Each action corresponds to an equal and opposite reaction: third law of dynamics. It is the principle on which space rockets are based, which burn propellant in one direction to go in the opposite direction.
However, a NASA engineer believes he can take us to the stars without any propellant, thanks to a special helical motor. An engine that would be the basis of all the spaceships of the future.
Drawn by David Burns of the Marshall Space Flight Center in Alabama, the "helical engine" exploits the effects of mass alteration that occur at speeds close to that of light. Burns has published a descriptive paper of the concept on NASA's technical report server.
Needless to say, his work met the skepticism of part of his colleagues, but Burns believes that the concept is valid, and will be the forerunner of many space engines of the future. "If anyone tries that it doesn't work, I will have no problem changing my mind, but this option is also worth exploring," he says.
How does the helical motor work?
To understand a little the principle of the helically shaped motor made by Burns, try to imagine a box on a surface that has no friction. Inside the box there is a bar around which a ring slides. If an impulse inside the box gives a push to the ring, it will slide forward while the box goes in the opposite direction. Once you touch the edge of the box, the ring will go back, and the box will, too, reversing its direction. Under normal conditions the third law of dynamics produces an oscillation from right to left of the ring.
But what would happen, Burns wonders, if the mass of the ring was larger when it goes in one direction and then smaller when it returns in the opposite direction? In fact, the action would be greater than the reaction, the third law of dynamics would be bypassed and the box would move forward.
How can that ring change its mass?
This is not "prohibited" by physics. Einstein's theory of special relativity says that an object acquires mass as it approaches the speed of light (an effect that can be demonstrated to a small extent by current particle accelerators).
In fact, if we replace the ring in the box with a particle accelerator, we have obtained the result. The ions inside the ring would be brought to speeds close to those of light (increasing mass) when going in one direction and decelerating them (decreasing mass) when going in the other.
It can be done even better
Burns thinks that the system would have even more efficiency if you did without a stick and ring, and replaced everything with a single propeller-shaped particle accelerator, capable of making the particles perform both lateral and longitudinal movement: a helical movement, precisely.
What about the box?
A rather large one would be needed by eye and cross. It is no coincidence that the sizes of this engine are in the order of 200 meters in length and 12 in diameter. The energy required is also enormous, according to the calculations: 165 megawatts of energy are needed to generate the thrust equal to 1 newton (this is the force we use to press a key on the keyboard).
For this reason, the engine can only work in a "large frictionless box" (or almost): the outer space.
"With the right amount of time and energy, this engine could reach 99% the speed of light in space," says Burns.
An electromagnetic motor with thrusters, but without propellant
At the end of the 70s, Robert Cook, an American inventor, patented the design of an engine capable, according to him, of converting centrifugal force into linear motion.
30 years later, in the early 2000s, the English inventor Roger Shawyer proposed the EM drive, which he said was capable of converting microwave push.
In January 2017, a magnetic motor developed in NASA's Eagleworks Laboratory seemed to have hit the target, but more detailed tests revealed a design error in these magnetic propulsion engines. Phenomenon also known as "how to melt an engine".
Neither concept has yet been successfully tested: both are judged impossible for their violation of a key physics law, the law of conservation of angular momentum.
Martin Tajmar University of Technology Dresden, Germany, has tested the EM Drive (unsuccessfully) and believes that the helical motor will likely have the same problems.
"As I see it, no inertial propulsion system will ever work in space environments," he says.
The principle of this impossible engine respects special relativity, which makes it special, but "unfortunately there is always an action-reaction mechanism to consider".
Burns has worked on his own, and admits that the engine model is rather inefficient. However, it is without prejudice to the principle, and believes that there is potential for improvement.
"I know the risks associated with presenting technologies such as cold fusion or EM Drive," He says. "I know my reputation will be debated, but you have to take the risk if you want to invent something new".
The impression is that of being in front of very interesting ideas of an extremely embryonic project. All ideas are present, but the whole appears premature.