August 1972 brought back memories of Apollo's heyday at the Kennedy Space Center (KSC). In one high bay of the Vehicle Assembly Building, Apollo 17-the last vehicle of the lunar landing program-was completing its final tests before rollout to the pad; the booster for Skylab occupied a second bay; and in a third was a new 39-meter pedestal that would serve as the launch table for manned Skylab missions. The scene pointed up Skylab's close ties with Apollo: the programs shared common facilities, operations, and hardware. Since 1970, one office had directed both programs. Despite the similarities, Skylab introduced important changes. Saturn IB launches shifted from Cape Canaveral to NASA's complex 39. The payload of the workshop required different equipment and tests; in particular, the experiment hardware added a new dimension to the checkout.
Launch preparations, including the facility modifications, required considerable debate; but once decisions were reached, the changes went smoothly and at relatively little cost. Launch operations encountered more difficulty. Checkout revealed many defects typical of new flight hardware, but officials had expected problems and the schedule allowed for delays.
High among George Mueller's goals for Apollo Applications had been the continued employment of the Saturn industrial team. Reductions in NASA funding had dashed his hopes, and by mid-1968 KSC officials faced the problem of maintaining a Saturn IB launch team during a long period of inactivity. The team numbered nearly 3000, some 90% of whom were contractor personnel; and more than half of these were employed by stage contractors. For Saturn IB rockets, Chrysler Corporation's Space Division built, tested, and launched the first stage; McDonnell Douglas the second stage; and IBM the instrument unit.
 Other contractors were responsible for design engineering and maintenance of communications, propellant systems, and structures at launch complexes 34 and 37. During seven years of Cape operations, the Saturn IB team had compiled an impressive record of 14 launches without a failure. The Apollo schedule in early 1968, however, called for the transfer of manned missions from Saturn IB to Saturn V after the Apollo 7 flight in October. Saturn Vs were launched from complex 39 on Merritt Island. When the first Apollo Applications mission was postponed to late 1970, KSC faced at least a two-year hiatus in Saturn IB operations.1
After studying the problem and considering the conflicting interests involved, Mueller approved a plan that cut manpower at the Saturn IB launch complexes by 87%, leaving a skeleton crew of 350. The two complexes would be kept in a standby condition, with the removable equipment in storage and the principal structures periodically sandblasted and repainted Even so, the number of people retained for their specific operational skills was larger than needed for maintenance, the mix of maintenance skills was not the most economical for the job, and retention of key personnel would prove difficult. The alternative-organizing a new Saturn team in 1970-was even less attractive.2
As KSC officials pondered ways to maintain a IB cadre, a parallel study examined the possibility of using another launch site. There were disadvantages to both Saturn complexes on the Cape. LC-34 was old, undersized, and showing the effects of salt-air corrosion. Originally an Army project, its design had suffered from inadequate funding. During seven years of use, the complex had undergone major modifications including changes to support manned flights. LC-37 had been designed by NASA engineers in 1961 with a better understanding of Saturn requirements; its service structure, launch umbilical tower, and blockhouse were more appropriately sized to IB operations. But it had not yet been altered for manned launches, and that change would take nearly two years.3
The Advanced Programs Office at KSC wanted to launch AAP missions from the newer LC-39 on Merritt Island; consolidation of manpower and equipment there would save money and improve operations. Complex 39 differed from the IB complexes in two major respects. First, because of the Saturn V's huge dimensions, everything on complex 39 was oversized. Second, it embodied the mobile launch concept. At the older complexes on the Cape, technicians assembled the rocket, stage by stage, on the pad. On Merritt Island this was done within the controlled environment of the Vehicle Assembly Building. Then a crawler transported the rocket and mobile launcher to a pad five kilometers away for final checkout and launch. A 136-meter tower on the mobile launcher performed the functions of the older stationary umbilical tower. Eight service arms on the launcher tower provided electrical, pneumatic, and propellant services to various stages and modules of the space vehicle;  astronauts used a ninth arm to enter the command module. A mobile service structure, which stood opposite the tower at the pad, provided access to other points on the vehicle. LC-39 had two pads, but only one mobile service structure, which was essential for manned missions.4
The biggest problem in launching the IB from LC-39 was adjusting the launch facilities to the smaller rocket. Since an Apollo stacked atop a Saturn IB was 43 meters shorter than the Apollo-Saturn V, much of the supporting equipment would not be correctly positioned. Service arms 7 through 9 connected with the Apollo spacecraft on a Saturn V; those arms would swing far above a spacecraft stacked on the Saturn IB. Relocating the service arms was no easy task; they were actually mechanical bridges, 18 meters long and weighing up to 25 tons. Five of the arms supported the vehicle until launch and could swing clear in 2-5 seconds (hence the popular name swing arm). Work platforms in the assembly building and on the mobile service structure posed similar problems. While the work platforms did not have to swing, they were also large. Those in the assembly building were 18 meters square and up to three stories high. Besides relocating the arms and platforms, the launch team would have to reposition propellant, pneumatic, and electrical lines that nearly covered the back side of the mobile launcher.5
In a February 1969 study on launching the IB from LC-39, Boeing proposed to minimize modifications by placing the Saturn IB on a 39-meter pedestal so that the second stage and instrument unit, as well as the Apollo spacecraft, would stand at the same height as the Saturn V configuration. Thus the launch team could use the launcher's upper service arms and the work platforms of the service structure and assembly building. The modifications were estimated to cost about $5 million, one-third the cost of a new launcher. The biggest design problem involved the dynamic characteristics of rocket and pedestal at liftoff. Hold-down arms on the launcher restrained the vehicle for four seconds after the engines ignited while launch control ascertained that all systems were working properly; during this time, the thrust stretched the rocket's frame upward. If the engines suddenly shut down, the vehicle would rebound with considerable force. The pedestal would have to be strong enough to absorb that force without dangerous oscillations. Boeing suggested further studies of the rocket-pedestal dynamics.6
In 1970, following NASA's decision to complete the lunar landings before Skylab, debate reopened on launching IBs from LC-39. Grady Williams, chief of design engineering, had little quarrel with the Boeing report. Since the pedestal was the chief question mark, his office had undertaken a geometric evaluation and tentative layout, sized the pedestal members, and performed a preliminary stress and weight analysis. His deputy had found some misgivings in Huntsville about vehicle-pedestal dynamics and wind loads at liftoff, but Saturn officials seemed  willing to make the change. Williams concluded that the modifications would not delay Skylab.7
Walter Kapryan, director of launch operations, pointed out several disadvantages to the change. With only one pedestal for the IB launches KSC faced a tight checkout schedule, requiring weekend work and reducing operational flexibility. If the pedestal were seriously damaged in a launch mishap, repairs could delay the last crew beyond the eight-month life of the workshop. But operations on LC-39 would save money, particularly if NASA reached a quick decision and shut down LC-34 and LC-37. Ray Clark, director of technical support, believed the tentative estimate of a $10 million saving was too conservative and that the difference might be half again as much. He noted that dual operations on LC-39 would pose a problem during hurricane season. The center had only two crawlers to move three large structures-the two launchers and the mobile service structure. Since each transfer took seven hours, the launch team would have its hands full if a hurricane approached.8
From Huntsville, Saturn manager Roy Godfrey also asked for an early decision: first, to save money on LC-34, where modifications to ground support equipment were costing nearly $4000 a day; and second, to leave sufficient time for changes on LC-39. Allowing for a six-month study of the pedestal design and a year of wind-tunnel tests and data analysis, Huntsville needed to begin its design work in mid-July. Godfrey did not insist on an unmanned launch to test the pedestal, but he expected close center coordination in reaching a decision. He argued that the benefits of the change should cover "not only the identified cost impacts and program risks but also the probability [of additional costs and risks] when detailed analysis and tests are accomplished."9
The view was much the same from Houston, where the potential savings from an LC-39 operation offset reservations about a manned launch from an untried pedestal. The change to LC-39 would help MSC's principal contractor, North American Rockwell, by avoiding a transfer of Apollo equipment from Merritt Island to the Cape and reducing the manpower required for launch operations. Much of the savings would be lost, however, if decision was delayed beyond 15 May. Houston was well along in design work for LC-34 equipment and expected to let material contracts by June. 10
In presenting its case to Debus on 23 April, the Skylab Office emphasized that LC-39 operations would save considerable sums, while demonstrating the versatility of the Merritt Island complex. Questions during the presentation ranged widely. Did the cost estimates for LC-34 include rehabilitation costs ? The answer was no. Debus inquired about the purpose of the wind-tunnel test and the possibility of disputes when nonunion workers from Chrysler joined union personnel on LC-39. At the conclusion, the director polled his staff and found general support for the proposal.11
 A meeting in Huntsville that same day disclosed more doubts. The Marshall staff considered launching a vehicle from the pedestal as a "major technical risk" that simulations and dynamic analysis could not resolve; doubts would remain until the first launch. Huntsville's support for the move to LC-39 was contingent upon several requirements: a pedestal load test to confirm its rigidity, a pull test to measure vehicle stiffness, and three months of additional checkout time to resolve unforeseen problems.12
All parties wanted the matter settled soon; a decision after 15 May would diminish savings and a delay beyond 1 June would result in "unacceptable cost and schedule risk." At a meeting of officials from the four program offices on 27 April, Program Director Bill Schneider said that a goal of 15 May was probably unrealistic since the matter required the approval of the administrator. Anyway, Schneider was more concerned about testing the pedestal. He asked, "How do we prove we can safely launch from LC-39?" Prevailing opinion at KSC was that tests and data analysis would provide sufficient confidence in the pedestal. The deputy Saturn manager at Huntsville considered the cost savings a persuasive reason for using LC-39, particularly with NASA "under every type of pressure to limit operating costs." After the need for a trial launch was debated, Schneider closed the meeting by stressing that operational advantages should weigh more heavily than cost considerations.13
Decisions in Washington came sooner than Schneider had expected. On 29 April 1970, Myers tentatively authorized a changeover, at the same time barring any irreversible action. Administrator Paine gave verbal approval on 11 May, and four days later the congressional space committees were notified of NASA's intent to use LC-39. In June Schneider asked KSC for "substantiating data to show that flight-crew safety standards will not be degraded." Morgan subsequently sent Headquarters a plan that included design reviews, dynamic and stress analyses, a wind-tunnel program, and several pull tests to measure the deflection of the vehicle and pedestal.14
Outside KSC, doubts about the pedestal lingered. In November 1970 the program offices again considered the merits of a trial launch to train the crew and prove the system, when Chrysler officials suggested a static firing as a training exercise. After a review by the program managers, Schneider concluded that KSC's plan was sound. His recommendation against a trial launch was accepted by the Management Council the following month.15
The pedestal (milkstool in local parlance) was Skylab's most distinctive feature at LC-39. Weighing 250 tons, this was a stool for the likes of Paul Bunyan. Four legs of steel pipe more than a half-meter in  diameter supported the launch table. The columns stood 15 meters apart at the base but leaned inward to less than half that width at the top. Horizontal and diagonal pipes braced the structure. Viewed from above, the launcher table with its 8.5-meter exhaust hole resembled a huge doughnut. On its deck were hold-down and support arms, fuel pipes, and electrical lines. A removable platform over the exhaust hole allowed technicians to service the eight engines of the Saturn IB's first stage.16
Design work began in July 1970. Buchanan rejected Chrysler's bid to build the pedestal under a sole-source contract, considering the design "very difficult to fabricate . . . and apt to become distorted from the initial bath [Saturn exhaust]." Chrysler's argument that its proposal would expedite matters carried no weight, since KSC had included time for competitive negotiations. In subsequent bidding, Reynolds, Smith, and Hills (architects for the mobile launcher) won the pedestal contract. KSC opted to design the pedestal's support systems in its own shops.17
The biggest problem in designing the pedestal was to minimize vertical and horizontal vibrations. The requirements eventually set forth by Huntsville allowed only the slightest sag under very heavy loads, yet the designers were limited in the weight they could use to achieve the desired stiffness. Since the Saturn V was a near-capacity load for the crawler, the pedestal could weigh little more than the stage it replaced. KSC engineers set that figure at 225 metric tons. The effects of the Saturn's exhaust had to be considered. Although flame temperatures would approach 2700 K, it was uncertain how much of this would impinge on the pedestal. Wind loads were still another factor. During operations at the pad, the service structure would deflect much of the wind and an arm connected to the top of the rocket would damp vibrations. Neither protection, however, would be available in the final hours of the countdown. Wind-tunnel tests established a maximum permissible wind speed of 32 knots for launch. Designers considered connecting the pedestal to the launcher tower for added strength until studies showed that the pedestal would actually be stiffer than the tower. 18
Construction of the pedestal produced the only major contractual dispute over Skylab's launch facilities. In the fall of 1970, the Small Business Administration asked that the contract be set aside for one of its firms. KSC refused, stating that an "experienced total organization" was required to prevent slips in the six-month schedule. Since the pedestal was Skylab's pacing item, any delays would have a serious effect on the entire program. In asking for open bidding, the center also cited "precision tolerances of alignment and elevation far exceeding the normal industry standards." Unable to change KSC's plans, the Small Business Administration sought help in Washington from its congressional committee and NASA Headquarters. The matter dragged on for more than a month, keeping plans at a standstill. Finally in late December,  Headquarters ruled in KSC's favor. But when bids were opened a month later, Holloway Corporation, a small electrical firm in nearby Titusville, submitted the low bid, $917 000. Worse yet from KSC's viewpoint, the proposal called for fabrication by another small firm in Jacksonville. Fortunately, the episode had a happy ending. In spite of problems securing the steel pipe, Holloway and its associates completed the work on time and to specifications. Afterward, the Small Business Administration wrote Congress a letter chastising NASA for its reluctance to use a small firm.19
In its early planning, KSC shared the frustrations of other Apollo Applications offices as schedules were continually revised. The dry workshop decision provided a firmer basis on which to work, and by December 1969 the center had a preliminary launch plan. A major assumption was minimum time on the pad. Whereas Apollo operations normally took 8 weeks there, the Skylab Office aimed for 24 workdays, minimizing exposure to the weather and reducing the cost of launch operations (which in the final month ran to about $100 000 a day). The center would do as much work as possible inside the assembly building, including removal of work platforms from the workshop's interior. Access to the workshop on the pad would be limited to contingencies, e.g., testing the water supply, checking a questionable instrument reading, or installing a late experiment. 20
Veterans in the Launch Operations Office doubted that the center could maintain such a tight schedule, and for the next year pad time and access were hotly debated. Charles Mars, Skylab project leader for the operations group, believed the principal investigators would demand, and ultimately gain, late access to their experiments. He wanted to plan accordingly, leaving access platforms in the workshop during rollout and allowing pad time for the scientists. At a September 1970 review of the launch schedule, Debus sided with the program office, emphasizing that "pad access would be by exception only." To Mars's surprise, the center held firm to this position for the next 30 months.21
While the workshop remained off limits, other pad requirements extended the schedule beyond the original projection. By June 1970 planned pad time had increased to six weeks, counting two weeks for contingencies. When Huntsville objected, KSC eliminated the cushion, but estimates continued to rise. At the December program review, Paul Donnelly, associate director for operations, presented a 44-day schedule, including 30 workdays. The biggest increase-9 days-involved filling and testing the oxygen and nitrogen tanks that provided the workshop's atmosphere. Donnelly agreed to review the matter further and determine what requirements could be compressed. In early 1971 the operations  office did reduce the time allowed and scheduled other tests in parallel Thereafter, planned pad time remained at 30 days. 22
The operations plan laid out for the workshop in 1971 employed a building-block approach. Components and systems of each major module would be checked out individually. Then, midway in the eight-month schedule, technicians would stack the space vehicle and begin integrated systems tests. These were particularly important because the major modules had not previously been mated, either mechanically or electrically. Before rollout the launch team would stow food, film, and other consumables. Because experience showed that the first launch in a manned program brought many unanticipated problems, the Skylab schedule ran several months longer than a typical Apollo operation. The extra months also allowed for an increase in launch activity: after August 1972, not one but three vehicles would be in work at LC-39. Apollo 17's launch in December would reduce the load, but four months later KSC faced its first dual countdown, leading to Skylab launches 24 hours apart. The magnitude of the operation warranted an early start.23
Launch of a Skylab crew required less planning, since it was essentially an Apollo operation. The extensive operations in earth orbit required new stowage plans and some new test procedures. More importantly, the change of launch sites dictated an early trial run of the LC-39 facilities. Highlights of the schedule included the only mating of the Apollo spacecraft with the docking adapter prior to liftoff, and the test of the pedestal in January 1973.24
Facility modifications were part and parcel of the operations debate, much of the discussion focusing on a new "contingency" arm for access to the workshop. The December 1969 plan called for entry through the side door, a new feature that KSC had lobbied for. In the assembly building, technicians would reach that door from service platforms; at the pad a new swing arm would provide contingency access. In 1970, the arm became the principal means of access to the workshop. The launcher's uppermost service arm (9, which Apollo astronauts used to board the command module) was relocated adjacent to the workshop's side hatch. An airlock, designed to protect the interior of the workshop from contamination, replaced the Apollo white room at the end of the arm. Rather than build a second airlock for operations in the assembly building, the engineering office recommended that the new arm be used there also.25
By the end of the year, plans for access to the rest of the space vehicle were settled. Much of the traffic to the airlock and multiple docking adapter was routed over the new swing arm. Once inside, technicians moved up the stack through the workshop's forward dome hatch. While the vehicle was in the assembly building, the telescope mount could be  reached from access ramps on the top work platform, which had been fitted with another clean room. KSC had not planned to service the telescope mount at the pad, but in mid-1970 Huntsville identified several service requirements, and arm 8 was chosen for this purpose.26
Much of the debate on Skylab operations centered on the mobile service structure, the only major item at LC-39 without a backup. The structure could be moved, but the five-kilometer trip between pads took about six hours. If operations at pad A required the service structure, pad B went unsupported for at least a day. Kennedy planners initially ruled out using the service structure for the workshop, but during the discussions on a IB launch from 39, Hans Gruene, director of launch vehicle operations, challenged that decision. Loading cryogenics into S-II stages had sometimes cracked the insulation, requiring inspection and repair on the pad, and Gruene saw no reason to believe the problem would not recur during Skylab. If the service structure were not available, an alternate means of access to the S-II would have to be devised or the rocket would have to be returned to the assembly building. The staff acknowledged the problem but did not consider it serious enough to rule out the transfer of the IB operation.27
Events that summer confirmed Gruene's prediction. In July, Huntsville stipulated that the S-II insulation would be inspected on the pad. There seemed little choice but to use the service structure for such work. While workmen could reach any part of the Saturn V from a bosun's rig, their activities were severely limited. Using the service structure for both Skylab vehicles, however, posed obvious scheduling difficulties and a few design problems as well. The payload shroud on the workshop was nearly three meters larger in diameter than the Apollo spacecraft. If workmen were to service the S-II stage from the service structure, the bottom platform would have to be extended.28
The matter bounced back and forth between KSC offices for several months before it was settled. In October, Kapryan agreed to modify the lowest platform, although the change would leave only one platform to service the lower half of the IB rocket. He recommended that the bottom platform be restored to its original configuration after launch of the first crew, so that all work stations would be available for the last two missions, pointing out that the loss of one day in the operation would cost more than the $85 000 modification. His proposal was approved.29
A few other modifications were necessary to adapt Saturn V facilities to the smaller IB. The five swing arms that serviced the lower stages of the Saturn V were replaced by a single arm, modified by adding a three-meter extension to reach the IB booster. Umbilical lines and a withdrawal mechanism were brought from LC-34. In the assembly building, a new workstand was built to reach the structural section between the two stages In the launch control center, 19 firing panels were installed for IB operations. KSC's propellants team faced a problem on the pad; the liquid  oxygen system pumped 37 850 liters per minute into the Saturn V, four times the rate the IB could accept. Rather than alter the system, the Saturn V's replenishment system was used. It pumped 4540 liters per minute, about half the desired rate.30
Initial payload testing-except for the workshop-took place in the Operations and Checkout Building, eight kilometers south of complex 39. The most notable change was the addition of a clean room for the telescope mount. Located in the building's high bay, the room rested on a support system that was designed to permit calibration of the experiment optics; specifications called for the plane of the floor to move less than five seconds of arc in a 24-hour period. Adjacent rooms housed the air conditioning unit and ground support equipment used to test the telescopes. A second modification altered the dimensions of the integrated test stand used for systems testing on the Apollo spacecraft, placing the command module at the bottom level and allowing an important mating test between the spacecraft and docking adapter. In a less noticeable change, the Apollo laboratories were modified to accommodate Skylab experiments. 31
The first pieces of the pedestal arrived at the construction site outside the assembly building in April 1971. The pipes were sandblasted, painted, and welded into six-meter sections. Baseplates were installed on the launcher floor, and by early May the pedestal was taking shape. The eight segments of the launch table came in mid-June. The table was placed atop the pedestal in early July and an access bridge from the launcher was added shortly thereafter.32
That fall contractors outfitted the pedestal and began constructing the clean rooms. The pedestal work included the installation of engine service platforms, new fuel and power lines, and a quench system to cool the exhaust. The clean room in the checkout building got off to a late start because of problems with a partition between Apollo 16 operations and the Skylab work. By Christmas, however, the work was on track. The modifications in the checkout building continued without a major problem.33
For checkout purposes, experiments were divided into three groups according to complexity. About half fell into the simplest category, which did not require continuous support from the development center or contractor. This hardware was normally installed before it reached Kennedy and was not removed for test purposes. Experiments in the second group warranted continuous support from the developer. Most of this hardware required off-module testing. The group included about 40% of the experiments, including the earth-resource instruments and most of the corollaries. The third group, preflight and postflight medical experiments, involved no functional hardware, and the development centers retained responsibility for preparations.34
 The testing of experiment hardware was complicated by the many interfaces. Skylab carried over 70 experiments, most of which connected to or operated in conjunction with other experiments and flight hardware. As one example, the ultraviolet panorama telescope, developed in France to photograph stars, had eight separate parts that interacted with each other and with seven other items of flight hardware. Altogether, the telescope depended on 41 interfaces for successful operation; of these, more than half had to be tested at the launch site. The French instrument was in group one, the less complicated experiments. The many interfaces were tracked with a fit-check matrix, a chart that listed all hardware connections and when they were verified.35
Most of the checkout was performed by module contractors; thus an experiment mounted in the workshop was tested by McDonnell Douglas. Contractors were responsible for receiving inspection, bonded storage and handling, installation and removal of experiment hardware, preparation of documents, planning and coordination of the checkout, and resolution of anomalies. When hardware was removed from the module, responsibility reverted to the development center, working under Kennedy management.36
Principal investigators were considered to be representatives of the development center. Although they were not directly involved in the prelaunch checkout, many participated in the operation. A Kennedy engineer assigned to each experiment served as the point of contact, and the scientists were encouraged to review test procedures and data. The responsible centers arranged the investigators' activities in advance, however, to minimize interference with the test schedule. The investigators were handled with care; some of them had political connections in both the legislative and executive branches and would not be shy about complaining. As a rule, investigators who did not visit the Cape were less tolerant of test restrictions. Those who saw the complexity of the operation at first hand accepted its constraints.37
The launch team had little trouble defining spacecraft test procedures with Houston, since the command and service modules differed little from their Apollo counterparts. Coordination with Huntsville was another matter. For much of the planning phase, Marshall and Kennedy were at loggerheads over workshop test procedures. The problem was twofold. Huntsville was used to dealing with Hans Gruene's launch vehicle operations team, a group that had once been a part of Marshall. Over the years, the Saturn engineers developed a close relationship. Checkout of the workshop, however, came under Ted Sasseen's spacecraft operations office, with which Huntsville had worked little. Establishing new relationships usually takes time and this proved no exception,  but adjustment was made more difficult by Marshall's overzealous concern for its Skylab hardware-or so it appeared outside Huntsville. NASA's practice was to have design centers define test requirements from which Kennedy prepared test procedures. The centers reviewed the procedures, ironed out areas of disagreement, and the launch team then conducted the test. In this case, Huntsville seemed determined to run the operation, particularly the first integrated-systems test. The two centers took more than a year to reach a compromise.38
A second dispute concerned preflight tests of the telescope mount. Its checkout represented the first time that a manned spaceflight center was to perform tests at the launch site (previously contractors had done the actual testing), and some misunderstanding was likely. The full extent of the disagreement came to light in December 1970 at a review of telescope mount flight procedures. Gene Cagle, engineering manager for the telescope mount, took immediate exception to the Kennedy position that his group would perform as a contractor. Even had Huntsville been willing to assume the subordinate role-and it was not-Cagle lacked the manpower to meet Kennedy's requirements. The preflight procedures listed 73 forms that the test team would maintain, many of which required several signatures at various levels. Cagle contended that he had barely enough people to do the actual checkout, much less fill out the paper work. He also objected to the requirement for quality assurance. He estimated that it would take 700 men, three times the number he had, to comply with Kennedy's rule that an inspector must verify each testing step. Furthermore he objected to the launch center's applying its philosophy of quality control to a Marshall operation. At Huntsville, the testing organization assured the quality of its own work.39
Kennedy officials turned a deaf ear to Cagle's criticisms. Their procedures embodied wisdom acquired over many years in the launch operations business. The atmosphere at the Cape before a major launch was quite different from the relatively relaxed conditions of checkout al Huntsville. With thousands of people pushing towards the same deadline, a formal system of paper work was essential. Short cuts inevitably brought on bigger problems. Besides, contractors managed to work within the system. Cagle's request for manpower assistance from Kennedy was denied, since it violated the center's checks-and-balance philosophy. Neither side appeared willing to give an inch, and the meeting was temporarily adjourned.40
It took nearly a year to bridge the gap. Spacecraft operations helped by lending Cagle some systems engineers from its liaison team in Huntsville; that group followed the telescope to Houston and then to the Cape working as part of Huntsville's test team. Kennedy also agreed to perform quality checks, as Houston was doing for the thermal vacuum test; Marshall in turn attempted to meet Kennedy's other requirements. The  actual checkout of the telescope mount went very smoothly; afterward Debus recognized the test team's work with a letter of commendation.41
When flight hardware arrived in mid-1972, the launch team moved to center stage, where it would remain for the next nine months. The first spacecraft (CSM 116) arrived aboard NASA's Super Guppy on 19 July and moved directly to the Operations and Checkout Building. The following week the spacecraft underwent inspection in an altitude chamber. During the next two months, the checkout would be scheduled around Apollo 17 requirements. 42
The workshop's S-IC booster (number 513, the 13th flight article in IC stage production) arrived from New Orleans aboard the barge Orion on 26 July. By 22 August all four propulsion stages for the first two vehicles were on hand. Skylab's pace quickened after the Apollo 17 rollout and the Labor Day break. During the next two weeks, the stages were mated atop their launchers. On 22 September the workshop and payload shroud completed a two-week trip from Huntington Beach, California, on the Point Barrow, a specially equipped vessel of the Navy's Military Sealift Command. The telescope mount flew in aboard Super Guppy. Within a few days, the workshop joined the Saturn V in high bay 2. 43
Early operations went smoothly, in large part because the launch team was working with proven equipment and procedures. One of the first new tasks, deployment of the meteoroid shield, ended the clear sailing. The test, scheduled for 3-7 October, was a milestone, since technicians could not enter the workshop until the deployment was verified and the shield refitted around the access door.44
Before conducting the test, McDonnell Douglas had to rig the shield in its launch configuration, snug against the workshop wall. In a job somewhat like fastening a corset around a sleeping elephant, 32 technicians wrestled the 545-kilogram shield into place around the workshop. Trunnion bolts running the length of the shield were then tightened to draw it against the outer skin. The fit was unsatisfactory. Several bulges remained, and there were two-centimeter gaps along the upper and lower edges of the shield assembly. The basic problem was that the flight shield differed in several respects from the static-test article, which had been used for earlier deployment tests. After several futile attempts to follow the prescribed procedure, the launch team began experimenting. Technicians loosened the bolts that fastened the ends of the shield's 16 panels, pushed the panels against the tank, and retightened the bolts. The gap remained. The panels were manipulated in other ways with little more success. McDonnell Douglas finally called a halt and scanned the shield....
The meteoroid shield, above. The overlapped ends were joined by trunnion bolts, used during rigging to tighten the shield against the workshop. The extra circumference required when the shield was deployed was provided by foldout panels, released by ordnance. At right, one of the 16 torsion rods and swing links that moved the shield (at top, darker) out to the deployed position. The lower end of the auxiliary tunnel, which would figure in the launch accident, is visible. MSFC 028356.
 ...with an ultrasonic device: 62% of the surface was touching the workshop. The workshop was then pressurized and the contact areas again mapped: 95% of the two surfaces were in contact. Since the pressure differential between the workshop and the shield would be substantially higher during flight, Huntsville accepted the rigging.45
Once in orbit the shield would be deployed to stand 13 centimeters off the workshop, and verification of deployment added to the launch team's troubles. On the first try, two latches that helped fasten the shield in place during flight failed to engage. Three of 16 torsion rods used to rotate the shield outward appeared overtorqued, and 1 was subsequently replaced. On the second test, the upper latch failed again. As the lower latch was sufficient to retain the shield, Huntsville accepted the condition. The final rigging for flight began in late October, several weeks behind schedule. 46
Tests of the workshop launch vehicle began in early November, in parallel with checkout of the workshop. In mid-November, the two solar arrays-their wings folded in-were mounted to the workshop. Tests on the refrigeration system were completed by Thanksgiving and on the waste-management system by Christmas. The Saturn IB was rolled out on 9 January.47
The airlock and docking adapter arrived on 6 October, the last major items to reach the launch center. During the next four months, all modules were examined exhaustively in the Operations and Checkout Building. Testing of the telescope mount uncovered few major problems, and by mid-January the Huntsville team had attached its thermal shield and solar arrays. Other hardware proved more troublesome, in particular the earth-resource experiments, which had been among the last added to the Skylab program. As late as January, Martin Marietta was reporting problems with signal conditioners, videotape recorders, and the heat control for the window of the multispectral camera.48
End-to-end tests on the earth-resource instruments proved particularly frustrating. In these exercises, technicians simulated subject matter for the cameras to record. After the equipment ran through a typical operation, video tapes were removed and the results checked against the input. Repeatedly, significant fractions of the data were not recorded. Eventually the Martin team, at the suggestion of a KSC employee, tried two rudimentary procedures-cable wiggling and pin probing-that were outlawed at the Denver plant. During a test, a technician wiggled each cable at a specific time. Comparison of the movement with data output identified half a dozen erratic channels. A subsequent probing o cable connector pins revealed several defective joints. With new con rectors, the instruments performed satisfactorily.49
The problems with the earth-resource experiments were typical 0 Skylab. During eight months of prelaunch operations, one-third of the....
...hardware required repairs in place; another one-fifth caused mechanical problems during installation. More important, 61% of the experiments had to be removed from Skylab because of test failures or late design changes, greatly increasing the checkout time. Besides the hours spent removing and reinstalling hardware, the changes entailed retesting of all interfaces. The experiment project officer at KSC concluded that the experience did not support the theory that as industry gains experience in building and testing space hardware the product will get better and there will be fewer failures at the launch site." He noted that much of Skylab's hardware was pushing the state of the art and was therefore highly susceptible to test failures and design changes. From the test results, he estimated that about one-third of Skylab's experiments would have failed in space without the launch checkout.50
 Program officials gathered at Merritt Island on 19 January 1973 for the design certification review of the launch complex. The review was the last of a series dating back to June 1972 in which the manned spaceflight management council had examined Skylab hardware, experiments, and mission operations (p. 122). The meeting at KSC focused on single-point failures,i such as the mobile service structure, and those elements of the launch complex that had undergone significant change from Apollo operations. No major shortcomings emerged from the review; at its close, KSC and Marshall were asked to complete action in a dozen areas, among them dynamic analysis of the pedestal and a review of previous IB launch problems. 51
The trip also gave Schneider a first-hand look at the lagging operation. Testing on the airlock-docking adapter had fallen four days behind in early January, raising doubts that the launch team could stack the modules on the Saturn V by the 19th. Postponement became a foregone conclusion a week before the deadline, when the launch team had to remove the control and display panel from the earth-resource experiments. The test office, faced with another week's delay, rescheduled the mating for the 29th. Upon reviewing the various test problems, Schneider concluded that the entire schedule should slip at least two weeks. The lost time might be made up, but further delays were just as likely. In announcing the decision, a NASA spokesman noted that "the current posture cannot be attributed to any one item, but is a result of the first-time testing of the modules and the many experiments." Tentative dates of 14 and 15 May were set for the first launches. Firm dates were to be established in late March.52
Fewer problems cropped up during the next two months. An integrated systems test begun on 9 February represented the first test of the workshop and its launch vehicle as a unit. The 10-day exercise went smoothly except for minor problems in the refrigeration system, most of them involving ground support equipment. On 20 February, Rockwell brought the Apollo command and service modules to the assembly building for mating with the Saturn IB. The stay was brief; within a week that vehicle was on the pad. March was a month of testing and loading. On the 7th, Martin Marietta finished the last of four simulated passes with the earth-resource cameras. Two weeks later the entire launch team ran through a simulated countdown and liftoff of the workshop during the flight readiness test, the last major milestone before the vehicle left the assembly building. The exercise continued four more days, testing the.....
....initial workshop operations. At the same time, technicians were loading provisions; by the end of the month, that job was 70% complete.53
During the final two weeks in the assembly building, the launch team conducted a series of crew compartment fit and function tests, a final inspection ensuring that everything was in its place. The test office report of 12 April concluded, "the internal OWS is closed out for flight." Final actions in the high bay included the installation of the payload shroud, a relatively simple shell that covered the telescope mount during launch The ordnance used to separate the stages or to destroy an errant vehicle was added on the 14th, and the workshop rolled out two days later.54
On the pad, first order of business was to connect and test various support systems: fuel, water, electricity, environmental control, and high-pressure gas lines. On the 25th, the launch team began the countdown demonstration test, a dress rehearsal of the final week. For 10 years this exercise had climaxed Saturn prelaunch operations; on Skylab, however, it was even more important as a test of integrated operations for two space vehicles. Months of planning paid off when the dual countdown proceeded without a major hitch. Following simulated liftoffs on 2-3 May, fuel tanks were drained and insulation was inspected. Then a second terminal count began for the Saturn IB-Apollo-a dry run with the crew aboard.55
Program officials awaited the launch of the workshop with mixed feelings. There was pride and a sense of relief that, after long years of....
....work, the laboratory, its launch vehicle, and launch complex 39 were ready. There was also apprehension: so many things could go wrong- and had, at various times in the past. On most programs the maiden flight was only the first of several launches; a failure meant delay, sometimes costly delay, but it did not spell the end. Skylab's success, however, depended largely on the outcome of its initial launch. If something went wrong, it was doubtful that Congress would provide the $250 million necessary to try a second time.
The weather provided the suspense for the final 10 days of launch operations. After a heavy rain on 4 May, workmen discovered that the payload shroud leaked, but attempts to seal it were delayed by high winds and more rain. On the 9th, the first day of the final count, lightning struck the mobile launcher, forcing a hurried retest of vehicle systems. Fortunately the thunderstorms abated during the rest of the week, and the final countdown proceeded without a major hitch. Just before liftoff, Martin Marietta technicians rectified an oversight-attaching a metal United States flag to the docking adapter.56
At 1:30 p.m. on 14 May, the workshop cleared the launch tower and mission control passed from KSC to JSC.ii
i Single-point failures were those that would terminate the operation because there was no backup for the faulty equipment.
ii The Manned Spacecraft Center, Houston, was renamed the Johnson Space Center on 17 February 1973.