NASA confirms the operation of the "impossible" wave engine that does not use reactive mass - EmDrive

Disclaimer: This article was written by a layman in this field. Corrections, comments and detailed comments are strongly encouraged.

The essence of the news

July 30th at the 50th AIAA / ASME / SAE / ASEE Joint Propulsion Conference - the fiftieth joint conference of the American Institute of Aeronautics and Astronautics, the American Community of Mechanical Engineers, the Society of Automotive Engineers and the American Community of Engineering Education devoted to motor systems, if you are interested in the meaning of abbreviations, representatives NASA labs have reported that EmDrive, a thrust-free thruster, works.

Principle of operation

Obviously, the reader, following the example of the world scientific community, skeptically arches an eyebrow relative to the previous phrase. Therefore, I will immediately give a description of the principle of engine operation , presented on the website of the inventor company.

In its most general form, the device consists of a magnetron and a reflective chamber of a specific shape that creates the resonance of an electromagnetic wave.

The principle of operation is based on the effect of pressure of electromagnetic radiation: microwave radiation puts pressure on the reflector. The shape of the pressure chamber on the reflectance b ofthe lower side is higher than the smaller. A logical objection arises that, according to Newtonian laws, such pressure in a closed system will only lead to a load on the chamber material. However, according to the creators, in this case it is necessary to use the Special Theory of Relativity, according to which, due to the near-light velocity of the wave, the reflective camera and wave must be considered in different reference systems and, therefore, the combination of reflector + wave becomes an open system and creates traction without the use of jet release. The strength of the wave is further increased due to the created resonance. Those interested in specific formulas can see them in the source above.


The first experimental sample: a copper-colored reflective chamber, a magnetron, and plenty of water cooling.

The first news about such an engine appeared in 2000, when the British Roger J. Shawyer founded the company Satellite Propulsion Research Ltd, which is developing this device. Despite the fact that a working prototype was made back in 2003 (the device created traction in barely noticeable, but sufficient to prove the working capacity of the 16 mN concept), full-fledged independent research was started only in 2008 - then the Chinese team of scientists carried out theoretical calculations and agreed that theory is viable. In 2010, the same team published a work in which it derived a formula for calculating the thrust of such an engine, and also stated that in the experiments a thrust of 720 mN (72 grams) was obtained. However, their work was met with great skepticism.

Finally, a US scientist, Guido Fetta, built his version of the “fuel-free” engine, operating on the same principle, but using not the shape of a camera reflector, but reflectors with different reflection coefficients, and convinced NASA to test it.

Test results from Eagleworks Laboratories were presented on July 30, 2014. The general meaning of the report can be reduced to “We are not sure how it works, but it works”: the researchers tried to avoid thinking about the physics of the engine and simply presented the test results. Excerpt from the report .

For the reliability of the tests, the laboratory staff conducted comparative tests of the “zero engine” - the same system configured with minor changes that prevent the appearance of traction, and also tested the working sample in different directions to eliminate possible errors caused by the influence of the electromagnetic field on the measuring equipment.

According to a NASA report, it was possible to achieve a thrust of 30-50 mN. Noticeably less than the previously announced result of the Chinese team, however, it is enough to confirm the functionality of such a system. Unfortunately, the amount of energy consumed was not indicated, so it’s still not possible to evaluate the effectiveness of such an engine.

Sources of information: one and two .

Possible application

The subsequent text is solely a reflection of the author.

I think that any space technology enthusiast will be able to bring up many possible situations where such an electric motor will be extremely useful. First of all, the launch of satellites into high Earth orbit. Now used for most of the weight of the device is sent to the geostationary orbit consists of fuel. Using EmDrive, the device can enter a high orbit, receiving energy from solar panels or RTGs.

A similar system can be used to study the solar system - moving with constant, albeit small acceleration, the spacecraft will be able to cover interplanetary distances much faster than using the modern system of the "initial kick" from a chemical rocket and flying along a ballistic trajectory.

A similar system is offered by ion engines, but, firstly, they still use a working fluid, which means that its amount imposes restrictions on the total amount of thrust that the engine can produce, not to mention that the fuel has mass. Secondly, judging by what has been seen, the EmDrive design is much simpler and cheaper than an ion engine: a reflective chamber, a magnetron, an energy source and a cooling system - all these parts are quite simple and have been tested for a long time.

Of course, so far we are talking only about extremely light vehicles - it remains to be seen whether it will be possible to create an engine with sufficient thrust so that it can be installed on a manned spacecraft or a spacecraft the size of a Curiosity interplanetary module. However, if this still turns out to be possible, the only limitation in interplanetary flights will be energy, and unlike fuel, we already know how to extract it in space.

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