6th Rocket Test May Delay Next Shuttle Flight

NASA will have to delay its scheduled February, 1988, launching of a space shuttle if it decides to complete a testing program of the shuttle’s redesigned solid fuel rocket motor, spokesmen at Morton Thiokol Inc., the booster’s builder, said Monday.

Last year, a presidential commission’s investigation into the space shuttle Challenger disaster, in which seven crew members died, found that a faulty joint on the Thiokol solid fuel booster rocket caused an explosion. A program is under way to redesign that joint at a congressionally estimated cost of $350 million.

The National Aeronautics and Space Administration originally had planned to conduct only five of six full-scale rocket firing tests before the February, 1988, launching date, but it is now reconsidering that position, Thiokol executives said.

Full Testing Urged

The National Research Council, which has been evaluating the recovery effort by NASA since the Challenger disaster, has said that the space agency should complete all six test-firings before committing the new design to flight.

Thiokol executives said they believe five test-firings will be adequate to validate the new design.

The plan to resume shuttle flights in February, 1988, is considered “very ambitious,” Allan J. McDonald, director of Thiokol’s crash effort to redesign the booster rocket, acknowledged.

“Normally, it would take years for a routine product development,” he said, but he added that the schedule would not drive Thiokol or NASA to launch the shuttle prematurely. Space experts have doubted in recent months that NASA will achieve its goal of a February, 1988, launching.

First Test in March

Under the current schedule, Thiokol would conduct the first full-scale firing of the solid fuel rocket motor, incorporating only some of the modifications, in March, 1987.

Thiokol officers said the fifth of the six tests is now scheduled for January, 1988. The shuttle would fly the next month. That test date has already slipped two months behind its original schedule because of delays in the delivery of special tools to Thiokol’s plant here. The tools have now arrived and no further delays are expected, McDonald said.

The sixth and final test of the new design would not occur until March, 1988, the month after the shuttle’s first flight.

The National Research Council believes that a sixth test is needed to provide an extra margin of safety, but Thiokol executives said the five tests, in addition to dozens of other partial tests, will provide a significant margin of safety.

McDonald said the new joint is “several orders of magnitude” more reliable than the original joint, meaning it would be from 100 to 1,000 times more reliable.

“A year ago, it was the weakest link in the system. We have added strength to that link so that it is now twice as strong as the next weakest link,” McDonald said.

It was McDonald, along with three other Thiokol engineers, who attempted to stop the launching of the Challenger a year ago this week because of their concern over the possibility of a failure of the joint seal. McDonald eventually gained national fame for his efforts.

‘Famous Failures’

“We became famous because we tried to stop the launch, but we failed. We might be the most famous failures in history,” he said Monday.

The fifth test-firing, in January, 1988, will be designed to expose the rocket motor to the coldest possible conditions at launching. The sixth test would be designed to expose the motor to the hottest possible outdoor temperature. Because the first flight will occur in February, Thiokol executives do not believe hot weather conditions will be a factor.

‘Capture Latch’

The newly designed solid fuel rocket joint incorporates more than a dozen improvements to the original joint. The most significant change is the inclusion of a so-called “capture latch,” which reduces the amount of joint movement when the rocket fires. In addition, the latch contains a third O-ring seal, which creates an additional barrier to keep the hot gases from escaping.

The capture latch reduces significantly the amount of movement in the joint, Thiokol spokesmen said. Movement during initial ignition is thought to have created gaps that unseated critical O-ring seals in the joint and created a leak of hot gases in the Challenger accident.

Thiokol’s redesign has also eliminated insulation putty, which has been harshly criticized by space experts as an unreliable method of ensuring a seal. Instead, Thiokol will use an innovative method of gluing the insulation on different motor segments together when the segments are assembled at Kennedy Space Center. An additional feature forces the joint to tighten under pressure, rather than to expand, as it did in the original design.

Repairs Called Band-Aid

Congressional critics have alleged that the new joint features represent a Band-Aid on a flawed design. Thiokol’s McDonald responded that, if the firm had started with a clean sheet of paper, the current design would still be the result.

“I think it is as good a joint as you can make,” he said.

Thiokol has also been criticized because the corporation has done well financially over the last year despite the Challenger accident.

U. Edwin Garrison, president of the Thiokol aerospace operation, said the criticism is invalid because the company’s aerospace unit’s profits have fallen, even though the parent corporation is continuing to do well. Thiokol posted quarterly profits of $32.4 million on sales of $460.3 million in the quarter ended Dec. 31, up from net income of $32 million on sales of $480.3 million in 1985.

“The public can be assured that we will have a significant financial penalty when this is over,” Garrison said.

Doesn’t Have Contract

Thiokol is undertaking the booster redesign project without an explicit contract. Rather, it is operating under a “notice to proceed” by NASA, Garrison said. Meanwhile, NASA and Thiokol are conducting intense negotiations to set a price for the work.

Garrison said the company is likely to have to conduct the development work at a profit lower than would be normal.

But some in Congress are questioning why Thiokol should earn any profit at all for redesigning its own flawed equipment. Moreover, there is some question of whether the company should absorb some of the cost of the redesign work.

Garrison refused to discuss the cost of the work. Thiokol has a work force of 2,400 assigned to the shuttle program. Based on standard aerospace industry costs, their effort could easily cost half a billion dollars. But Thiokol officers said lower wage rates in Utah would reduce costs.