Shuttle Trip Put Off After Joint in Rocket Leaks

The federal space agency announced Friday that it has canceled the next scheduled launch of the space shuttle after discovering that flames had penetrated protective insulation on joints in the shuttle’s solid-fuel rockets during the last launch.

The cancellation means that astronaut Shannon Lucid must remain aboard the Russian space station Mir an additional six weeks. The shuttle Atlantis was to be launched July 31 to bring her home. The National Aeronautics and Space Administration now hopes to resume flights by mid-September.

The joint that leaked was the same one blamed 10 years ago for the Challenger shuttle explosion that killed seven crew members. NASA undertook a lengthy redesign of the joint at that time.

Space agency officials insisted Friday that the joint is safe but said they want to proceed cautiously and disassemble the rockets for reworking.

“We are very confident about the design of the joint,” said Tommy Holloway, NASA’s space shuttle director, at a press conference in Houston.

Holloway said that, on a launch of the shuttle Columbia in late June, heat and soot inside the solid-fuel rockets penetrated insulation that serves as the first line of defense to protect joints that hold together segments of the motor. None of the three seals that ultimately protects each joint was penetrated, he said.

Nonetheless, the surprising damage comes amid growing questions about the safety of the shuttle system as it ages and as the shuttle budget is sharply cut.

In recent months, several high-level NASA managers have quit abruptly, expressing concern that big budget cuts were jeopardizing safety. As a result, President Clinton has ordered a major safety review that will start in August.

Safety experts said that NASA’s reaction to the discovery shows it still puts a top priority on safety but that the incident also appears to undermine the agency’s assertion that the shuttle is a mature system ready to be turned over to outside contractors.

“The privatization NASA wants assumes that they aren’t going to have problems like this,” said John Pike, a space expert at the Federation of American Scientists.

Holloway dismissed that criticism, saying the current problem does not affect either the move to private contractors or the agency’s assessment that the shuttle is a mature system.

But the cancellation will delay by about a month each of a series of flights to Mir, which will be made in preparation for construction of an international space station next year.

Lucid, a physicist, had not been notified of the launch cancellation as of late Friday because she was sleeping.

NASA officials are not worried about her staying longer in space. “Shannon is in good shape and is ready to go longer,” said Frank Culbertson, NASA director of the Mir missions. U.S. officials plan to send additional supplies to Lucid aboard Russian resupply vehicles before September, Culbertson said.

Lucid, 53, will break the U.S. space endurance record of 115 days on Monday. She has been in space since March conducting experiments.

The Atlantis mission was supposed to take astronaut John Blaha up to Mir and bring Lucid down. Now, Blaha will have to wait, after undergoing extensive training in Russia in preparation for life aboard the station.

After an intensive investigation of damage to the solid-fuel rocket joint, engineers traced the problem to a cleaner and adhesive used in the joint for the first time.

“We believe it was the adhesive,” Holloway said. “It is not conclusive, but that is our judgment of what caused it.”

The new adhesive is not as strong as those previously used and allowed insulation between rocket segments to separate, sending heat and soot shooting into the joints that hold the massive stack of rocket segments together, he said.

The cleaner and adhesive were supposed to be more environmentally friendly, because they are water-based, rather than solvent-based. NASA used them at the recommendation of the Environmental Protection Agency, NASA spokesman Rob Navias said.

Holloway said NASA has a two-year supply of the original solvent-based materials and would use them on future shuttle mission indefinitely. But Holloway left unclear why, even at EPA urging, NASA agreed to tamper with a rocket joint that had been painstakingly redesigned after it caused the worst space disaster in U.S. history.

When NASA switched adhesives, Thiokol, which makes the solid-fuel rocket boosters in Utah, test-fired a segment with the new material and found no problems.

NASA officials now believe, but are not sure, that the test-firing did not replicate the tendency of the motors to flex slightly--a motion that apparently caused the insulation materials to separate momentarily at the instant of ignition.

As NASA examined the issue, a number of officials recommended going ahead with the scheduled July 31 launch, but Holloway said that he decided to accept the recommendation of others and canceled the mission.

Holloway said NASA had assembled a team of hundreds of government and private contractor engineers who had worked around the clock to determine what caused the problem.