China claims it is testing an EmDrive propulsion system in space.
Dr. Chen Yue, Director of Commercial Satellite Technology for the China Academy of Space Technology (CAST) announced on December 10, 2016 that not only has China successfully tested EmDrives technology in its laboratories, but that a proof-of-concept is currently undergoing zero-g testing in orbit (according to the International Business Times, this test is taking place on the Tiangong 2 space station).
Unlike traditional engines (such as combustion and ion engines) that expel mass from the system to produce thrust, reactionless engines like the EmDrive use only electricity to generate movement. In the EmDrive, first proposed by Roger Shawyer, the microwave cavity is an asymmetric container, such as a truncated cone, with one end much larger than the other. At the narrower end, a source of electromagnetic energy (such as a magnetron) bombards the cavity with microwaves. These waves are contained and bounce off the cavity’s walls, creating electromagnetic resonance. Due to the imbalanced resonance from the complex geometry of a truncated cone, the electromagnetic field in the EmDrive becomes directionally dependent (anisotropic). In this case, the anisotropic electromagnetic field ‘pushes’ the EmDrive away from the direction of the cavity’s larger area end.
Gizmodo has a fascinating story about NASA scientists who appear to have proven that Roger Shawyer’s quantum vacuum plasma thruster, known as the EmDrive (a.k.a., Relativity Drive), actually works. But, they’re not sure exactly why.
Shawyer’s engine is extremely light and simple. It provides a thrust by “bouncing microwaves around in a closed container.” The microwaves are generated using electricity that can be provided by solar energy. No propellant is necessary, which means that this thrusters can work forever unless a hardware failure occurs. If real, this would be a major breakthrough in space propulsion technology.
Obviously, the entire thing sounded preposterous to everyone. In theory, this thing shouldn’t work at all. So people laughed and laughed and ignored him. Everyone except a team of Chinese scientists. They built one in 2009 and it worked: They were able to produce 720 millinewton, which is reportedly enough to build a satellite thruster. And still, nobody else believed it.
Now, American scientist Guido Fetta and a team at NASA Eagleworks—the advanced propulsion skunkworks led by Dr Harold “Sonny” White at the Johnson Space Center—have published a new paper that demonstrates that a similar engine working on the same principles does indeed produce thrust. Their model, however, produces much less thrust—just 30 to 50 micronewtons. But it works, which is amazing on its own. They haven’t explained why their engine works, but it does work.