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Leaked NASA Paper Suggests The 'Impossible' EM Drive Really Does Work (sciencealert.com)
A source close to NASA Eagleworks has leaked the test results of the 'impossible' EM Drive. While it's important to note that the results that have been leaked haven't been published in an academic journal, they do suggest that the system works and is capable of generating force of 1.2 millinewtons per kilowatt in a vacuum. ScienceAlert reports: The paper concludes that, after error measurements have been accounted for, the EM Drive generates force of 1.2 millinewtons per kilowatt in a vacuum. That's not an insignificant amount -- to put it into perspective, the super-powerful Hall thruster generates force of 60 millinewtons per kilowatt, an order of magnitude more than the EM Drive. But the Hall thruster uses fuel and requires a spacecraft to carry heavy propellants, and that extra weight could offset the higher thrust, the NASA Eagleworks team conclude in the paper. Light sails on the other hand, which are currently the most popular form of zero-propellant propulsion, use beams of sunlight to propel them forward rather than fuel. And they only generate force up to 6.67 micronewtons per kilowatt - two orders of magnitude less than NASA's EM Drive, says the paper. The NASA Eagleworks team measured the EM Drive's force using a low thrust pendulum at the Johnson Space Centre, and the tests were performed at 40, 60, and 80 watts. They were looking for any sign that the thrust could be a result of another anomaly in the system, but for now, that doesn't appear to be the case. "The test campaign included a null thrust test effort to identify any mundane sources of impulsive thrust, however none were identified," the team, led by Harold White, concluded in the paper. "Thrust data from forward, reverse, and null suggests that the system is consistently performing with a thrust to power ratio of 1.2 +/- 0.1 millinewtons per kilowatt." But the team does acknowledge that more research is needed to eliminate the possibility that thermal expansion could be somehow skewing the results. They also make it clear that this testing wasn't designed to optimize the thrust of the EM Drive, but simply to test whether it worked, so further tweaking could make the propulsion system more efficient and powerful.
Ran some numbers. Assuming the power generator and thruster itself has zero mass (obviously not, but it lets us set an upper limit), the energy available in 1kg of U235, at 1.2 millinewtons/kw, would accelerate that 1 kg mass to about 0.35 C, over the course of about 1000 days.
Add in mass of ship, generators and thrusters and you're looking at considerably less acceleration and top speed, but if this thing works at all (a big IF, granted), manned starships are just within the range of possibility. It'd still be a multi-year (probably multi-decade) trip, but hey.
Here's a link to the NASA paper on the apparently successful test: https://drive.google.com/file/...
And here is a presentation by the technology's inventor, Roger Shawyer https://vimeo.com/channels/Emd...
Warning: Shawyer may well be brilliant, but he is the Anti-Musk in terms of his presenting and motivational skills. This guy could seriously announce a working warp drive in a way that would make people walk out of the presentation half way through. If he has funding problems, he needs to get someone else to present his technology and business case for him.
Where are we going and why are we in a handbasket?
If it has mass, how can it travel at c?
It doesn't, but not for that reason.
A simplified answer is that because it travels at c, spacetime doesn't apply to it, only to what it passes through. c is an asymptote, which other particles can only approach. Photons live inside the asymptote, and are not subject to the standard rules for what occurs.
In E=mc^2 (or the general expanded version), "c" is a constant for distance divided by time. As Einstein discovered, time itself is suspect - it varies. Which is fine as long as you only approach c, because distance compensates exactly. But when time no longer approaches zero but is zero, "c" becomes infinity divided by zero, which is meaningless. A single photon is then everywhere, anywhen, which doesn't match our observations.
We can only assign a photon "mass" through equivalence - what mass changes occur when a photon is created or destroyed. While[*] it exists, it's meaningless to assign it mass, but it's meaningful to assign it a mass change potential, or momentum.
[*]: Also a meaningless term for a photon, as a photon's life span is instantaneous or infinite, never anything in-between. Any "while" only affects the surroundings, not the photon itself. It laughs at clocks.
If you have enough delta v you can fly on a hyperbolic orbit, which can be as fast as you like. That dv can be delivered all at once, at the beginning (and hopefully the end) like we do it now, or it can be delivered continuously, like we'd do with this engine.
If Eagleworks has conclusive data that the EmDrive does indeed work, then there should be a Manhattan Project level of funding pushed towards it. It would change everything.