Latest US space shuttle mishap prompts warning

CAPE CANAVERAL, Florida - Space shuttle Discovery's robotic arm was set to return to its Canadian manufacturer for repairs on Friday after the latest in a spate of accidents that prompted a stern call for caution at the Kennedy Space Center.

The March 4 mishap at the Florida spaceport, which left a crack in the robotic crane, triggered US space agency Nasa's first official investigation into the recent incidents, said Nasa spokeswoman Jessica Rye.

The accidents led to a two-hour work stoppage on Thursday to allow the entire 14,000-member space center work force to view safety videos and listen to a taped briefing by center director Jim Kennedy.

"The American people have entrusted us with significant assets," Kennedy said in the telecast.

"We understand that incidents may occur, but a major mishap could result in losing the confidence of the American people to execute our mission and derail Nasa's plans to complete the International Space Station and begin exploration of the moon, Mars and beyond," he said.

The accident is unrelated to Nasa's decision, announced on Tuesday, to delay Discovery's launch from May to July, said shuttle programme manager Wayne Hale.

Discovery's robotic crane was hit by a bucket-shaped work platform employees were using to clean up areas of the shuttle's payload bay. The cleanup was ordered after another accident on March 3, when a technician broke a work light.

Inspections showed a small crack in the lower portion of the shuttle's carbon composite robotic arm.

A six-metre section of the arm will be replaced by Spar Aerospace, which built the robotic crane for the Canadian Space Agency in partnership with Nasa.

While the damage to the arm is the only such incident to have sparked an official Nasa investigation so far, shuttle prime contractor United Space Alliance and subcontractors are looking into a series of incidents.

Workers accidentally started a small fire last week on the roof of the 160 metre tall building where the shuttle is attached to its fuel tank and booster rockets.

At the time, two fully assembled solid rocket shuttle boosters were in the building. If the fire had reached the boosters, it could have triggered an explosion which Kennedy said could have been "catastrophic."

Workers also forgot to lock the shuttle Endeavour's nose landing gear while the 75-ton spaceship was being transferred between floor jacks in its processing hangar. As the move began, the nose of the ship pitched forward.

"This incident could have resulted in major damage to the orbiter," Kennedy said.

Workers also over-pressurized a water line on the shuttle Atlantis and dropped a film canister on Endeavour, which damaged one of its ceramic heat tiles.

- REUTERS