A 9-foot, 70-pound metal bar mistakenly left in the shuttle Atlantis's engine room shifted and fell as the ship was rotated into the launch position, causing an unknown amount of damage.

While it was too early to say what impact, if any, the accident might have on Atlantis's Nov. 7 target launch date, engineers said the falling metal "access bar" came to rest near the intersection of several critical beams in the shuttle's engine compartment.Sources who requested anonymity said the bar fell more than 5 feet and at the very least, it appeared to have damaged foam insulation in the engine room, along with a small section of the ship's fuel line plumbing.

It was the latest in a series of mishaps in recent months above and beyond the hydrogen fuel leaks that have disrupted the launch schedule at the Kennedy Space Center and have raised questions about quality control and NASA's ability to keep the shuttle program on schedule.

But Forrest McCartney, director of the Kennedy Space Center, said the incident did not indicate a trend at the shuttleport.

Meanwhile, NASA got the go-ahead Friday for Saturday's launch of Discovery when environmentalists lost in their effort to halt the shuttle's takeoff with a nuclear-powered sun probe.

In Washington, U.S. District Judge Oliver Gasch rejected the request to delay the mission for at least a year while NASA sorts out its shuttle problems.

Opponents said NASA is so eager to send up Discovery that it is ignoring the danger that would result from an accident involving the radioactive plutonium.