For years, space geeks have been intrigued by the idea of propulsion systems that don’t need propellant – and now one of the best-known concepts, known as the EmDrive, is getting a serious once-over.
The EmDrive, short for electromagnetic drive, could be revolutionary for spaceflight if it works. Spaceships could dispense with the mass of rocket fuel, and because the velocity builds up progressively, trips to Mars and beyond would be much faster and simpler.
The concept involves bouncing microwaves around a closed cavity that’s shaped like a cone. The shape supposedly funnels the microwaves to generate forward thrust.
The problem is, Newton’s Third Law of Motion says it shouldn’t work that way. If there’s an equal and opposite reaction for every action, the skeptics say the EmDrive – and the spaceship it’s bolted onto – should stay perfectly still. The effect has been compared to trying to push your car down the road by sitting in the driver’s seat and pushing against the steering wheel.
For more than 15 years, researchers associated with NASA’s Johnson Space Center have been trying to determine whether the “impossible” effect is actually possible, and more recently Chinese researchers have gotten into the act.
Proponents of the EmDrive say their experiments show a measurable effect, but most physicists have pooh-poohed the results. The back-and-forth is reminiscent of the debate over “faster-than-light neutrinos” in 2011 – a debate that was settled when researchers traced their readings to a loose fiber-optic cable.
A turning point for the EmDrive came last month, when a peer-reviewed publication called the AIAA Journal of Propulsion and Power accepted a paper on the NASA team’s latest findings. The effect was measured at 1.2 millinewtons per kilowatt. That’s small compared to chemical rocket propulsion, but significant compared to, say, light sail propulsion.
That paper got the folks at the Tau Zero Foundation interested. Today, Tau Zero’s founding architect, Marc Millis, assessed the findings with the aid of other propulsion experts from around the world.
Their verdict? It’s complicated, but they say the research merits further study.
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http://www.isn-news.net/2017/01/impossible-emdrive-thruster-attracts.html
