he first prototype of an aircraft intended to revolutionise travel and shatter speed records was destroyed during its maiden flight on Saturday after a booster rocked carrying it aloft veered out of control and tumbled from the sky,.

US space scientists were forced to destroy the unmanned X-43A prototype in mid-air just minutes before the plane was due to fire the oxygen-scooping 'Scramjet' engine designed to drive it at seven times the speed of sound. NASA cameras abroad two F-18 chase planes showed the Pegasus rocket careening off course and falling out of control from the sky before controllers triggered on-board explosives to destroy it over the Pacific Ocean at about 1:45 pm (8.45 pm, GMT). Pieces of the booster rocket and the small, black X-43A prototype, part of NASA's 'Hyper-X' programme, fell into the sea.

Dejected NASA scientists said they would form a "mishap investigation team" to determine what went wrong but vowed that the $ 185 million programme that they have billed as the future of aviation would go on.

"We're obviously disappointed at this but we're going to find out what happened, fit it and fly again." Hyper-X programme manager vince Rausch said. "We didn't think this was a slam dunk. There was some risk that this would happen and that risk wasn't zero."

Rausch said he could not speculate on how long it would take to investigate the failure or when the next test flight would be scheduled.

The X43-A was making the first of three scheduled test flights in the Hyper-X programme, which NASA has said will ultimately making space travel routine and pave the way for cross-country commercial flights in 30 minutes.

The scientists - who have called the programme an aviation breakthrough as historic as the Wright Brothers first flight - said they had no immediate information on what caused the failure, though they said it appeared to be the booster rocket, and not the X43-A itself or its hypersonic engine, that was at fault.

"There's a reason we have three of these (prototypes)," NASA spokesman Fred Johnson said. "It's an experimental flight test. If we knew the outcome we wouldn't be learning anything."

The X43-A and its Pegasus booster were carried to 24,000 feet (8,000 metres) by a B-52 bomber that left Edwards Air Force Base in the California desert at about 12:30pm and the mission appeared to be going smoothly as the small black plane and its booster detached.

The booster rocket was intended to accelerate the X43-A to Mach 7 speeds at about 100,000 feet (30,800 metres) before the prototype detached and operated for a few seconds at that speed, setting a speed record.The booster veered out of control before that could happen.

Scientists said the hypersonic engine - which took engineers some 40 years to create - would revolutionise space travel by obtaining its oxygen fuel from the air. The engine combines the oxygen with hydrogen to power the aircraft. This would avoid the need for it to carry its own oxygen supply, a weight savings that would allow it to fly greater distances or carry heavier payloads. Currently the fastest 'Air breathing' jet is the SR-71 Blackbird, which flies at Mach 3, or three times the speed of sound. The Scramjet would ultimately be designed to reach Mach 10 speeds.

Scientists said the 'Scramjet' engine could also be employed in military applications, powering a jet too fast for an adversary to shoot down.