The announcement is sure to be a disappointment to British engine designers who have said for years that it would be possible to steal a march on the US by building air-powered engines that would be able to drive aircraft at high speeds through the thin upper atmosphere.
The Nasa Hyper-X project is worth $33.4m (pounds 20.9m) over the next four years, and intends to produce four of the vehicles, each able to travel at more than Mach 5 (five times the speed of sound) - defined as "hypersonic". The vehicles could be used either as high-speed aircraft or as reusable space launchers.
Unlike a rocket, which carries its own oxygen fuel for combustion, the Hyper-X will scoop up oxygen from the atmosphere, flying at up to 100,000ft. The lack of extra fuel load should mean that it can carry more equipment, and have a longer range than an equivalent rocket-powered system. It will almost certainly use a "ramjet" principle, in which the forward speed of the vehicle compresses the incoming stream of air, which is then burned with a jet fuel. In conventional jet engines, it is the movement of the fan blades which compress the air.
Announcing the award of the Hyper-X contract to a company in Tennessee, the Nasa administrator Daniel Goldin said "We're embarking on an ambitious series of Hyper-X flights to expand the boundaries of aeronautics and develop new technologies for space access."
But the announcement is a further disappointment to independent British designers such as Alan Bond and David Ashford, who have submitted numerous designs for high-speed air-breathing vehicles. One of Mr Bond's ideas, called Hotol, was examined closely by Rolls-Royce but eventually turned down over funding.
Both Mr Bond and Mr Ashford have been critical of the British government's refusal to inject any funding into their work, as such cash could act as a "seedcorn" which would then make them eligible for larger funding from the European Space Agency. While both designers accept that Britain does not have the resources alone to design and build such radically new vehicles, they have always maintained that Europe does.
Last year, when Nasa indicated that it might begin developing a Hyper- X type system, Mr Bond commented "We have had a world lead in this type of engine design since the Eighties. I've always believed it was the answer to cheap access to space, but now it looks like America will develop it."
Nasa, meanwhile, is taking advantage of its lead. "We are ready to prove this technology - to be the first to fly an air-breathing vehicle at hypersonic speeds," Vince Rausch, the Hyper-X project manager at Nasa, said.
Mr Bond has designed a vehicle called "Skylon" which would have two huge air-breathing engines, one on each wing, and travel at five times the speed of sound at a height of up to 85,000ft. It would be able to carry up to 60 passengers. He envisaged it as a possible rival to long-haul aircraft, or to the Space Shuttle.Reuse content