Amid all other projects U.S., European, Japanese, and other space agencies are currently undertaking, the news about the EmDrive propulsion, that has a potential to forever change the technology used for deep space travels, passed relatively unnoticed outside scientific circles. Now that this “quantum vacuum plasma thruster” has been tested by four independent organizations, from three different countries, as presented at 65th International Astronautical Congress (IAC) held in Toronto from September 29th to October 3rd 2014, it might prove to be the most promising concept in the space propulsion technology ever.
EmDrive is a concept developed by Satellite Propulsion Research Ltd, a small UK-based company. Their engine model produces thrust by “harnessing the difference in radiation pressure on two opposing surfaces”. Its most amazing feature is that it doesn’t require any propellant. It works on electricity and electromagnetic radiation. The whole concept, which uses patented microwave technology, relies on Newton’s Second Law, where force is determined as the rate of change of momentum. Apparently, microwave photons pass through tapered waveguide against two reflectors which, due to the velocity difference at reflecting surfaces and thus produced difference in force, generate thrust (pardon author’s simplified layperson’s interpretation). Solar panels would be used to furnish the electricity which would then be converted into thrust.
So far the whole idea sounds amazing. The problem is that, at least at this stage, it doesn’t work. According to the Discover Magazine’s blog, written by Corey Powell, his correspondent Sean Carroll, physicists from Caltech, stated that measurements conducted in labs (primarily relating to recent NASA’s testing of similar machine) recorded “an incredibly tiny effect that could very easily be just noise.” Generally, the scientific community is in disbelief concerning this matter. An article on the subject published in New Scientist initiated a barrage of condemning comments. Many scientists have their theories about why such engine should not work (mostly because it doesn’t respect the law of momentum conservation) but no one so far gave a satisfactory explanation for why it could work, and why it does produce some kind of output.
However, Roger Shawyer, an engineer behind this concept, claims that his invention is not violating the principle of momentum conservation and the conservation of energy as the biggest objections to his work, and he believes additional tests (maybe with the different design and the scale of the models, A/N) will prove this phenomenon in the future. A trial flight program is being negotiated.
Whatever these test results prove at the end, this subject propelled many controversies regarding the distribution of UK government funds reserved for scientific projects, since Sawyer’s project was granted £250, 000 (≈$400, 000) without any supporting evidence from his peers.