Balky Equipment Delays Full-Scale Shuttle Rocket Test
Balky ground support equipment Thursday frustrated engineers’ efforts to carry out the first full-scale test-firing of the redesigned rocket booster for the space shuttle.
After three attempts, four hours’ work and twice coming within seconds of firing the 126-foot-long rocket motor, officials of the National Aeronautics and Space Administration and Morton Thiokol Inc. postponed the test until Saturday.
It was to have been the first test of the rocket motor, which is undergoing a $460-million modification program to fix a leaky seal that led to the Challenger explosion 19 months ago.
Although officials were still unsure what caused the final countdown to be automatically aborted 12 seconds before firing late Thursday, they said the trouble throughout the day was not related to any of the modifications made to the rocket in recent months.
The first problem was the bursting of an underground waterline that feeds a system to cool the rocket casing after firing.
After that was repaired, the countdown was within 10 seconds of ignition when the control center received indications that turbines powering the hydraulic system that swivels the rocket’s nozzle were not turning at adequate speed.
A similar problem occurred about three hours later, when the count was 12 seconds from ignition.
Officials said they were uncertain whether there was really a turbine problem or merely a faulty sensor.
No Impact on Schedule
Richard H. Truly, NASA’s associate administrator for space flight, said the delay should have no impact on the flight schedule, which calls for a shuttle to be launched next June.
After tests of scale models incorporating a new design for the seal between segments of the huge booster rocket, Thursday’s planned firing of a full-size rocket was seen as potentially a huge step toward restoring the grounded shuttle to action.
“This is the most critical test since the redesign and recovery program began,” Royce Mitchell, director of the solid rocket motor program at NASA’s Marshall Space Flight Center, told reporters. “I can say with confidence that this motor is the most analyzed, most inspected and has had the most prerequisite testing of any motor ever.”
The redesign includes the addition of another rubber O-ring in the joint seal and heaters to assure sufficient flexibility of the sealing rings.
In tests with scale models, the new design has shown no trace of leaking, although flaws were purposely introduced.
The firing postponed Thursday employed a test motor almost identical to the twin boosters that will be used to power the shuttle from its launching pad when it returns to flight status.
Expressed Disappointment
A brief delay “won’t be of significance” to the overall test schedule, Truly said Thursday afternoon, although he expressed disappointment.
NASA and Morton Thiokol will fire at least three more full-scale solid boosters before the first shuttle launching.
The next test-firing is scheduled for November, at about the same time that the flight boosters for the next shuttle mission are delivered to the Kennedy Space Center in Florida for assembly.
The test now scheduled for Saturday is critical, Morton Thiokol Vice President Carver G. Kennedy said, because “it tells us whether we have done our analysis correctly, whether our sub-scale tests have told us the truth . . . and whether full-size, short-duration tests have been accurate.”
“We have gotten to the point where, in the paratroopers, you have learned to pack the chute, but now you have to get into the airplane and jump, and that is what we are about to do.”
The shuttle Challenger exploded 72 seconds after launching from Kennedy Space Center in January, 1986, killing its seven crew members and bringing the American space program to a standstill.
