A veteran technician who helps prepare U.S. space shuttles for launch sat in a cafeteria at the Kennedy Space Center and spoke wistfully of the late 1960s and the Apollo era -- the "fat" days. "You had a lot of people on the job then," he recalled. "When you got tired . . . somebody would come along and take over.

"With the shuttle, you don't ever get relieved. You just stay on the job until it's done," said the technician, a photographer who documents shuttle preparation and launch activities.

"One day I think I worked 17 hours," he said of the period just before the Jan. 28 launch of the shuttle Challenger, which exploded and killed its crew of seven.

"That's not normal, but it's not unusual to work 10- and 12-hour days . . . It was common talk in the hangars that they were expecting and asking too much of us."

Here at the nation's spaceport, policies formulated in Washington, and pressures generated by the National Aeronautics and Space Administration's culture, meet reality.

The moment of truth for the agency arrived when President Reagan announced in 1982 that the test phase of the shuttle was over. The program's first priority, he said, "is to make the system fully operational and cost-effective in providing routine access to space." With that directive came an ambitious, accelerated launch schedule -- and the crunch began.

The effect of the policy, as portrayed in dozens of interviews, studies by outside experts and other documents and reports, was to overtax and confuse a complex system that, according to current and former top NASA officials, was already operating on the margins of tolerances.

In their effort to make the shuttle "operational," NASA and contractor officials reorganized shuttle work to make it more like an industrial assembly line, with safety, reliability and cost "coequal concerns," even though the exotic vehicles were still experimental and the problems varied, sometimes dramatically, from one flight to the next.

The shuttle processing operation was "struggling to handle the burden of work associated with each mission" mandated under the new policy, NASA's outside panel of safety experts wrote in their annual report of January 1985.

The system began to "rattle," as one former NASA employe put it, in the following ways:

*Long hours, for key workers, came with the territory. A former top shuttle official here said that middle- and high-management personnel routinely put in 80- and 90-hour weeks, sometimes for three or four weeks running.

*In the name of operational efficiency, the number of independent inspections on the work and the hardware was dramatically reduced by NASA and the shuttle processing contractor, Lockheed.

*NASA had a shortage of places to "park its orbiters" for testing, forcing technicians to play a time-consuming game of musical spaceplanes.

*Ground support operations were hampered by confused record-keeping, a lack of organized equipment maintenance, sloppy practices and other problems, resulting in two major launch delays, and was getting worse as the launch schedule accelerated.

*A number of veteran shuttle "supertechs" retired, leaving the operation short of qualified people in certain areas, such as handling dangerous fuels.

*Engineers, mostly in Houston, continued to send last-minute modifications to intricate flight hardware, throwing work schedules, carefully orchestrated in giant "flow books," out of kilter and increasing the workload.

*The spare-parts program was in such disarray that workers routinely cannibalized parts off one orbiter for another. This compounded the workload because each time a part was removed and reinstalled it had to be retested, and the chances for creating a new error rose.

"You couldn't check anything out and be sure it would stay checked out," a former NASA engineer said. "When Challenger exploded, it had a lot of Discovery's parts on it." Technological Hubris?

Despite all this, no one at NASA was willing to cry "uncle." Many believe it was this bureaucratic drive -- what Sen. Albert Gore Jr. (D-Tenn.) has called "technological hubris" -- that prevented the agency from pausing to fix major safety and design problems such as the solid-rocket booster joint that caused the accident.

The shuttle processing operation was tedious and demanding enough when flights were coming at a rate of only four a year. But, as NASA sought to accelerate the launch schedule and otherwise accommodate new commercial and military "customers," it made a series of changes that one former NASA quality-assurance official described as "a social experiment similar to forced busing."

The agency commissioned an efficiency study by the consulting firm of Booz Allen & Hamilton, which advised that to achieve commercial success, cost-cutting would need to be given virtual equality with safety concerns. "Safety, reliability and cost will be coequal concerns, but safety will remain the 'most equal,' " the report said.

That study laid the groundwork for the most visible symbol of the agency's attempt to change stripes. This was its decision to award one contract worth $6 billion over 15 years, with incentive pay for meeting the launch schedule.

The contract went to Lockheed three years ago and consolidated shuttle processing operations previously handled by a dozen contractors. Lockheed is responsible for processing the shuttle's external tanks and solid rocket boosters as well as the orbiters.

In the past, said Lockheed spokesman Stuart Shadbolt, a team would follow each orbiter through processing. Under the new procedure, he said, the system became more like a conventional assembly line. "We moved toward more of a production flow rather than taking each individual mission as unique . . . . People stay in place and work the orbiters as they come through."

To eliminate constant reassessment of procedures then considered routine, NASA officials also reduced the scope of flight readiness reviews and inspections.

The chief criticism of these moves was that they were predicated on assertions from NASA's top management that the shuttle was no longer experimental technology, with every launch treated as a laboratory experiment.

The top priority had become making the "trains" run on time.

Thus, thousands of jobs were being transferred from the shuttle development program to space flight operations. Shuttle engineers were told, in essence, that they should alter a lifelong mindset and hold their tinkering to a minimum, changing items only "to keep promises or to improve safety," NASA General Manager Philip E. Culbertson said.

NASA engineers, primarily those in Houston, kept calling for hundreds of modifications, or "mods" as they are referred to here, to be made on flight hardware. Sometimes they were major, and sometimes coming as late as two weeks before a launch when the shuttle was on the launch pad, according to sources on the outside safety panel, the Aerospace Safety Advisory Panel and NASA officials.

John Stewart of the Tennessee Valley Authority, a member of the panel, said Lockheed complained that it "could not get a straight answer" from NASA about what had to be done to a given orbiter between flights. Instead, work "would be disrupted by these unanticipated mods that would sail in over the transom," Stewart said.

The changes -- as minor as moving a velcro strip or as major as replacing an entire engine -- had to be approved by officials at Houston's Johnson Space Center, the lead shuttle center, but they could be initiated at any of 20 agency or contractor offices around the country, NASA officials said.

"It's a real pain in the rear end to be half way through OPF Orbiter Processing Facility and have them come and say we need a mod," said NASA shuttle scheduling flow director Tip Talone. "What we have complained about is "When Challenger exploded, it had a lot of Discovery's parts on it."Technological Hubris?

Despite all this, no one at NASA was willing to cry "uncle." Many believe it was this bureaucratic drive -- what Sen. Albert Gore Jr. (D-Tenn.) has called "technological hubris" -- that prevented the agency from pausing to fix major safety and design problems such as the solid-rocket booster joint that caused the accident.

The shuttle processing operation was tedious and demanding enough when flights were coming at a rate of only four a year. But, as NASA sought to accelerate the launch schedule and otherwise accommodate new commercial and military "customers," it made a series of changes that one former NASA quality-assurance official described as "a social experiment similar to forced busing."

The agency commissioned an efficiency study by the consulting firm of Booz Allen & Hamilton, which advised that to achieve commercial success, cost-cutting would need to be given virtual equality with safety concerns. "Safety, reliability and cost will be coequal concerns, but safety will remain the 'most equal,' " the report said.

That study laid the groundwork for the most visible symbol of the agency's attempt to change stripes. This was its decision to award one contract worth $6 billion over 15 years, with incentive pay for meeting the launch schedule.

The contract went to Lockheed three years ago and consolidated shuttle processing operations previously handled by a dozen contractors. Lockheed is responsible for processing the shuttle's external tanks and solid rocket boosters as well as the orbiters.

In the past, said Lockheed spokesman Stuart Shadbolt, a team would follow each orbiter through processing. Under the new procedure, he said, the system became more like a conventional assembly line. "We moved toward more of a production flow rather than taking each individual mission as unique . . . . People stay in place and work the orbiters as they come through."

To eliminate constant reassessment of procedures then considered routine, NASA officials also reduced the scope of flight readiness reviews and inspections.

The chief criticism of these moves was that they were predicated on assertions from NASA's top management that the shuttle was no longer experimental technology, with every launch treated as a laboratory experiment.

The top priority had become making the "trains" run on time.

Thus, thousands of jobs were being transferred from the shuttle development program to space flight operations. Shuttle engineers were told, in essence, that they should alter a lifelong mindset and hold their tinkering to a minimum, changing items only "to keep promises or to improve safety," NASA General Manager Philip E. Culbertson said.

NASA engineers, primarily those in Houston, kept calling for hundreds of modifications, or "mods" as they are referred to here, to be made on flight hardware. Sometimes they were major, and sometimes coming as late as two weeks before a launch when the shuttle was on the launch pad, according to sources on the outside safety panel, the Aerospace Safety Advisory Panel and NASA officials.

John Stewart of the Tennessee Valley Authority, a member of the panel, said Lockheed complained that it "could not get a straight answer" from NASA about what had to be done to a given orbiter between flights. Instead, work "would be disrupted by these unanticipated mods that would sail in over the transom," Stewart said.

The changes -- as minor as moving a velcro strip or as major as replacing an entire engine -- had to be approved by officials at Houston's Johnson Space Center, the lead shuttle center, but they could be initiated at any of 20 agency or contractor offices around the country, NASA officials said.

"It's a real pain in the rear end to be half way through OPF Orbiter Processing Facility and have them come and say we need a mod," said NASA shuttle scheduling flow director Tip Talone. "What we have complained about is when they come in . . . . late in the process, this really gets to be a nightmare."

At the same time, the engineers were working under severe time constraints as the flight rate increased, barely having time to analyze data from the previous flight, much less fix problems, before the next flight was supposed to be ready to launch, Talone and other officials said.

A 1985 Air Force study obtained by The Post found that the system for keeping track of maintenance and repairs on crucial shuttle ground equipment was "ineffective and inconsistent." It also found that an apparent shortage of engineers and technicians had left hundreds of maintenance jobs undone and that there had been numerous instances of ground hardware failure, including two that caused major launch delays.

One occurred on a flight that was to carry Sen. Jake Garn (R-Utah) as a passenger in March 1985. As workers prepared to roll the orbiter out of the shuttle processing hangar, a heavy bucket-like "cherry-picker" used to transfer workers into the craft fell and damaged the craft's cargo bay door, causing $200,000 in structural damage, breaking a worker's leg and postponing the launch for four weeks. A NASA board of inquiry found the cause to be violations of safety practices by inexperienced Lockheed workers. Key Workers 'Worn Out'

Some union leaders say that the program's changes risked safety not only by eliminating layers of independent checks in some areas but by exhausting key workers.

Andrew Younger, a machinists union official here, said that a number of "hands-on people," such as tile teams and vehicle assemblers, were "being worn out" with mandatory 10-hour workdays, seven days a week.

"Some I met with last Thanksgiving said they hadn't had a day off since the Fourth of July," he said.

About 16,000 people are employed at the spaceport, including 11,000 who work directly on the shuttle. The rest are in groundskeeping or security jobs. About 1,100 have been laid off since the accident, according to NASA.

For shuttle workers at various levels, however, the analysis of what went wrong is not simple. Many of them joined the space program as young go-getters in the 1960s, aged with it, and are captives, in varying ways, of a glorious mystique they helped to create. That mystique called on NASA people to be virtually superhuman and near-religious in devotion to the program.

Some say newer employes lack the old dedication.

Leighton Smith, a human factors specialist who worked under contract to NASA in 1983 and 1984, said the agency had in effect "ground-ruled out human error . . . . For 20 years, their analyses had focused on hardware. They just assumed they had the right people, they trained them well and they never really looked at the ways in which people might screw up."

In defense of NASA, many agency and contractor officials say the shuttle operation before the accident was gradually working out the bugs, which they said were normal for such a complex undertaking. Negative studies and reports, they say, were part of that process and were being acted upon.

The cutbacks did not affect critical flight hardware and jobs, they say, but only eliminated needless duplication of efforts and unnecessary layers of inspection of "noncritical" items. And they say they were working to reduce overtime demands.

In any case, even NASA managers did not expect to meet launch schedules. They purposely set them high, even though this damaged their credibility. "We know we won't get a job done any sooner than the most optimistic date we set," one top NASA official said. "So we set the earliest feasible date. We expect slippage. That's how we've always operated."

In the final January days before launching Challenger, shuttle ground teams had just struggled through a frustrating, record-setting number of delays and mishaps -- including a potentially catastrophic hardware problem caught only by luck -- on the flight that carried Rep. Bill Nelson (D-Fla.) into orbit. Already behind and straining, they faced a schedule calling for 15 launches this year, compared with nine in 1985.

In a world where sweaty palms were normal, experts in and out of NASA now say they were worried about the "wrong" accident. Many expected the powerful and risky main engines to fail, not the boosters. And before the Teacher in Space flight, they were already apprehensive about two of the most dangerous and controversial missions the shuttle had undertaken -- planetary probes that had to be launched within a May "window" or be delayed at least a year at a cost of $100 million or more.

The missions require the shuttle to carry highly explosive liquid fuel in its cargo bay, as well as deadly plutonium that could produce radioactive fallout over the Earth in case of an accident in orbit.

"I heaved a sigh of relief that it wasn't going up in May," said John Brizendine of the safety panel recently, about his reaction after the shuttle accident.

These days, NASA teams, as well as a presidential commission and Congress are churning out ideas for reducing pressures on shuttle handlers and restoring flight safety to top priority.

But in the atmosphere before the accident, all the pressure went the other way.

It came from elected officials, the military, commercial shuttle customers, the foreign commercial space competition, the news media and the public, but perhaps most of all from within NASA.

A member of the presidential commission likened the game they were playing to Russian roulette.

John Logsdon, a space expert at George Washington University, said, "The agency developed a kind of emperor's new-clothes mentality; there was nobody who would stand up and say 'no can do.' "