EM Drive Tested By NASA: Lets Not Get Too Excited Just Yet

A big news story has been making the rounds about a new and potentially game changing space propulsion technology, which was recently tested by NASA scientists in a vacuum chamber at the Manned Space Flight Center in Houston Texas.  The system, called the EM Drive, is based on microwaves bouncing around a specially shaped cavity.  These aledgedly create thrust, thus making it possible for the EM drive to be used as a propulsion system, if attached to a spacecraft.

What  makes the EM drive so much different than any previous propulsion technology is that it does so without expelling any propellant.  All existing rocket engines use some kind of material, known as reaction mass, in order to produce thrust.  Even highly efficient ion engines require a gas of some sort to be used as the reactionary mass.  The need for propellant is a major limiting factor in spaceflight.  It means that propellant must be launched with the spacecraft, often constituting a large percentage of the spacecraft’s mass.  It also limits the duration of the spaceflight.  Eventually the propellant runs out.  However, the EM drive uses only energy, which can be provided almost without limits by solar panels or a nuclear power source, which could provide energy for decades.

The only problem with this is that the whole concept seems to violate the law of conservation of momentum.  Our current understanding of physics would seem to indicate that this is impossible.  You can’t add momentum to something without pushing off of something else.  Every action has an equal and opposite reaction, and that’s why rockets need to shoot propellant in one direction to go in the other.

Via IO9:

New Test Suggests NASA’s “Impossible” EM Drive Will Work In Space
[T]he EM Drive’s thrust was due to the Quantum Vacuum (the quantum state with the lowest possible energy) behaving like propellant ions behave in a MagnetoHydroDynamics drive (a method electrifying propellant and then directing it with magnetic fields to push a spacecraft in the opposite direction) for spacecraft propulsion.
Last year, NASA’s advanced propulsion research wing made headlines by announcing the successful test of a physics-defying electromagnetic drive, or EM drive. Now, this futuristic engine, which could in theory propel objects to near-relativistic speeds, has been shown to work inside a space-like vacuum.

NASA Eagleworks made the announcement quite unassumingly via NASASpaceFlight.com. There’s also a major discussion going on about the engine and the physics that drives it at the site’s forum.

The EM drive is controversial in that it appears to violate conventional physics and the law of conservation of momentum; the engine, invented by British scientist Roger Sawyer, converts electric power to thrust without the need for any propellant by bouncing microwaves within a closed container. So, with no expulsion of propellant, there’s nothing to balance the change in the spacecraft’s momentum during acceleration. Hence the skepticism. But as stated by NASA Eagleworks scientist Harold White:

The trouble with this theory, however, is that it might not work in a closed vacuum. After last year’s tests of the engine, which weren’t performed in a vacuum, skeptics argued that the measured thrust was attributable to environmental conditions external to the drive, such as natural thermal convection currents arising from microwave heating.

The recent experiment, however, addressed this concern head-on, while also demonstrating the engine’s potential to work in space. (Image: NASA Eagleworks.)

For those who champion the EM drive, the new experiment is certainly a big step toward proving it can actually work. However, it’s only one step, and there are many that will need to be taken.

The fact that it seems to violate a basic law of physics does not mean that it is necessarily impossible. In science, nothing, not even the most well established theories are ever considered absolutely impossible to be wrong.  We do know that Newtonian physics has its limits and that relativity and quantum mechanics allow things to happen that regular Newtonian physics would not predict.  We also don’t necessarily have a full understanding of all that can happen as a result of quantum forces.

None the less, a claim this extraordinary requires extraordinary proof.  No experiment, no matter how apparently well designed and documented, offers enough evidence to come to the conclusion that something as amazing as the EM drive actually works.  What will be needed is for the experimental results to be replicated, by different teams, under different conditions and different scales and for the experimental setups to all be thoroughly examined to rule out any systematic errors or confounding factors.

But there is something more fundamentally wrong with this:

In the world of serious science, it’s never good enough to just provide a claim that an experiment confirms a hypothesis.  It’s never enough to just provide one basic measure of data.  The experiment and the results need to be thoroughly and properly documented and the data provided in full for examination and to allow the basic methodology to be examined.  This should be done in a peer reviewed journal.

Of course, peer review is not infallible.  There can still be errors, and it definitely can’t catch all the problems a study may have.  Regardless of how good the peer review is, something this earth shattering will still need confirmation.  But peer review is, none the less, the minimum standard to take scientific data seriously.  If it’s not peer reviewed, it’s about as reliable as something that your cousin’s friend’s neighbor says they remember overhearing at a cocktail party.  In other words, not very.

Not only was this data not formally reported in a peer reviewed study, it was reported in about the most informal and unverifiable way imaginable.  The data, not only being incomplete, but being posted on an internet form.  If there is a worse source of scientific data than a press release, this is it.

Personally, I would love to find out that the EM drive does work as claimed.  It would mean a new era in space exploration and would be one of the most revolutionary developments in space exploration since the first successful satellite launches.  However, wanting it to be true does not make it true.   If we can get a formal, peer reviewed paper on it, we can at least begin to consider the possibilities.  At minimum, it would give some solid data.  Until then, this really is little more than some unsubstantiated claims and speculation.