust for a given input power and quality factor of the frustum resonant cavity based of standard plasma rocket physics. So far the estimated thrust verses experimental observations are within 2% for the first experimental data run I compared it to, but we still have a long, long road ahead of us of experimental validation before we have any real confidence in this very new Q-Thruster design tool.

Best, Paul March

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1326608#msg1326608

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Sky Captain » 2015-05-02 04:20pm

jwl wrote:I don't know what power satellite solar panels produce or what force is required for any useful test with satellites. Do you? If we can work this out we'll know whether testing it on a satellite is feasible.


2.5 kw would not be a problem and even that is excessive for test. Ion engines used on sattellites produce around 100 mN thrust and it is enough to maneuver heavy geostationary sattellites. It just takes some time. On a dedicated lightweight test sattelite even 10 mN would be enough to cause detectable velocity changes in orbit.

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby jwl » 2015-05-02 05:18pm

Sky Captain wrote:
jwl wrote:I don't know what power satellite solar panels produce or what force is required for any useful test with satellites. Do you? If we can work this out we'll know whether testing it on a satellite is feasible.


2.5 kw would not be a problem and even that is excessive for test. Ion engines used on sattellites produce around 100 mN thrust and it is enough to maneuver heavy geostationary sattellites. It just takes some time. On a dedicated lightweight test sattelite even 10 mN would be enough to cause detectable velocity changes in orbit.

Nice. In which case sending it up there might work out as a test. Although I don't know about this lightweight test satellite. Isn't the emdrive itself going to weigh quite a bit?

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Simon_Jester » 2015-05-02 06:25pm

jwl wrote:That's a completely different test to the one taking up the bulk of the article. In that case, the em drive was made in a short cylinder shape rather than a frustum specifically to avoid generating thrust; they didn't want thrust, they wanted to use it to investigate the quantum vaccum. What they're looking for here is not force but a path length difference for the photons, because they are looking for distortions is spacetime or something because they are warp drive people.

Apparently, they've found something, and they say they've ruled out refraction as a reason for it. That's it.
Thing is, they are asserting that a properly shaped RF cavity generates thrust.

Lots of people have built lots of RF cavities with lots of shapes for lots of reasons over the year. No one has ever accidentally built one that inadvertently rips itself off its own mountings or even noticeably stresses them or otherwise shows any sign of significant vibrations or forces generated purely by the fact that radio frequency waves are ricocheting around inside.

It is possible that this bunch of people with their new cavity are the only ones who've ever tried this particular configuration, and that only this configuration does anything.

But since it is also very possible that this bunch of people are cranks, given their pronouncements about warp drives and so on...

I would advise taking their claims extremely suspiciously. There are a lot of good reasons to think they're wrong, until such time as they provide an utterly astounding test to prove that they're right.

Good point, but it depends whether the thrust is sufficient to overcome errors. According to the article:

Dr. White’s computer analysis also shows that increasing the input power focuses the virtual particle flow from near omnidirectional at the low powers used in the NASA experiments, to a much more focused jet like beam at the higher power (kilowatts as compared to less than 100 Watts) used in the UK and China experiments.

The simulation for the 100 Watts input power (as used in the latest tests at NASA) predicted only ~50 microNewtons (in agreement with the experiments) using the HDPE dielectric insert, while the 10 kiloWatts simulation (without a dielectric) predicted a thrust level of ~6.0 Newtons. At 100 kiloWatts the prediction is ~1300 Newton thrust.
If anyone's actually willing to put their money where their mouth is, this isn't a major problem. A few kilowatts on a satellite isn't that hard, when it's in direct sunlight. And if you were doing literally nothing but testing this reactionless drive, you could afford to pack extra solar panels onto the satellite.

Also, kilowatts not kiloWatts and newtons not Newtons, but that's not your fault it's theirs.

Ideally, though, the space-based test should NOT be done by funding the group that originally designed this thing, but rather by building the device to their specifications. If they turn out not to be scam artists or quacks there will be plenty of time to honor and reward them later; if they ARE scam artists, handing them hundreds of thousands to build a satellite is a bad idea.

I don't know what power satellite solar panels produce or what force is required for any useful test with satellites. Do you? If we can work this out we'll know whether testing it on a satellite is feasible. Personally, I think they're better off just hooking it straight up to a 100 kW source on earth. If it really gives off 1300 N it'd be able to lift up a person, it's pretty hard to say that is down to some sort of experimental error.
That would also be reasonable and we could do that really easily, so I approve of this idea.

The point is that we should NOT seriously maintain that this thing works until it does something that is unambiguously, clearly, not possible unless it works. Because there are a lot of prior reasons to doubt it.
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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Sky Captain » 2015-05-03 02:31am

Simon_Jester wrote:But since it is also very possible that this bunch of people are cranks, given their pronouncements about warp drives and so on...


How would you explain Chinese test which also measured thrust? Apparently they got as much as 720 mN force which would be hard to explain as lab error. I hope more teams build this thing and test it at higher power levels since experiment setup seems fairly easy to replicate. Either they found some common error causing false thrust measurements or someone is going to get Nobel prize in physics.

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby bilateralrope » 2015-05-03 03:18am

I see two possibilities:
1 - The EM drive works. Figuring out how, and the implications of that, is obviously a big deal.
2 - There is some systematic error everyone testing the drive is making. Figuring out exactly what that error is could be important if that same error is being made in other experiments.

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Sky Captain » 2015-05-03 03:26am

One other cheap test could be to put the gadget on a small boat in indoor pool. If they get several hundred mN force it will have noticeable effect on a boat.

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Simon_Jester » 2015-05-03 04:10am

Sky Captain wrote:
Simon_Jester wrote:But since it is also very possible that this bunch of people are cranks, given their pronouncements about warp drives and so on...
How would you explain Chinese test which also measured thrust? Apparently they got as much as 720 mN force which would be hard to explain as lab error. I hope more teams build this thing and test it at higher power levels since experiment setup seems fairly easy to replicate. Either they found some common error causing false thrust measurements or someone is going to get Nobel prize in physics.
To be clear, are you saying the thrust measurement test has been done by White's group and a Chinese group?

Or only by the Chinese group?

If these experiments are going to continue to be done with the engine fixed to a test bench, then I am going to want to see very widespread reproduction. Even the hypothesis "two groups working independently are quacks/cranks/frauds" is probable compared to "the law of conservation of momentum is wrong." The hypothesis "one group is a bunch of quacks/frauds/cranks" would be an incredibly likely bet compared to conservation of momentum being wrong.

And, hm. Assuming the Chinese group was acting in good faith, the most likely explanation for how a few hundred millinewtons of force could be exerted might be self-forces created by the electric currents used to power the device, since we're talking about hundreds of watts as I recall.

If you have, for example, a pair of wires carrying parallel currents, they tend to attract each other- opposite currents will tend to repel. If you are not careful setting up your circuits, it wouldn't be that hard to configure things so that a few hundred millinewtons of force will be exerted on one part or another of that configuration.

Alternatively, an instrument could be miscalibrated or uncalibrated; that's off the top of my head because I'm going to bed soon and don't have time to do a detailed analysis of the Chinese experimental setup.
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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby bilateralrope » 2015-05-03 05:00am

Sky Captain wrote:One other cheap test could be to put the gadget on a small boat in indoor pool. If they get several hundred mN force it will have noticeable effect on a boat.


That doesn't rule out the possibility of thermal effects pushing the boat around. A spot of water gets heated unevenly. This causes the water to move and cooler water to replace it. Now you have some measurable thrust cause by the drive that can be explained by well established physical theories. Your test has been ruined.

The only way I know of to remove that systematic error is to test the drive in a vacuum.

Simon_Jester wrote:If these experiments are going to continue to be done with the engine fixed to a test bench, then I am going to want to see very widespread reproduction. Even the hypothesis "two groups working independently are quacks/cranks/frauds" is probable compared to "the law of conservation of momentum is wrong." The hypothesis "one group is a bunch of quacks/frauds/cranks" would be an incredibly likely bet compared to conservation of momentum being wrong.

Are there enough groups capable of doing the testing in a vacuum to satisfy you ?

Me, this is an area of physics that I know I have a very poor understanding of. Which means that I'm not sure if it's possible to convince me that the EM drive works using only earth based testing. My lack of knowledge will mean I'll need some serious explanation to rule out systematic errors.

An orbital test is a different matter. There I do understand enough that I can be convinced by a single test, if it keeps producing thrust for long enough.

If you were at NASA, are there any earth-based tests you would want done before you start seriously looking at an orbital test ?

The only one I can think of is running it until it breaks, then figure out why it broke. Mainly to make sure that it can survive long enough in orbit to produce a useful result.

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby jwl » 2015-05-03 08:11am

Sky Captain wrote:
Simon_Jester wrote:But since it is also very possible that this bunch of people are cranks, given their pronouncements about warp drives and so on...


How would you explain Chinese test which also measured thrust? Apparently they got as much as 720 mN force which would be hard to explain as lab error. I hope more teams build this thing and test it at higher power levels since experiment setup seems fairly easy to replicate. Either they found some common error causing false thrust measurements or someone is going to get Nobel prize in physics.

The reason people care about this test in particular was that it was done in a vacuum. Some people thought the signal from earlier tests, including the Chinese one, was due to convection currents from the metal heating up and this rules that possibility out. Anyway, they said in the first post on the matter that they are looking for replication, they just need to get the force above 100uN so they can measure it. If it's just a matter of getting a bigger power source they should be able to do that.

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Simon_Jester » 2015-05-03 12:37pm

bilateralrope wrote:Are there enough groups capable of doing the testing in a vacuum to satisfy you ?
It would be better to do the test in atmosphere but at very high power levels.

It would also be better to use deliberately misshapen RF cavities- because any effect caused by magnetism or heating or whatever in the wires would still work even if the microwave cavity were not of the 'correct' shape for this experiment.

When you have a strange and improbable scientific phenomenon that supposedly only happens when you get the apparatus design just right, one of the first things you try is deliberately NOT getting the design right and seeing if it works anyway. The classic example is the N-ray fraud, which supposedly involved rays refracted through an aluminum prism. Eventually it occurred to someone to test whether the 'discoverer' still got the same results after someone stole his aluminum prism as he got with the prism. He did, which rather decisively proved that there was no such thing as N-rays bending through the prism and that the whole thing was a fraud.

Me, this is an area of physics that I know I have a very poor understanding of. Which means that I'm not sure if it's possible to convince me that the EM drive works using only earth based testing. My lack of knowledge will mean I'll need some serious explanation to rule out systematic errors.
If the claims that this thing produces several kilowatts of thrust at megawatt power levels are valid, then a ground level test at high power would be pretty conclusive.

But all these conveniently subtle effects we observe at 'only' a kilowatt or so of power aren't very convincing because they're hard to conclusively distinguish from background noise.

An orbital test is a different matter. There I do understand enough that I can be convinced by a single test, if it keeps producing thrust for long enough.
With a slight caveat for "in case it turns out the whole thing was somehow a fraud," so would I. A drive that works in space is a drive that works in space.
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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Sky Captain » 2015-05-03 02:41pm

Simon_Jester wrote:To be clear, are you saying the thrust measurement test has been done by White's group and a Chinese group?

Or only by the Chinese group?


Nasaspaceflight article said Chinese experiment with 2,5 kw power source produced 720 mN force while NASA team measured only 50 microN force in vacuum chamber, but with only 50 W power.

A test with power source in kilowatt range so the force if produced would be well above the noise probably is quickest way how to get more conclusive results.

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby mr friendly guy » 2015-05-03 08:17pm

I remember the arguments for this boils down to]
Opponents : Its breaks conservation of momentum
Proponents : No it doesn't because of <insert reason which I don't think I understand>.

Ultimately it will boil down to experimental work to try and minimise errors.
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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Terralthra » 2015-05-04 12:35am

Reactionless drives would be awesome, in that it would allow small craft built by amateurs to destroy cities. Unfortunately, conservation of momentum is one of those really key things that most of classical mechanics 100% relies on. As Simon says, if it could be broken by odd echoes and eddies in quantum flux within an EM reflector, more than one person would probably have noticed it by now. We bounce a lot of EM fields around these days.

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Sky Captain » 2015-05-04 01:57am

Terralthra wrote:Reactionless drives would be awesome, in that it would allow small craft built by amateurs to destroy cities. Unfortunately, conservation of momentum is one of those really key things that most of classical mechanics 100% relies on. As Simon says, if it could be broken by odd echoes and eddies in quantum flux within an EM reflector, more than one person would probably have noticed it by now. We bounce a lot of EM fields around these days.


As I understand the drive needs some specially shaped cavity to work, maybe that shape has no other applications and was never built for some other purpose. Also forces generated are small enough to not be noticeable if you are not looking for them. If my kitchen microwave started to produce few mN thrust I would never notice it.

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Simon_Jester » 2015-05-04 02:44am

The thing is, if there's one shape that makes it work well, there would generally (as in, this is true in most other kinds of physical phenomena) be other shapes that work less well. The odds of no one ever accidentally stumbling on one of them...

Well frankly, it's conceivable but it's just not that likely a priori, especially since we have LITERALLY not observed a single inexplicable phenomenon related to electromagnetism in the past half century or so. It seems pretty well understood by now.

Moreover, there are plenty of RF cavities that run at megawatt power levels, and those would generate quite noticeable thrust if any of them happened to be even vaguely like a 'quantum flux engine' in shape.

Again, I'm not saying something like this is absolutely 100% inconceivable, but it's not very plausible, not a thing that a person with a healthy level of skepticism should be quick to accept. Not given just how much of the world we have observed to behave the way we'd expect, given how we think magnetic, electromagnetism, and quantum physics interact.
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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby jwl » 2015-05-04 03:40am

Terralthra wrote:Reactionless drives would be awesome, in that it would allow small craft built by amateurs to destroy cities.

....How does that work?

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Re: Test Suggests NASA's Impossible EM Drive Will Work In Sp

Postby Darmalus » 2015-05-04 04:40am

jwl wrote:
Terralthra wrote:Reactionless drives would be awesome, in that it would allow small craft built by amateurs to destroy cities.

....How does that work?

You assume said armature spacecraft has an unlimited power source (solar?) and time to build up to city-smashing velocities and a unobstructed orbit to do this in.


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