NASA has successfully tested a space engine called the Cannae Drive - one that the agency previously thought would never work because of its mechanics.

Inventor of the engine Guido Fetta, along with scientists from NASA's Eagleworks Laboratories presented a paper about the invention at a conference in Cleveland, Ohio, indicating they had achieved a small amount of thrust from the engine that contained microwaves instead of traditional fuels, according to The Verge.

The Cannae Drive works by bouncing microwaves around a small container and creating a different in radiation pressure, which exerted a thrust toward the larger end of the container. A similar engine called EmDrive, which was shown by Chinese and Argentine scientists at the Cleveland expo, works on a smaller scale.

Electricity is used to generate the microwaves in the EmDrive, and can be provided by solar energy. The engine doesn't need propellants, which allows the thrusters to work forever if it doesn't run into a hardware failure, Gizmodo reported.

Roger Shawyer, the inventor of the EmDrive, received criticism over the engine due to it theoretically not being to run. They still didn't believe him when he got it to work in 2009, producing 720 millinewton, enough to build a satellite thruster.

The Cannae Drive was also shown to work, but it was only able to produce a thrust of 30 to 50 micronewtons, which is much smaller, Gizmodo reported.

"Test results indicate that the RF resonant cavity thruster design, which is unique as an electric propulsion device, is producing a force that is not attributable to any classical electromagnetic phenomenon and therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma," the paper reads.

Fetta, who only has a Bachelor's Degree in Chemical Engineering and is running his company Cannae as a for-profit venture, says the engine still shows promise, The Verge reported.

If scientists are able to replicate and scale up the results, it could lead to the creation of an ultra-lightweight and fast spacecraft capable of sending humans to Mars in mere weeks, as well as to the closest star system outside our own in around 30 years.