A committee that has been looking over NASA's shoulder as the space shuttle booster rockets were redesigned said Tuesday it is satisfied no safety issues stand in the way of a launch late this month or early in October.
The report, however, disclosed for the first time that a crack had been found in a strut among stored booster parts and that "the implications of the occurrence of this defect" on the upcoming flight "are being evaluated."But the committee, in a report to NASA Administrator James C. Fletcher, said, "We have no basis for objection to the current launch schedule for STS-26," the next flight.
The report was submitted by H. Guyford Stever, chairman of the National Research Council's panel on the redesign of the shuttle booster rockets. A leak in the joint between the bottom two of the four segments that make up the booster was blamed for the Challenger disaster.
"During the redesign activity, two booster components were found to have structural safety factors that did not satisfy specifications," the report said. A redesigned aft skirt on the booster "has failed to meet the ultimate design load condition required in the specifications," the report said, but will not affect flight safety.
The other problem is the cracked strut that was found among stored parts.
"We understand that the struts installed in STS-26 had been inspected in accordance with procedures and proof tested and that the implications of the occurrence of this defect for STS-26 are being evaluated," Stever wrote.
Top space agency managers were meeting at the Kennedy Space Center in Florida for a flight readiness review Tuesday and Wednesday. Presumably this was an issue on the agenda.
The NRC committee's report was the seventh since it was assigned the task of monitoring the shuttle's return to flight but was not as critical as others have been.
The committee said the five design features thought to have contributed to the Challenger explosion have been fixed. But the panel said it was "disappointed to learn" of NASA's money-saving decision to evaluate the redesign with special instrumentation on only the first three flights.
"While not every test that the panel and others might have desired was conducted before the return to flight, it is clear that the current test program has been considerably more extensive and thorough than the test program that preceded the first shuttle launch," the NRC said.
"As a consequence, we conclude that NASA can have commensurately more confidence in the redesigned SRM (solid rocket motor) than it had in the original design."