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Every so often there is a buzz that someone has made a stunning break through in the Physical Sciences and achieve something wondrous. Antigravity, a space warp, cold fusion, action at a distance or some such. There are persistent rumors that people who know better than us are seriously researching exotic physics and indeed physics is become so bizarre that it would take a really arrogant person (such as the English scientists who declared the end of Physics after Newton had enunciated his laws of motion) to say any of these things are really truly impossible. There is a sort of suspicion that if we can’t go through the problem maybe we can go round it.
The latest example of this is the so called Emdrive developed initially by a small English company SPR (Satellite Propulsion research) Ltd The developer Roger Shawyer has good credentials and does not seem a lunatic but that has not stopped a lot of people some of them very well qualified themselves responding to a recent article in New Scientist with a mixture of scorn outrage and the scientific version of frothing at the mouth. This is because the claim if true will transform space travel and given that the Chinese have taken up the idea ahead of the rest of the space faring world it will see the Chinese with a healthy lead in a radical new development.
The Chinese team has purchased rights to part of the process and claims to have verified the theory and made progress with its practical application since June 2007. The team headed by Professor Yuan at Northwestern Polytechnical University (NPU) in Xi’an is building a thruster based on Shawyer’s theories scheduled to be completed by end of this year.
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. One can’t help thinking that it sounds too good to be true.

The developer Roger Shawyer, 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.
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. 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.

For more go to http://www.newscientist.com/article/mg19125681.400 and also www.wired.com/dangerroom/2008/09/chinese-buildin/