Virgin Galactic 'ignored' space safety warnings: Expert

Los Angeles: Virgin Galactic "ignored" repeated warnings in the years leading up to the deadly crash of its spacecraft in California, a rocket science safety expert has said, as investigators hunted for clues to the accident.

After a second full day of investigation, the acting chairman of the National Transportation Safety Board told reporters yesterday that a lock-unlock lever on the spaceship had been moved prematurely, but emphasised that the cause of the crash was still unknown.

Carolynne Campbell, a rocket propulsion expert with the Netherlands-based International Association for the Advancement of Space Safety, said she could not speculate on the cause of Friday's crash without "all the data."

However, she said multiple warnings about the spacecraft's motor and the fuel used to power it had been issued to Virgin since 2007, when three engineers died testing a rocket on the ground.

"Based on the work we've done, including me writing a paper on the handling of nitrous oxide, we were concerned about what was going on at Virgin Galactic," she told AFP.

"I sent copies of the paper to various people at Virgin Galactic in 2009, and they were ignored."

Campbell said she outlined concerns to Virgin Galactic in a subsequent telephone conversation, but her warning again went unheeded.

"I warned them... That the rocket motor was potentially dangerous," she said.

Campbell's warnings related to nitrous oxide, reportedly used as a fuel component in the doomed craft along with a new substance derived from nylon plastic grains.

After the major setback to British tycoon Richard Branson's plans, Virgin Galactic released a statement late Sunday in which it said it was "dedicated to opening the space frontier, while keeping safety as our 'North Star.'

"This has guided every decision we have made over the past decade, and any suggestion to the contrary is categorically untrue," it said.