New space drive

[UtwigMU]

http://www.wired.co.uk/news/archive/2014-07/31/nasa-validates-impossible-space-drive

British scientist Roger Shawyer has been trying to interest people in his EmDrive for some years through his company SPR Ltd. Shawyer claims the EmDrive converts electric power into thrust, without the need for any propellant by bouncing microwaves around in a closed container. He has built a number of demonstration systems, but critics reject his relativity-based theory and insist that, according to the law of conservation of momentum, it cannot work.

Doc, can you shed what you think of this?

[Jammrock]

It's been validated a couple of times now so ... I would say it works. Whether we know for certain why it works is a different question.

[Dr Mordrid]

Their fellow scientists at NASA are very skeptical (a forum where many of them hang out is abuzz with it.) One big question is their null device producing "thrust," and there are other issues. Atmospheric effects were not removed from the test chamber, the effects of outgassing and mass loss were not accounted for and the AIAA paper in question only has two references, one to the creator's website and one to the Chinese test.

Even if the miniscule thrust levels are real you can get much more than that with a solar sail of similar mass, and Hall Effect ion thrusters have been tested to 3 full Newtons. Granted HET's require a propellant (usually xenon etc.), but we're talking tens or a hundred kilograms for a major unmanned mission massing several tonnes..