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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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.

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Hackaday Prize Entry: An EM Drive

As far as engineering feats of the 21st century go (as long as they turn out to be real), we’re looking at two things. Lockheed Martin might build a working, power generating fusion reactor in the next decade. That will solve every problem on the planet. The second is even more spectacular. It’s called the EM drive, and it will take humans to the stars. It violates the laws of physics, but it somehow works, and there’s a project on hackaday.io to replicate it.

The first thing to know about the EM drive is that it doesn’t use propellent. Instead, it simply dumps microwaves into a cavity and somehow produces thrust. This violates [Newton]’s third law of motion, “for every action there is an equal and opposite reaction.” Every rocket engine ever, from the Saturn V to ion thrusters on spacecraft now cruising around the solar system, use some sort of propellent. The EM drive does not; it simply dumps microwaves into a closed cavity. It breaks the tyranny of the rocket equation. If you strap a nuclear reactor to an EM drive, you’ll be seeing attack ships on fire off the shoulder of Orion, and C-beams glitter in the dark near the Tanhauser Gate.

Despite violating the laws of physics, Chinese researchers found this device produces thrust, and these experiments were replicated at Eagleworks at Johnson Space Center. No one can tell you why it works, but somehow it does, at least in the few tests completed so far.

If the EM drive isn’t just an experimental aberration, this is how we’re going to get to Alpha Centauri. Whoever explains how the EM drive works will get the Nobel, and [movax] over on hackaday.io is building one out of a broken microwave oven. It’s a fantastic project for the Hackaday Prize, and even if it doesn’t work, it makes for a great story for the grandkids.


The 2015 Hackaday Prize is sponsored by: