In a paper posted in NASA’s Technical Reports Server – a public database containing aerospace documents created or funded by NASA – Burns explained that the helical engine consists of a helix-shaped particle accelerator, an apparatus that produces a beam of fast-moving, electrically charged particles.
Burns, an engineer for NASA’s Marshall Space Flight Center, said that this particle accelerator can propel a spacecraft even without propellant.
Space travel is extremely limited due to several challenges. For one, current spaceflight technologies cannot cover vast distances quickly. NASA’s Voyager and New Horizons spacecraft, for instance, will take tens of thousands of years to reach Alpha Centauri, the star nearest the solar system. Moreover, refueling in space is not an option at the moment, which means the distance that can be traveled is limited.
But the helical engine, according to Burns, could make space travel faster and fuel-free. The apparatus works by accelerating ions confined in a loop. The ions are driven at near the speed of light to produce thrust and then decelerated to keep the spacecraft moving forward. The engine, according to Burns, has no moving parts other than the ions moving in a vacuum line.
“This in-space engine could be used for long-term satellite station-keeping without refueling,” said Burns. “It could also propel spacecraft across interstellar distances, reaching close to the speed of light.”
While Burns admitted that the helical engine is a thought experiment and remains unproven, he is prepared for criticism and thinks that the attempt is nonetheless worthwhile.
“If someone says it doesn’t work, I’ll be the first to say, it was worth a shot,” said Burns, who funded the study himself. “It is very difficult to invent something that is new under the sun and actually works.”
Ion propulsion methods are not a new concept. In fact, NASA is actively developing ion propulsion technologies for use in future space missions. One such technology is the Hall thruster, an ionic plasma engine that uses a stream of ions to propel a spacecraft. Plasma is expelled to generate thrust, producing far greater speeds than are possible with chemical propulsion rockets.
A chemical propulsion rocket achieves a maximum speed of around 3.1 miles per second (miles/sec), while a Hall thruster can reach speeds of up to 25 miles/sec.
Moreover, while a Hall thruster isn’t exactly fuel-free, it still uses less fuel compared to its counterpart. It can reach 10 times the distance attainable by a chemical propulsion rocket using the same amount of fuel. (Related: What to do with human waste in space? Convert it into rocket fuel!)
A Hall thruster, however, also has limitations. For one, it produces only a very small amount of thrust, which means that it needs to operate for a long time to provide the same level of acceleration as a chemical rocket.
But NASA scientists, together with the Air Force and researchers from the University of Michigan, hope to resolve these issues with a new type of Hall thruster called the X3 thruster. One improvement in this thruster, for instance, involves using multiple channels of plasma rather than just one.
Results from recent tests were favorable, with the X3 thruster generating 5.4 Newtons of thrust – the highest amount of thrust produced by any ionic plasma thruster to date. Once the technology is fully developed, the researchers said it may bring humans to Mars within the next 20 years.
Learn more about the science behind space travel at Space.news.