NASA has aborted an attempt to set a new speed record for an aircraft, blowing up a rocket that was to help launch an unmanned X-43A jet.
The Pegasus booster rocket was ordered destroyed seconds after being released from the belly of a B-52 after it went out of control.
NASA had hoped the X-43A would reach speeds approaching Mach 7 during its fleeting flight, besting the Mach 6.7 record set by the rocket-powered X-15 in 1967.
The B-52 carried it and the Pegasus rocket over the Pacific Ocean, where the rocket was ignited.
It was to have boosted the experimental plane to approximately 100,000 feet altitude before releasing it.
The X-43A was designed to then fire its specialised engine - called a scramjet - and fly under its own power for 10 seconds, covering about 17 miles before coasting to an impact in the water.
"The Pegasus went out of control, it appeared parts were breaking off of it," said Mr Alan Brown, a NASA spokesman.
The experimental jet was presumed destroyed in the explosion, which occurred at about 45,000 feet above the Pacific.
PA