WASHINGTON: In what could be a game changer in space exploration, Nasa has successfully tested a "microwave thruster system" that requires no propellant to generate thrust.

The engine appears to produce propulsion through electricity and nothing else.

In a test paper, Nasa scientists said they recorded about 30-50 micro-Newtons (mN) of thrust from an electrical propulsion test article, harnessing subatomic quantum particles.

Testing was performed on a low-thrust torsion pendulum that is capable of detecting force at a single-digit micronewton level, within a stainless steel vacuum chamber with the door closed but at ambient atmospheric pressure.

This means that Nasa may be able to create an inexpensive low-thrust, long-term technology with virtually no cost.

The discovery can also reduce the cost of maintaining orbital stability of satellites and interstellar travel.

"This unique electric propulsion device is producing a force not attributable to any electromagnetic phenomenon, and is potentially interacting with quantum vacuum virtual plasma," Nasa said in the test paper.

The U.S. space agency now plan to run further tests to validate its findings.