COUNTDOWN TO DISASTER : Challenger’s Last Flight : 7. AT THE CAPE : ‘A Narrow Tolerance for Error’

The sprawling Kennedy Space Center--America’s gateway to the universe--rises out of the brown, flat coastal marsh it shares with ancient armadillos and the scattered remnants of near-extinct dusty seaside sparrows.

The modern complex north of Cape Canaveral is to astronauts what St. Louis was to pioneers of the Old West: a place to outfit the wagons, put in supplies and bid fellow travelers “Godspeed.”

To America’s shuttle fleet, this is home.

Before the space program boomed in the 1960s, veteran engineers recall, “there wasn’t much here but big mosquitoes.”

Now the Cape Canaveral landscape is dominated by the mammoth Vehicle Assembly Building, a 52-story-high hangar called simply the VAB. And there are glass offices, a geodesic dome press center, reviewing stands, seven-foot-thick concrete taxiways--and big mosquitoes.

Repairs to the shuttle are completed in the Orbiter Processing Facility adjacent to the assembly building before the craft is transferred next door for mounting onto the external fuel tank and the solid rocket boosters. The assembly building is so large that in the humidity of a Florida summer it has been known to rain from inside the cavernous structure.

But it was winter when the Challenger arrived back home showing few scars from its ninth successful flight into Earth orbit last November. Gary Barrett, a quality control supervisor in the orbiter processing building, inspected Challenger as work began to prepare it for what would be its final launch.

“It was in good shape,” he said. “We’ve seen it in worse shape.”

In fact, Challenger ground teams in the past had found cleanup problems ranging from discovery of the frequently damaged heat-resistant tiles to the unpleasant residue from monkey and rodent passengers carried aloft in its cargo bay. Barrett recalled nothing unusual about the work required to prepare Challenger this time.

It was scheduled for a January launch, right behind Columbia, which lumbered to launch pad 39A shortly before dawn on Dec. 2. At the time, Challenger was getting two new main engines and a right steering rocket, surrounded night and day by technicians and mechanics. Many wear clean white jump suits and white paper hats, looking like surgeons with screwdrivers and electronic test equipment.

The “turnaround” process--trimmed from 46 to about 24 days, but still short of NASA’s 14-day goal--begins with basic housekeeping chores: cleaning up the cabin and cargo bays where even small objects can damage instruments or injure the crew. Some workers are required to tether their tools to their wrists so they won’t leave them behind. And no one enters the orbiter cockpit without passing a checkpoint where all tools and instruments taken in are recorded so they can be accounted for coming out.

“We go through close to 8,000 pieces of paper before we get the orbiter out the door,” Barrett said.

The greatest volumes of paper work are generated by safety and repair inspections and by the meticulous inventory controls that document the life histories of virtually every part in the spacecraft. It is a colossal statistical exercise. For example, a single main engine--each shuttle has three--contains 30,000 parts and pieces. Each external tank has 200,000. And every part is laser-etched with a code to identify its “pedigree.”

Pedigree histories show, for example, that the external tank that exploded during Challenger’s launch was delivered to the Cape Canaveral facility March 5, 1985, and that the aft skirt on the right solid rocket booster had been through three previous launches--including the second flight of Columbia in 1981 and a Challenger launch in 1983. Parts of the rocket boosters, in fact, had been used on as many as five other launches.

No repair can be completed without paper work, not even the replacement of a single piece of tile. A worker who detects the damage files a report describing its location and nature. The report goes to an engineer who inspects the tile, decides how it should be repaired and writes a report. As many as seven other supervisors review that decision and must approve it.

When the repair order is sent back to the shuttle ground crew, a quality control inspector examines the tile to see that the damage is as it is described in the report and then oversees its replacement by a technician. The inspector completes a repair report and the document is filed.

“Some repairs take as little as 45 minutes to do, but the approval process will take up to a couple of days,” Barrett said.

Such built-in delays tend to slow the turnaround process and frustrate NASA’s efforts to develop a shuttle schedule that operates as predictably and routinely as an Earth-based airline. NASA has continued to push for increased launches, however. And private contractors such as Lockheed, which took over increasing responsibility for inspections, eliminated inspection practices determined to be unnecessary or redundant.

The changes helped cut the costs of the shuttle program, but veteran quality control supervisors said it also may have jeopardized the safety of the missions.

For example, Bob Huddleston, a quality assurance specialist with NASA for 24 years, said: “I think we tried to push the shuttle into the operational phase so fast that the quality control suffered. People were working a couple of months sometimes without a day off, 10 and 12 hours a day, and that has to take an effect. That’s where quality suffers.”

Reduced inspection practices were defended by Donald Buchanan, a veteran Lockheed employee, who said: “I don’t think you need two guys watching you install a bolt, and that was the way it was before. It’s an insult to your integrity.”

Others wonder if the routine of shuttle preparation has become too repetitive and too tedious. One worker said it is too much “like a Detroit assembly line.”

“It’s become more like a production line operation--we’re just cranking them out,” said a Morton Thiokol engineer. “But this should be different. We’re talking about pretty tricky stuff.”

NASA acknowledged similar concerns last December after it investigated the damage during assembly of a solid rocket booster at the space center. A report from that inquiry called many workers inexperienced and “unmotivated,” and it warned that boredom resulting from repetitive work was a problem.

Signs of concern over safety and quality workmanship are evident throughout the space center. In the assembly building, extensive safety precautions are observed. Every few feet are yellow or red signs warning: “Danger . . . Caution . . . You’re the hardest item to replace in the space shuttle program. Be safe.”

Workers wear fire-retardant jump suits, and all matches and cigarette lighters must be relinquished at the front door.

“If you started a fire in there, nobody’d get out,” Huddleston said.

There also are constant reminders of those whose lives depend on the quality of shuttle maintenance and repair work. When Challenger returned home, framed photographs of its next crew and schoolteacher passenger went up on walls leading to the work areas.

As the Challenger launch date approached, one of the space program’s contractors printed badges with the names of Challenger’s crew. Barrett, 33, said he planned to give his to his grandchildren some day.

Commander Scobee and astronaut Resnik visited the work areas during preparations for the flight. They pushed a few buttons, examined the work, made a few suggestions and signed autographs for the workers.

“You might lose sight of the past missions, but as far as the next ones . . . you know who you’re working for,” Barrett said.

The familiar, bulky profile of the shuttle begins to take shape in the assembly building when the external tank and newly assembled solid rocket boosters are mounted together. For the Challenger mission, sections of the boosters had been arriving by rail from Utah since the preceding August.

A Morton Thiokol engineer--who worked on the assembly, or “stacking,” process that took five days--said the procedure has “a very, very narrow tolerance for error.”

He recalled that, in a previous year, a booster rocket had to be disassembled and put back together because a single strand of hair had become lodged between two of the segments, causing a malfunction in a test. The culprit wasn’t discovered until after an exhaustive search of the huge booster rocket.

The engineer, who asked not to be identified, called assembly of the 1.1 million pounds of explosive rocket boosters “extremely demanding work. It does not forgive you for mistakes.”

Retired crane operator Edward F. Stanga remembered the pressures of handling those dreadful giants:

“We did it at night when there’s no one around. You drop one and it’s goodby, Charlie!”

The refurbished Challenger was mated to the booster rockets and external tank on Dec. 16. A 250-ton crane in the assembly building muscled the black-and-white spacecraft into its launch-ready upright position for attachment to the empty fuel tank, already fitted with detonation devices. The explosives, capable of being activated by ground-based radio signals, represent a macabre “insurance policy” for populated areas possibly vulnerable to a misguided launch.

The completed shuttle assembly moved to newly renovated, $150-million launch pad 39B on Dec. 22, a 4.25-mile trip from the Vehicle Assembly Building that took eight laborious hours.

On the low marshy Florida coast Challenger stood erect--but barely visible--surrounded by a man-made gray-and-white cocoon of scaffolding, pipes, cranes, cables and service equipment awaiting its scheduled launch date, still a month away.

It would remain under wraps until 13 hours before launch, when dozens of high-pressure sodium lamps came up to bathe the craft in an orange glow. “It lights up like a big butterfly,” an admiring, retired NASA official said.

Challenger was to be the first manned spacecraft launched from pad 39B since 1975, when Apollo astronauts flew to a rendezvous in orbit with Soviet Soyez cosmonauts.

There also were other firsts in store for this mission. The 16-day gap between launches of Challenger and Columbia--still waiting at nearby pad 39A due to a frustrating series of delays--would be the shortest in shuttle history. The Challenger’s 4.53-million-pound payload would set a shuttle weight record. And the slimmed-down booster rockets, fuel tank and orbiter made this the lightest shuttle assembly ever launched--about 45,000 pounds trimmer than the original design.

But by January, Columbia’s problems with repeated delays was threatening to push back Challenger’s launch date. Columbia had gotten within 15 seconds of main engine ignition on Dec. 19 when a faulty electronic indicator canceled the launch.

Tension tends to build around the space center at such times. Launch cancellations take a heavy toll in man-hours and cost. An overnight delay, for example, can cost between $200,000 and $300,000.

During that period, Jack Fortier, a rocket booster inspector with Morton Thiokol, was having trouble sleeping. “I had a premonition,” he said. He kept waking to an image of the Columbia exploding.

Bad weather caused more delays. But finally, the Columbia and its congressional passenger--Rep. Nelson--successfully rocketed into the pre-dawn sky on Jan. 13.

Fortier was relieved. And the way was cleared for Challenger’s launch.