The EmDrive is a new type of rocket engine first proposed by British scientist/electrical engineer Roger Shawyer in 1999. Unlike conventional space rocket engines, the EmDrive doesn’t require any kind of propellant (also known as a reaction mass) to make propulsion possible, and hence partially disobeying Newton’s Third Law:

“To each action there’s an equal and opposite reaction”.

Despite the fact that this seems to violate the known laws of physics, a prototype device was submitted to NASA’s Eagleworks lab for testing which came back positive, reports Digital Trends.

The paper resulting from the test, “Measurement of Impulsive Thrust from a Closed Radio Frequency Cavity in Vacuum” by Harold White et al., was accepted for publication in the peer reviewed Journal Of Propulsion And Power, by AIAA according to Dr. José Rodal, NASA Spaceflight forums.

How does it work?

The idea is that electricity is converted into microwaves, and the microwave photons are fired into a truncated cone-shaped closed metal cavity. When fired into the cavity, the microwave photons push against the large end of the cone, causing the small end to accelerate in the opposite direction yet obeying a part of Newton’s Law.

Controversy

Many academics in the international scientific community don’t believe it is remotely possible for the EmDrive to work. They say that according to the law of conservation of momentum, in order for a thruster to gain momentum in one direction, a propellant must be expelled in the opposite one, and since the EmDrive is a closed system with no propellant, it violates our understanding of physics.

In 2006, an article by the New Scientist caused massive backlash from readers, academics and armchair scientists, and Shawyer waseven accused of fraud. Despite this, the UK government was satisfied that Shawyer’s results were legitimate and continued to fund his work until the research project was completed in 2007. In 2009, Boeing paid the UK government to licence the technology so that they could develop it for the US military, but their progress is still being kept under wraps.

What’s next

Guido Fetta CEO of Cannae Inc, and inventor of the Cannae Drive (related to the EmDrive) plans to settle the argument about reactionless space drives for once and for all by sending one into space to prove that it really generates thrust without exhaust. Even if mainstream scientists say this is impossible. No launch date has yet been announced, but 2017 seems likely. “Once demonstrated on orbit, Theseus will offer our thruster platforms to the satellite marketplace,” says the optimistic conclusion on their website.

There is competition. In addition to the Chinese, and Shawyer himself, a lively open-source community of EmDrive enthusiasts has sprung up. They’re building their own drives, and the online discussion on nasaspaceflight.com now runs to many hundreds of pages of informed technical comment.

A good and easily-proven theory would certainly make it easier for the scientific community to take claims of propellantless drives more seriously. But what really matters is whether Cannae can really get the drive to work in space. The payoff would be impressive but it would be a success against long odds.