Propulsion without Propellent

Flight Thrusters (Photo from

(Photo from

Article by Alex Repeta

While the seemingly impossible claims of recent developments made around sci-fi-esque engine, EmDrive, have taken many aback, it may be the future of astrophysics. Conventional engines have used fuel in the form of natural gases and oil to create chemical reactions in order to produce thrust. EmDrive brings about new technology that allows it to ditch the concept of gaining propulsion from fuel. The device is still clouded in mystery with even the brightest experts not able to fully comprehend how it works. The dramatic design’s departure from that of the stereotypical engine also leaves many skeptical of the invention.

What exactly is EmDrive? The concept of a fuelless electric engine was first proposed by a small UK company (Satellite Propulsion Research Ltd) back in 2001

( Simply put, the device converts electrical energy into microwaves to push itself forward. Inside the metal confines of the conical engine, energy is turned into electromagnetic waves that are capable of displacing atoms and molecules ( Imagine pushing against a car from the inside to make it move. While that may be a vague and rough metaphor of the engine, that’s how it is understood to work by many. According to a recent evaluation of the EmDrive by, SPR Ltd’s preliminary work and calculations proved that theoretically there was a way to directly convert electrical energy into thrust; however, the feasibility of creating the device was considered near-impossible, since the mechanics of the engine contradicted physics-giant Isaac Newton’s law of conservation of momentum. It states that within a closed system, both linear and angular momentum is preserved and stays constant (Williams). So in theory, no acceleration or thrust should be produced from a system that has no propellant. Current engines create thrust from burning fuel and causing explosive chemical reactions. Electromagnetic waves generated from the EmDrive as it stands it not only defies Newton’s law but various laws of relativity as well. The conundrum has left many scratching their heads with even NASA not fully understanding how it works. Unraveling the deeper concepts and secrets of EmDrive might require altering fundamental laws of physics and the creation of new ones.  

SPR Ltd.’s idea was later adopted by a team of Chinese researchers, who verified the propulsion theory behind it and built the first EmDrive in 2008 (Hesse). Although the thrust created by it was miniscule and no where near the calculated amount, it proved that the theory was valid. Since 2014, NASA has also began testing their own version in hopes of integrating the device into future galactic journeys (Hesse). So far, there have been no impressive results, but with each iteration of the device both efficiency and thrust have gone up. With NASA investing resources and time into the invention, it may be within our lifetime that this engine will actually be used to travel to Mars.

What makes even NASA excited about EmDrive is the incredible potential it possesses. Since EmDrive operates on the transmission of microwaves from electricity, it would eliminate the need for gaseous or liquid state fuel. This is would allow NASA’s spacecraft to travel faster and further, since the mass of conventional fuels wouldn’t weigh space vehicles down. As things now stand, astrophysicists can only compress the fuel so much and make the current engines only so efficient. With traditional technology, up to 80% of the mass of the spacecraft is fuel and most of that fuel is used to break out of Earth’s atmosphere. With the absence of the fuel mass mass in addition to the more powerful pound-for-pound engine, experts in the field (per the site speculated that EmDrive can reach a maximum velocity of 20% of the speed of light. Such speeds are not imaginable with the conventional propulsion setups for spacecraft. To the moon in a few hours, Mars in three months and Pluto in less than two years: galactic expansion and discovery could be easier than ever.

However, all this is speculation, and although working models have been produced, none have come close to matching the thrust emitted by a normal engine. Bringing this invention to the skies might be the task of the century, and if executed right, it could dramatically change the future.



Hesse, Brendan. Here’s the 411 on the EmDrive: the ‘physics-defying’ thruster even NASA is puzzled over. Digital Trends, 31Aug. 2016. Web. 7 Sep. 2016

The EmDrive. SPR LTd. n.d. Web. 7 Sep. 2016.

Williams, Matt. NASA’s EmDrive passes peer review, but don’t get your hopes up. Universe Today, 6 Sep. 2016. Web. 7 Sep. 2016.