More science, a little less hype.

http://technology.newscientist.com/article/mg19125681.400

If true, it would be really, really innovative.

That's strange, the link fails but I can go there from another article.

B

Here's an excerpt:

The device that has sparked their interest is an engine that generates thrust purely from electromagnetic radiation - microwaves to be precise - by exploiting the strange properties of relativity. It has no moving parts, and releases no exhaust or noxious emissions. Potentially, it could pack the punch of a rocket in a box the size of a suitcase. It could one day replace the engines on almost any spacecraft. More advanced versions might allow cars to lift from the ground and hover. It could even lead to aircraft that will not need wings at all. I can't help thinking that it sounds too good to be true.

When I meet Shawyer, he turns out to be reassuringly normal. His credentials are certainly impressive. He worked his way up through the aerospace industry, designing and building navigation and communications equipment for military and commercial satellites, before becoming a senior aerospace engineer at Matra Marconi Space (later part of EADS Astrium) in Portsmouth, near where he now lives. He was also a consultant to the Galileo project, Europe's satellite navigation system, which engineers are now testing in orbit and for which he negotiated the use of the radio frequencies it needed.

Dangerous idea

With that pedigree, you'd imagine Shawyer would be someone the space industry would have listened to. Far from it. While at Astrium, Shawyer proposed that the company develop his idea. "I was told in no uncertain terms to drop it," he says. "This came from the very top."

What Shawyer had in mind was a replacement for the small thrusters conventional satellites use to stay in orbit. The fuel they need makes up about half their launch weight, and also limits a satellite's life: once it runs out, the vehicle drifts out of position and must be replaced. Shawyer's engine, by contrast, would be propelled by microwaves generated from solar energy. The photovoltaic cells would eliminate the fuel, and with the launch weight halved, satellite manufacturers could send up two craft for the price of one, so you would only need half as many launches.

So why the problem? Shawyer argues that for companies investing billions in rockets and launch sites, a new technology that leads to fewer launches and longer-lasting satellites has little commercial appeal. By the same token, a company that offers more for less usually wins in the end, so Shawyer's idea may have been seen as too speculative. Whatever the reason, in 2000, he resigned to go it alone.

Surprisingly, Shawyer's disruptive technology rests on an idea that goes back more than a century. In 1871 the physicist James Clerk Maxwell worked out that light should exert a force on any surface it hits, like the wind on a sail. This so-called radiation pressure is extremely weak, though. Last year, a group called The Planetary Society attempted to launch a solar sail called Cosmos 1 into orbit. The sail had a surface area of about 600 square metres. Despite this large area, about the size of two tennis courts, its developers calculated that sunlight striking it would produce a force of 3 millinewtons, barely enough to lift a feather on the surface of the Earth. Still, it would be enough to accelerate a craft in the weightlessness of space, though unfortunately the sail was lost after launch. NASA is also interested in solar sails, but has never launched one. Perhaps that shouldn't be a surprise, as a few millinewtons isn't enough for serious work in space.

But what if you could amplify the effect? That's exactly the idea that Shawyer stumbled on in the 1970s while working for a British military technology company called Sperry Gyroscope. Shawyer's expertise is in microwaves, and when he was asked to come up with a gyroscopic device for a guidance system he instead came up with the idea for an electromagnetic engine. He even unearthed a 1950s paper by Alex Cullen, an electrical engineer at University College London, describing how electromagnetic energy might create a force. "It came to nothing at the time, but the idea stuck in my head," he says.

In his workshop, Shawyer explains how this led him to a way of producing thrust. For years he has explored ways to confine microwaves inside waveguides, hollow tubes that trap radiation and direct it along their length. Take a standard copper waveguide and close off both ends. Now create microwaves using a magnetron, a device found in every microwave oven. If you inject these microwaves into the cavity, the microwaves will bounce from one end of the cavity to the other. According to the principles outlined by Maxwell, this will produce a tiny force on the end walls. Now carefully match the size of the cavity to the wavelength of the microwaves and you create a chamber in which the microwaves resonate, allowing it to store large amounts of energy.