The Myth Of Propellantless Space Propulsion Refuses To Die

In a Universe ruled by the harsh and unyielding laws of Physics, it’s often tempting to dream of mechanisms which defy these rigid restrictions. Although over the past hundred years we have made astounding progress in uncovering ways to work within these restrictions — including splitting and fusing atoms to liberate immense amounts of energy — there are those who dream of making reality a bit more magical. The concept of asymmetrical electrostatic propulsion is a major player here, with the EmDrive the infamous example. More recently [Dr. Charles Buhler] proposed trying it again, as part of his company Exodus Propulsion Technologies.

This slide from Dr. Buhler’s APEC presentation shows the custom-made vacuum chamber built to test their propellantless Propulsion drive in a simulated space environment. Image Credit: Exodus Propulsion Technologies, Buhler, et al.
This slide from Dr. Buhler’s APEC presentation shows the custom-made vacuum chamber built to test their propellantless Propulsion drive in a simulated space environment. Image Credit: Exodus Propulsion Technologies, Buhler, et al.

The problem with such propellantless space propulsion proposals is that they violate the core what we know about the physical rules, such as the conclusion by Newton that for any action there has to be an opposite reaction. If you induce an electrostatic field or whatever in some kind of device, you’d expect any kind of force (‘thrust’) this creates to act in all directions equally, ergo for thrust to exist, it has to push on something in the other direction. Rocket and ion engines (thrusters) solve this by using propellant that create the reaction mass.

The EmDrive was firmly disproven 2021 by [M. Tajmar] and colleagues in their paper titled High-accuracy thrust measurements of the EMDrive and elimination of false-positive effects as published in CEAS Space Journal, which had the researchers isolate the EmDrive from all possible outside influences. Since the reported thrust was on the level of a merest fraction of a Newton, even the impact from lighting in a room and body heat from the researchers can throw off the results, not to mention the heat developed from a microwave emitter as used in the EmDrive.

Meanwhile True Believers flock to the ‘Alt Propulsion Engineering Conference’ (APEC), as no self-respecting conference or scientific paper will accept such wishful claims. In the case of [Buhler], he claims that their new-and-improved EmDrive shows a force of 10 mN in a ‘stacked system’, yet no credible paper on the experiments can be found other than APEC presentations. Until their prototype is tested the way the EmDrive was tested by [M. Tajmar] et al., it seems fair to assume that the rules of physics as we know them today remain firmly intact.

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Hackaday Links: April 4, 2021

Can I just say that doing a links roundup article in a week that includes April Fool’s Day isn’t a fun job? Because it’s not. I mean, how can you take something like reports of X-rays flowing from Uranus seriously when they release the report on such a day? It sure looks like a legitimate story, though, and a pretty interesting one. Planets emitting X-rays isn’t really a new thing; we’ve known that Jupiter and Saturn are both powerful X-ray sources for decades. Even though Uranus is the odd child of our solar system, finding evidence for X-ray emissions buried in data captured by the Chandra observatory in 2007 was unexpected. Astronomers think the X-rays might be coming from Uranus’ rings, or they might be reflections of X-rays streaming out from the sun. Or, it might be the weird alignment of the gas giant’s magnetic field causing powerful aurorae that glow in the X-ray part of the spectrum. Whatever it is, it’s weird and beautiful, which all things considered isn’t a bad way for things to be.

Another potential jest-based story popped up this week about the seemingly impossible “EmDrive”. It seems that when you appear to be breaking the laws of physics, you’re probably doing it wrong, and careful lab tests showed that fuel-free propulsion isn’t here yet. One would think it was self-obvious that filling a closed asymmetrical chamber with microwaves would produce absolutely no thrust, but EmDrive proponents have reported small but measurable amounts of thrust from the improbable engine for years. A team at TU Dresden found otherwise, though. Even though they were able to measure a displacement of the engine, it appears to be from the test stand heating up and warping as the RF energy flowed into the drive chamber. By changing the way the engine was supported, they were able to cancel out the dimensional changes that were making it look like the EmDrive was actually working.

Want to use surface-mount parts, but don’t want to bother spinning up an SMD board? Not a problem, at least if you follow the lead of David Buchanan and perform no-surface surface-mount prototyping. We stumbled upon this on Twitter and thought it looked cool — it’s got a little bit of a circuit sculpture feeling, and we like the old-school look of plain 0.1″ perfboard. David reports that the flying leads are just enameled magnet wire; having done our share of scraping and cleaning magnet wire prior to soldering, we figured that part of the build must have been painful. We pinged David and asked if he had any shortcuts for prepping magnet wire, but alas, he says he just used a hot blob of solder and a little patience while the enamel cooked off. We still really like the style of this build, and we applaud the effort.

Speaking of stumbling across things, that’s one of the great joys of this job — falling down algorithmically generated rabbit holes as we troll about for the freshest hacks. One such serendipitous was this YouTube channel documenting a really nice jet engine build. We’ve seen plenty of jet engines before, but very few with afterburners like this one has. There’s also something deeply satisfying about the variable-throat nozzle that Praendy built for the engine — it’s a level of complexity that you don’t often see in hobbyist jet engines, and yet the mechanism is very simple and understandable.

The other rabbit hole we discovered was after reporting on this cool TIG tungsten grinding tool. That took us into The Metalist’s back catalog, where we found a lot of interesting stuff. But the real treat was this automatic tube polisher (video), which we have to say kept us guessing up to the very end. If you’ve got 12 minutes and you enjoy metalworking builds at all, watch it and see if you’re not surprised by the cleverness of this tool.

And finally, we had heard of the travails of Anatoli Bugorski before, but never in the detail presented in this disturbing video. (Embedded below.)

Who is Anatoli Bugorski, you ask? He is a Russian particle physicist who, while working in an accelerator lab in 1978, managed to get his head directly in the path of a 76 GeV proton beam. Despite getting a huge dose of radiation, Bugorski not only survived the accident but managed to finish his Ph.D. and went on to a long career in nuclear physics. He also got married and had a son. He was certainly injured — facial paralysis and partial deafness, mainly — but did not suffer anything like the gruesome fates of the Chernobyl firefighters or others receiving massive radiation doses. The video goes into some detail about how the accident happened — two light bulbs are better than one, it turns out. We enjoyed the video, but couldn’t stop thinking that Bugorski was the Russian atomic-age equivalent of Phineas Gage.

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Hackaday Links: December 18, 2016

You can fly a brick if it has offset mass and you can fly a microwave because it breaks the law of the conservation of momentum. A paper on the EM Drive was recently published by the Eagleworks team, and the results basically say, ‘if this works, it’s a terrible thruster that shouldn’t work’. Experts have weighed in, but now we might not have to wait for another test in the Eagleworks lab: China will fly an EM Drive on their space station. Will it work? Who knows.

The ESP32 is just now landing on workbenches around the globe, and already a few people are diving into promiscuous mode and WiFi packet injection.

The Large Hadron Collider is the most advanced piece of scientific apparatus ever built. It produces tons of data, and classifying this data is a challenge. The best pattern recognition unit is between your ears, so CERN is crowdsourcing the categorization of LHC data.

Holy crap this is cyberpunk. [SexyCyborg] created a makeup palette pen testing device thing out of a Rasberry Pi and a few bits and bobs sitting around in a parts drawer. The project is cool, but the photolog of the finished project is awesome. It’s exactly what you would use to break into the Weyland-Yutani database while evading government operatives on the rooftops of Kowloon Walled City before escaping via grappling hook shot into the belly of a spaceplane taking off.

The Mini NES is Nintendo’s most successful hardware offering since the N64. This tiny device, importantly packaged in a minified retro NES enclosure, is out of stock everywhere. That doesn’t matter because now there’s a mini Genesis. The cool kids had a Genesis. You want to be a cool kid, right? Mortal Kombat was better on the Genesis.

The Arduino (what once was two is again one) launched a new vowel-hating model: MKRZero. The narrow board is powered by USB or LiPo, centers around an Atmel SAMD21 Cortex-M0+ chip, and sports both an I2C breakout header and a microSD card slot. Just watch those levels as these pins are not 5v tolerant.

The American Association for the Advancement of Science is holding a Scientific Maker Exhibit during its annual meeting. This type of exhibit isn’t a poster or presentation — it’s just some table space and a chance to show off a 3D printed apparatus, a new type of sensor, equipment, or some other physical thing. Details in this PDF. This is actually cooler than it sounds, and a significant departure from the traditional poster or presentation found at every other scientific conference.

Did you know Hackaday has a retro edition made specifically for old computers connected to the Internet? That’s my baby, and it’s time for a refresh. If you have any feature requests you’d like to see, leave a note in the comments.

That NASA EM Drive Paper: An Expert Opinion

A week or two ago we featured a research paper from NASA scientists that reported a tiny but measurable thrust from an electromagnetic drive mounted on a torsion balance in a vacuum chamber. This was interesting news because electromagnetic drives do not eject mass in the way that a traditional rocket engine does, so any thrust they may produce would violate Newton’s Third Law. Either the Laws Of Physics are not as inviolate as we have been led to believe, or some other factor has evaded the attempts of the team to exclude or explain everything that might otherwise produce a force.

As you might imagine, opinion has entrenched itself on both sides of this issue. Those who believe that EM drives have allowed us to stumble upon some hitherto undiscovered branch of physics seized upon the fact that the NASA paper was peer-reviewed to support their case, while those who believe the mechanism through which the force is generated will eventually be explained by conventional means stuck to their guns. The rest of us who sit on the fence await further developments from either side with interest.

Over at Phys.org they have an interview from the University of Connecticut with [Brice Cassenti], a propulsion expert, which brings his specialist knowledge to the issue. He believes that eventually the results will be explained by conventional means, but explains why the paper made it through peer review and addresses some of the speculation about the device being tested in space. If you are firmly in one of the opposing camps the interview may not persuade you to change your mind, but it nevertheless makes for an interesting read.

If EM drives are of interest, you might find our overview from last year to be an illuminating read. Meanwhile our coverage of the NASA paper should give you some background to this story, and we’ve even had one entered in the Hackaday Prize.

EM Drive Paper Published By Eagleworks Team

There are one or two perennial scientific stories that sound just too good to be true, but if they delivered on their promise would represent a huge breakthrough and instantly obsolete entire fields. One example is so-called “cold fusion”, the idea that nuclear fusion could be sustained with a net energy release at room temperature rather than super-high temperature akin to that of the sun. We all wish it could work, but so far it has obstinately refused. As a TV actor portraying a space engineer of the future once said, one “cannae change the Laws of Physics“.
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Flying The Infinite Improbability Drive

Not since the cold fusion confusion of 1989 has the pop science media industry had a story like the EmDrive. The EmDrive is a propellantless thruster – a device that turns RF energy into force. If it works, it will revolutionize any technology that moves. Unlike rocket motors that use chemicals, cold gas, ions, or plasma, a spacecraft equipped with an EmDrive can cruise around the solar system using only solar panels. If it works, it will violate the known laws of physics.

After being tested in several laboratories around the world, including Eagleworks, NASA’s Advanced Propulsion Physics Laboratory, the concept of a device that produces thrust from only electricity is still not disproven, ridiculed, and ignored. For a device that violates the law of conservation of momentum, this is remarkable. Peer review of several experiments are ongoing, but [Paul] has a much more sensational idea: he’s building an EmDrive that will propel a cubesat.

Make no mistake, our current understanding of the universe is completely incompatible with the EmDrive. The idea of an engine that dumps microwave energy into a metal cone and somehow produce thrust is on the fringes of science. No sane academic physicist would pursue this line of research, and the mere supposition that the EmDrive might work is irresponsible. Until further peer-reviewed experiments are published, the EmDrive is the fanciful dream of a madman. That said, if it does work, we get helicarriers. Four EmDrives mounted to a Tesla Roadster would make a hovercar. Your grandchildren would only see Earth’s sun as a tiny speck in the night sky.

This isn’t [Paul]’s first attempt to create a working propellantless thruster. For last year’s Hackaday Prize, [Paul] built a baby EmDrive. Unlike every other EmDrive experiment that used 2.4GHz microwaves, [Paul] designed his engine to operate on 22 to 26 GHz. This means [Paul]’s is significantly smaller and can easily fit into a cubesat. If it works, this cubesat will be able to maintain its orbit indefinitely, fly to the moon and back, or go anywhere in the solar system provided the solar panels get enough light.

While [Paul]’s motivations in creating a citizen science version of the EmDrive are laudable, Hackaday.io’s own baby EmDrive does not display the requisite scientific rigor for a project of this magnitude. Experimental setups are ill-defined, graph axes are unlabeled, and there is not enough information to properly critique [Paul]’s baby EmDrive experiments.

That said, we can’t blame a guy for trying, and the EmDrive is still an active area of research with several papers under peer review. [Paul]’s plan of putting an EmDrive into orbit is putting the cart several miles ahead of the horse, but it is still a very cool project for this year’s Hackaday Prize.

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The EM Drive Might Not Work, But We Get Helicarriers If It Does

There is a device under test out there that promises to take humans to another star in a single lifetime. It means vacations on the moon, retiring at Saturn, and hovercars. If it turns out to be real, it’s the greatest invention of the 21st century. If not, it will be relegated to the history of terrible science right underneath the cold fusion fiasco. It is the EM drive, the electromagnetic drive, a reactionless thruster that operates only on RF energy. It supposedly violates the laws of conservation of momentum, but multiple independent lab tests have shown that it produces thrust. What’s the real story? That’s a little more complicated.

The EM Drive is a device that turns RF energy — radio waves — directly into thrust. This has obvious applications for spacecraft, enabling vacations on Mars, manned explorations of Saturn, and serious consideration of human colonization of other solar systems. The EM drive, if proven successful, would be one of the greatest inventions of all time. Despite the amazing amount of innovation the EM drive would enable, it’s actually a fairly simple device, and something that can be built out of a few copper sheets.

Continue reading “The EM Drive Might Not Work, But We Get Helicarriers If It Does”