What is an EmDrive?
The EmDrive, short for Electromagnetic Drive, is a radical new propulsion system with a pretty simple design that was first proposed nearly 20 years ago.
It is a metal cone with microwaves that bounce around inside its walls. When the microwaves hit the walls of the device, it produces thrust.
The kicker is that, unlike a rocket, the cone is totally closed off at both ends.
That's right, no exhaust, no steam, nothing "pushes" out of it, yet it seems to create thrust.
A traditional rocket engine goes forward by burning fuel and pushing the hot exhaust out the back. That's how airplanes, space ships, and almost anything that flies gets its thrust.
How does it work?
The truth is, no one seems to know. Not even the researchers at NASA, the American space agency who studied the drive, can give an explanation.
Many scientists expected the EmDrive to flop after NASA got involved. But the opposite happened.
NASA's own Advanced Propulsion Physics Laboratory, nicknamed Eagleworks, built a version of the EmDrive and tested it in a vacuum. The team put their experiment through a year-long peer reviewed study, and published their findings last week.
They published a paper saying it works. But the ‘how' is still a mystery.
Doesn't this break the laws of physics?
Sir Isaac Newton proposed three laws of motion which has held up for the past few centuries.
His third law says, "Every action must have an equal and opposite reaction."
The EmDrive seems to go against our current understanding of how things move, seeming to "break" Newton's third law.
In the case of the EmDrive, there seems to still be thrust, but no "action" that seems to cause it.
Another quirky thing about the EmDrive was discovered when NASA scientists fired a laser into it while it was turned on. They said that some of the lasers travelled faster than the speed of light, again something that shouldn't be possible.
What does this mean for space travel?
Without heavy and inefficient rocket fuel burdening a spaceship, going from point A to B would be much faster.
For example, a trip to Mars would take just 70 days instead, of 18 to 20 months with a conventional rocket ship.
A journey to our nearest star, Alpha Centauri, with something like NASA's Space Shuttle Discovery would take 165,000 years.
With the EmDrive, researchers at NASA say we could get there in a more reasonable 92 years.
Is there another explanation for the thrust that NASA observed?
We asked Matteo Cantiello, a specialist in astrophysics at the Kavli Institute for Theoretical Physics at the University of California at Santa Barbara to look at the published paper. He has another theory about what's going on.
"Experiments that seem to violate fundamental laws of physics turned to be almost always wrong in the end. And this seems to be no exception."
Cantiello, who is also chief scientist at Authorea, thinks that heat from the device is causing the perceived thrust.
"The likely reason for the spurious observed trust is related to unaccounted thermal expansion of the device."
But he remains cautiously hopeful.
"This is a case of 'Extraordinary claims requires extraordinary evidence'. And the evidence is lacking here, but hopefully more experiments will follow. I would love to be proven wrong, but at this time my position is that there is no new physics here. Sorry, I understand if this is not as exciting," he said, quoting renowned astronomer and astrophysicist Carl Sagan.
Who plans to use this technology next?
A US-based company, Theseus Space Inc., is planning to outfit tiny satellites called CubeSats with a similar propulsion system called Cannae.
"Theseus is going to be launching a demo CubeSat which will use Cannae thruster technology to maintain an orbit below a 150 mile altitude. This CubeSat will maintain its extreme LEO altitude for a minimum duration of 6 months," according to the company's website.
Known as a 'CubeSat', these small and lightweight satellites are expected to be the first real-world application for EmDrive's technology. (Cannae)
Will this technology blur the lines between science and fiction, or will researchers discover a more down-to-Earth explanation for this seemingly impossible device?