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

February 09, 1986

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.

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