Nasa finally publishes controversial fuel free 'impossible drive' paper - but still can't explain how it works
The radical concept of a fuel-free ‘impossible’ engine has now gained far more credibility.
In recent weeks, a leaked version of the paper stirred up controversy as it appeared to show that scientists had created a working EmDrive prototype.
Now, the findings have officially been peer-reviewed and published.
It’s said that the EmDrive could get humans to Mars in just 10 weeks, but experts have long argued that idea cannot be brought to life as the engine defies the fundamental laws of physics.
The paper, now published in the AIAA’s Journal of Propulsion and Power, describes a series of successful tests carried out by scientists at NASA's Eagleworks Laboratories.
Its publication means it has now been reviewed by scientists independent to the study.
Essentially, the EmDrive generates thrust by harnessing particles of light and bouncing microwaves around inside a closed chamber, shaped like a cone.
The movement generates thrust at the slim end of the cone, which drives the engine forward.
But as it has no fuel to eject, this system goes against Newton’s Third Law, which states that for every action, there is an equal and opposite reaction.
In the new study, which tested if the device could operate in a vacuum, the researchers found that 'thrust data from forward, reverse, and null suggested that the system was consistently performing at 1.2±0.1 mN/kW1.2±0.1 mN/kW, which was very close to the average impulsive performance measured in air.'
The supporting physics model for these conditions, according to the researchers, could be a 'nonlocal hidden-variable theory, or pilot-wave theory for short' - an interpretation of quantum mechanics.
Some experts have claimed that there ‘may really be something there’ in the findings – but, the cause might be something entirely different than what’s been proposed.
Rather than the quantum vacuum theory which was initially cited in the leaked version to explain the findings, a phenomenon known as the ‘Mach effect’ could be to blame, according to Motherboard.
"The issue involved here is whether the experiment is seeing something real or not," - Jim Woodward, a physicist at California State-Fullerton, told Motherboard.
"I know Paul [March, one of the lead researchers] does clean work and to be honest, I suspect there may really be something here."
"But the result they’re seeing can’t actually be explained in terms of the theory they’re proposing. So the question is: what is causing it?"
The tests managed to generate powers of 1.2 millinewtons per kilowatt (mN/Kw), a fraction of the current state of the art Hall ion thruster, which can achieve a massive 60 mN/Kw
Researchers in the past have proposed both the quantum vacuum theory – which states that the microwaves are pushing off virtual particles in the cavity to generate thrust – and an explanation in which radiation pushes against the machine’s walls.
But according to Woodward, neither of these are likely to be correct, as they do not follow the laws of physics.
‘Can any disposition of microwaves inside the cavity produce thrust? There’s a simple answer to that question: No, it cannot,’ Woodward told Motherboard.
‘Conservation of momentum dictates that any purely electromagnetic system that is enclosed cannot produce thrust.
‘This is for both quantum theory and classical electrodynamics. It’s physically impossible.’
Instead, the physicist says the seemingly impossible nature of the EmDrive may be explained by the Mach effect without breaking the laws of physics.
By this effect, which Woodward first theorized in the 1990s, some of the force applied to an accelerating body of mass is stored as potential energy in its body rather than generating kinetic energy, according to Motherboard.
This causes fluctuations in the object’s resting mass, and this effect could be harnessed to create the type of thrust seen in the experiments.
But, tests to attempt to reproduce the results of the NASA study using the Mach effect theory would be necessary to confirm this.
It was subsequently published by NextBigFuture, and describes how early tests of the system in a vacuum, recreating the conditions of the engine if it were used in space.
The 'leaked' NASA paper
A research report, which has appeared online, describes a series of successful tests carried out at Nasa’s Johnson Space Center in Texas.
It outlines a experiments with a 'closed radio frequency cavity'.
The paper describes how early tests of the system in a vacuum, recreating the conditions of the engine if were used in space.
Engineers carried out controlled bursts at 40, 60 and 80 watts, reporting that the thrust achieved in a vacuum was similar to the performance achieved in air.
The tests managed to generate powers of 1.2 millinewtons per kilowatt (mN/Kw), a fraction of the current state of the art Hall thruster, which can achieve a massive 60 mN/Kw.
But the researchers say that the lack of fuel consumption could make up for the drop in power.
What is the EmDrive?
The concept of an EmDrive engine is relatively simple.
It provides thrust to a spacecraft by bouncing microwaves around in a closed container.
Solar energy provides the electricity to power the microwaves, which means that no propellant is needed.
The implications for this could be huge. For instance, current satellites could be half the size they are today without the need to carry fuel.
Humans could also travel further into space, generating their own propulsion on the way.
But when the concept was first proposed it was considered implausible because it went against the laws of physics.
Its allegedly fuel-free nature also means the drive may directly contradict the law of conservation of momentum.
It suggests it would produce a forward-facing force without an equal and opposite force acting in the other direction.