Chinese say the ‘EmDrive’ may change the future of space propulsion
Chinese scientists have built and tested a British inventor’s design of a new type of space propulsion drive. Once scoffed as an impossible device by his British counterparts, China says that it not only works but it will change the satellite industry in a positive way.
Today, most satellites are launched into orbit and maintain their altitude and proper orbit by the use of fuels or compressed gasses. In fact, a good percentage of the weight of a satellite is composed of the fuel that keeps it at its proper position once in space. This added weight on satellites costs a lot, but now China says they can change all of this with this new and innovative propulsion system called the ‘EmDrive’. Currently the amount of thrust it produces is very small and only able to lift a few ounces, but in outer space that can amount to a lot of momentum over time.
A British engineer by the name of Roger Shaywer is the inventor of the new drive system, which he began the work on it in 2001 after he received a government grant from the United Kingdom’s Department of Trade and Industry. Soon thereafter, he started his own company, which he called the Satellite Propulsion Research (SPR) Ltd. In two years’ time he developed a version of his EmDrive system, which is a conical container that uses propulsion with resonating microwaves and supposedly results in a net thrust of force downward at the wide end of the container.
Immediately after Shawyer wrote on his findings with his invention, the scientific community scoffed at the idea and called it a just a little less than a sci-fi fantasy. Many fired back saying that the apparatus violated the law of conservation of momentum, which states that no closed system can give a net thrust.
Shawyer desperately tried to argue his case by saying that the microwaves were causing the thrust because they have a group velocity that is greater in a single direction. Shawyer said that Einstein’s special theory of relativity plays a role in how it works. Even still, his counterparts wouldn't have it and ignored anything he came back with.
The first test of the device occurred in 2003 and gave a reading of 16mN, which is very small but enough to prove that it worked. Just as they had previously, other scientists in his field of study ignored his findings, called it implausible and would not even look at it often quoting Newton’s laws of physics.
When China heard about the drive they decided to take a look at Shawyer's findings and see what the fuss was all about. Not only were they curious at his design but they went ahead and built and tested their own model. After running it for the first time, they are not only saying that it really does work but that it will change the satellite industry as we know it today.
The Chinese researchers were led by a Dr. Yang Juan who serves as a Professor of Propulsion Theory and Engineering of Aeronautics and Astronautics at the Northwestern Polytechnic University in Xi'an. The paper on the new system was called, "Net thrust measurement of propellantless microwave thruster," and was published by the Acta Physica Sinica journal.
In all aspects of space travel all initial propulsion relies on the simple fact that a gas is ejected out results in thrust. Once in space, all satellites must rely on a propellant to keep them in orbit or to make subtle changes to their position. This fuel will eventually run out and the satellite will lose its orbit position or make a reentry into the atmosphere due to earth’s gravity. With this new drive system it would mean no more fuel for satellites, which currently accounts for a lot of their mass at launch time as well. All of this added weight from more fuel translates to higher costs for the launch in the first place.
Dr. Juan and her team discovered that the drive system given as little as 2 kilowatts of power would produce up to 72 grams of thrust or about 720 mN. While this may not seem like much thrust, in a weightless environment it means a lot movement. To give a good example, the current ion drive (the XIPS thruster by Boeing) that is being experimented with by NASA uses twice as much power as the EmDrive and it produces less than one quarter the same thrust as the EmDrive. The EmDrive is also lighter in weight than the XIPS thruster.
Shawyer has big plans for this thruster and wants it to be able to produce more thrust so it can be used right here on terra firma. He is hoping that the latest tests coming out of China will back up his work and restore his standing in the scientific community. Having more funding will allow him to begin making a more powerful unit.
The amount of thrust the EmDrive produces is determined by the Q value of the cavity in the device. Shawyer claims that if he can implement some kind of superconductor with the drive he can boost its Q value, which in turn boosts its thrust by several thousand. Basically what Shawyer is hinting at is something along the lines of a flying car, and who doesn’t want a flying car?