For the first time since a faulty "O-ring" seal led to the space shuttle Challenger disaster in January 1986, a leak has been discovered in an O-ring of a redesigned Thiokol booster being prepared for launch.
Steve Lawson, spokesman for Thiokol, the Utah company that makes the boosters, said the leak was discovered by Thiokol personnel working at Kennedy Space Center, Fla. "Finding the leak demonstrates that the inspection process does work and that we can safely fly," he said.But the discovery came at the politically worst time possible for Thiokol, as Congress is fighting about whether to replace its boosters with a new generation booster built at a government-owned Mississippi plant. (See accompanying story.)
June Malone, spokeswoman for NASA's Marshall Space Flight Center, said the problem was discovered in routine testing at Cape Canaveral as the three solid-propellant sections of the right booster for a November launch were stacked together.
"We now do a high-pressure check of 1,000 pounds per square inch on the primary O-ring to make sure we have a good seal," she said. "A change in pressure between the primary and secondary seals showed we have a leak."She said, "The booster will be dismantled, and the O-ring will likely be replaced. Engineers will conduct a thorough inspection and analysis of the original O-ring. Potential causes for the leak could include even minute debris, contamination or improper seating of the O-ring."
Malone added, "We have had 150 successful joint leak checks in the 25 missions since Challenger. This is the first problem we have found."
She noted the redesigned boosters have three O-rings, plus another protective chamber to prevent hot gases from burning through the rocket and causing an explosion. Booster joints before the Challenger disaster in 1986 had only two O-rings for protection - and tests of them were not as stringent.
Utah members of Congress expect some of their colleagues to use the incident to argue that Thiokol boosters are unsafe and should be replaced. Malone said, "I suppose this could be blown out of proportion, but it is not that major of a problem."
NASA expects the right booster for the upcoming launch to be reassembled by the end of the week.
Thiokol Corp. makes the boosters at its northern Utah plant, 20 miles west of Brigham City. The O-rings are made by Thiokol subcontractor Hydra-Pak of West Jordan.
Lawson, Thiokol's manager of public relations, said the leak check was one of 120,000 inspections carried out "to prevent even the smallest flaw from escaping detection." Finding the leak shows that everything is done to ensure the safety of the space shuttle crews, he said.
"The redesigned solid rocket motor manufactured by Thiokol Corp. incorporates redundant O-rings and internal barriers for fail-safe flight," he said.
Engineers were planning to unstack the booster segment so they could inspect the leaking seal and determine the cause of the anomaly. Possible causes include contamination or improper seating of the O-ring.
"Cleanliness and contamination-control precautions are emphasized during the assembly procedure, and have been effective for the previous 150 field joint assemblies for the 25 flights of the redesigned solid rocket motors," Lawson said.