Testing the Booster (SA-2 - SA-4)

After the launch of the first Saturn rocket on 27 October 1961, the rest of the research and development schedule went like clockwork. The nine remaining launches of the Saturn I program (April 1962-July 1965) set a record for consistent performance while receiving a minimum of recognition. The launches coincided with America’s first successes in manned spaceflight and all eyes were on the astronauts. When one of them was cradled out into space in a Mercury shot, the nation paused to participate by television in the liftoff, flight, and recovery.

While no human passengers lent drama to the Saturn I flights, Saturn team members had much to be proud of. The ten launches proved the clustered booster concept, the hydrogen-propelled upper stage, and the Cape’s ground facilities. In 1964, in what was to become a historic collaboration, the Saturn rocket and Apollo vehicle were mated for the first time, with both SA-6 and SA-7 flying an Apollo “boilerplate” model.^* The last three Saturn vehicles carried Pegasus, a satellite flown in low earth-orbit to detect meteoroids. Although Marshall Space Flight Center engineers introduced new features in every Saturn I launch, the tests came off without a major failure. The confidence gained from these successes was Saturn I’s great contribution to the Apollo program.

SA-2 (25 April 1962)

The second Saturn I, vehicle SA-2, arrived at Cape Canaveral on 27 February 1962. Launch preparations took 58 days. Although there were no serious delays, daily status reports revealed many minor problems:

Marshall engineers had made one significant change in the SA-2 booster design, placing additional baffles in the propellant tanks to prevent a recurrence of the sloshing experienced in the latter part of the SA-1 flight. The countdown on 25 April went smoothly; the only hold came when a ship strayed into the flight safety zone, 96 kilometers downrange. The successful flight was terminated with a dramatic experiment. When SA-2 reached an altitude of 105 kilometers, launch officials triggered the command destruct button. Project “High Water” released 86,000 kilograms of water from the dummy upper stages, giving scientists a view of a large disturbance in the upper regions of the atmosphere. A massive ice cloud rose 56 kilometers higher in a spectacular climax.²

SA-3 (16 November 1962)

A tropical storm greeted the SA-3 vehicle’s arrival at the Launch Operations Center on 19 September 1962. Three days of rain and high winds delayed erection of the booster, and conditions were still unfavorable when the launch team resumed work on the 21st. Aeronautical Radio Incorporated engineers, hired by NASA to review Saturn operations, reported: “The erection operation was safely performed but is rather hazardous, with technical personnel climbing around on top of the horizontal booster to install hoisting equipment. This operation was performed on the slick plastic covering of the S-1 stage in a wind of up to [37 kilometers per hour].” The Aeronautical Radio team considered the preparation prior to stage erection (removing the end ring segments) “a relatively slow, inefficient, and dangerous operation, with a considerable amount of trial and error,” and recommended more familiarity with the instruction handbooks. During the eight-week checkout, the Washington, D.C., firm found other shortcomings such as “the use of metallic hammers to urge recalcitrant components into place.” The observers noted that proper tools were not always handy, “and expediency sometimes prevailed.” They concluded, however, that the “efficiency and dedication” of Hans Gruene’s Launch Vehicle Operations Division^** was instrumental in the success of the Saturn test.³

SA-3 lifted from Cape Canaveral on 16 November 1962. Debus asked von Braun not to invite outside visitors, as the United States armed services were still on alert for the Cuban missile crisis. The rocket incorporated a number of important new features. The first two Saturns had used 281,000 kilograms of propellant, about 83% of the booster’s capacity. Marshall, wanting information for the new Saturn IB program, flew SA-3 with a full propellant load to test the effects of a lower acceleration and a longer firststage flight. The flight also tested the retrorockets that would separate the two live stages on SA-5, the first launch of the upcoming block II series. SA-3 flew three other important prototypes: the ST-124 stabilized platform, a pulse code modulated data link, and an ultrahigh-frequency link. The stabilized platform was a vital part of the Saturn guidance and control system, containing gyroscopes and accelerometers that fed error information to the control computers, which provided steering signals to the gimballed engines. The data link’s importance lay in its ability to transmit digital data, a vital ingredient in plans for automation of checkout and launch procedures. The ultrahigh-frequency link would be used to transmit measurements, such as vibration data, that could not be handled effectively on lower frequencies.⁴

SA-4 (28 March 1963)

SA-4 set records for the shortest launch checkout (54 days) and the longest countdown holds (120 minutes) of the block I series. At T-100 minutes on launch day, test conductor Robert Moser called a 20-minute hold while the launch team adjusted the yaw alignment of the ST-90 gyro guidance platform. Readings from a ground theodolite showed that the platform was not properly aligned on the launch azimuth. An operator oriented the Watts theodolite on a geodetic survey line and then turned the head of the instrument to the launch vehicle. The alignment prism in the ST-90 platform reflected a light directed from the theodolite. If the platform was aligned properly, the reflection from the prism appeared in the center of the theodolite’s scope. In this case, the problem was with the theodolite and not the gyro platform.

The final hold came at T-19 minutes as a result of a LOX bubbling test. Andrew Pickett’s propulsion group performed the test late in the countdown to verify the flow of helium to the LOX suction ducts of the eight engines. The decreasing temperature of the LOX indicated a proper flow of helium, but the propulsion panel did not register a signal that the LOX bubbling valve was open. Without the signal the terminal sequencer would shut down. Pickett’s team, along with Isom Rigell’s electrical engineers, improvised a bypass for the valve signal on the sequencer. The propulsion team assured a proper LOX temperature for the Saturn and then initiated the bypass manually as the sequencer brought the vehicle to liftoff.⁵

In SA-4’s most important test, officials deliberately shut down the number 5 engine 100 seconds after liftoff. Booster systems rerouted propellants to the seven other engines. Contrary to some predictions, the shutdown engine remained intact and the imbalance of hot gases on the engine compartment heat shield had no ill effect. The SA-4 vehicle simulated all block II protuberances on the dummy second stage, e.g., fairings and vent ducts, to determine the aerodynamic effects of a live second stage. Block II antenna designs were also flown. The SA-4 vehicle employed a new radar altimeter and two experimental accelerometers for pitch and yaw measurements. After the successful flight, the von Braun team in Huntsville looked confidently toward two-stage missions.⁶

Pad damage from the first four launches did not surpass expectations. Restoration cost an average $200,000 and took one month. LVOD officials were particularly interested in assaying pad damage after the launch of SA-3. One of the mission’s goals was to determine the effect on the pad of an increased propellant load with the consequent slow acceleration and longer exposure to rocket exhaust. The damage was comparable to the first two launches. The only effect readily attributable to the slower acceleration was increased damage to the pedestal water deluge system (the torus ring) and a warping of the flame deflector.⁷

The LOX fill mast at the base of the rocket had to be replaced after each launch. The 21-meter cable mast assembly extending up alongside the rocket also crumpled during each of the first two launches. After watching the long aluminum fixture collapse the second time, officials replaced it with an umbilical swing arm. The Huntsville engineers converted a swing arm intended for the SA-5 launch and shipped it to the Cape in early August. At LC-34, Consolidated Steel and Ets-Hokin-Galvin began work on the new umbilical tower two weeks after the SA-2 shot.^*** The swing arm, mounted in August, suffered very little damage in the SA-3 launch.⁸

A Second Saturn Launch Complex-LC-37

Block I - the first four Saturn launches had gone up from launch complex 34. With the block II launches (SA-5 through SA-10), the program would move to new facilities at launch complex 37. The second complex had originated with the Hall Committee study of 1959, which found that an explosion would render LC-34 useless for a year [chapter 2]. On 29 January 1960 Debus asked Dr. Eberhard Rees to approve a second Saturn complex. Since LC-37 would serve primarily as insurance for LC-34, no major design changes were anticipated. Taking into account the rising costs on complex 34, Debus estimated the price of LC-37 at $20 million (roughly one-third more than LC-34’s costs as of January 1960). In his report, Debus warned Rees that LC-37 would likely be sited at the undeveloped north end of Cape Canaveral, 1,220 meters north of LC-34 and 425 meters from the Atlantic Ocean. A complex at that location “would require utility capacities of unusually large magnitudes and the cost to Saturn, as the initial [user] could be excessive.”⁹ In February 1960, representatives from the Missile Firing Laboratory, Army Ballistic Missile Agency, and the Air Force Missile Test Center estimated demands for water, power, roads, communications, and instrumentation at LC-37 and discussed the cost of extending these to the proposed site. Eventually, development for LC-37 included a new electrical power substation and transmission lines, a 3,785,000-liter water reservoir, and a pumping network, at a price of $2.5 million.¹⁰

Hoping to have LC-37 ready for backup duty by January 1962, MFL originally set a mid-1960 deadline for criteria on the launcher, umbilical tower, and propellant systems.¹¹ Debus’s decision to put a new service structure on LC-37 dashed these plans. Harvey Pierce, a Connell engineer, had prompted the change. Pierce had played an important role in designing LC-34 and more recently on the Hall Committee. On 26 February Pierce had written Debus about some inherent shortcomings in the inverted U service structure and recommended the formation of a study group.¹²

By mid-April 1960 Albert Zeiler was directing a two-pronged investigation into problems encountered with LC-34’s service structure and concepts for a larger one. The latter reflected NASA’s decision to build LC-37 for both C-1 and C-2 versions of the Saturn.¹³ The service structure committee met periodically over three months to review 21 concepts proposed by NASA officials and private industry. No proposal proved fully satisfactory; attractive features from several were combined in the final recommendation. The committee concentrated on a half-dozen aspects of the service structure design, posing these alternatives:

• Mobile or fixed structure?
• Bridge crane or stiff-leg derrick for hoisting?
• Protection for the launch vehicle from wind loading or absorption of the rocket’s wind loads into the service structure?
• Open or closed service platforms?
• Launch stand above or below ground?
• Collapsible or fixed umbilical tower?

The fixed service-structure designs were attractive since they offered economy and good utilization. The committee, however, feared the effects of a pad explosion on a fixed structure. The fixed design also posed a difficult engineering problem. Long cantilevered platforms with elaborate retracting mechanisms were needed to keep the main structural frame outside the rocket’s drift cone (the safety allowance for effect of surface wind at launch). At an 11 July meeting in von Braun’s office, Marshall officials discussed the effects of wind drift, thrust malalignment, and loss of one engine on the clearance requirement for a service structure or umbilical tower. The participants agreed to a 12-meter clearance between the vehicle’s center line and the nearest obstruction at the 91-meter level. About the same time the Zeiler committee opted for a mobile service structure.¹⁴

The hoisting matter was settled in favor of a stiff-leg derrick mounted on top of the service structure. Although a bridge crane offered more flexibility, its use in the upper reaches of the service structure would obstruct the vertical escape trajectory of a manned payload. In the final design a 40-ton mobile crane positioned at a lower level assisted the 60-ton main hook on the stiff-leg derrick.

The question of wind loads arose because the Saturn was not self-supporting in high winds. One alternative was to design “hard point” connections between the vehicle and service structure platforms. This would require additional structural members on the rocket, increasing its empty weight. It would also add considerable stress to the service platform. The committee chose a design enclosing the launch vehicle in a 76-meter silo of five sections that eliminated wind loads and protected the rocket from flying debris. The silo design also solved the service platform problem. The committee recommended a minimum of ten adjustable work platforms in the structural steel frame silo. Air conditioning would provide the necessary ventilation during propellant loading.

The committee rejected a plan to put the launch stand below ground with the flame diverted into side trenches. Doing so would reduce the height of the service structure, but the higher costs of subsurface facilities, due to Cape Canaveral’s high water table, were unacceptable.¹⁵

In designing the umbilical tower, the major concern was separation of the umbilical connections from the launch vehicle at liftoff. The committee studied jointed, collapsing towers; towers supported by cable catenaries (a curved cable suspended from two poles); and pivotal reclining structures. The size and weight of the Saturn umbilical connections - propellant piping, pneumatic lines, instrumentation circuitry, and electrical power lines - rendered all those concepts impractical. The committee recommended a free-standing umbilical tower, with ties to the service structure for support against high winds. Swing arms, entering the silo enclosure through cutouts in the platform mating edge, would connect the umbilicals to the launch vehicle.¹⁶

In August 1960 the launch team approached von Braun about adding a second pad to the LC-37 complex. The additional pad would provide a backup for Saturn C-2 launches and reduce launch time by one-third, since it would eliminate the month needed for pad repairs. Von Braun directed Debus to add a second pad on LC-37 if funds could be secured. Before the meeting adjourned, General Ostrander, Office of Launch Vehicle Program Director, arrived. After reviewing the proposal, Ostrander agreed to provide $700,000 for the initial modification work.¹⁷

Further revision of LC-37 plans occurred in early 1961. In January Debus heard of an Air Force-sponsored study on blast potentials of the Atlas-Centaur rocket. The Arthur D. Little Company findings, Debus informed von Braun, “indicated a problem of considerable magnitude with Saturn complex siting.”¹⁸ Since there was little data on liquid hydrogen’s explosive characteristics, the calculations were tentative. The Little report, however, reinforced the Hall Committee’s conclusions. On 12 January Debus asked Petrone, as Saturn project coordinator, to investigate the explosive potential of liquid hydrogen and determine the cost of extending pad distances beyond 183 meters. The distance between pads was subsequently increased to 365 meters.¹⁹

Two Florida firms won the LC-37 design contract: Connell and Associates prepared the service structure and umbilical tower designs, while Reynolds, Smith, and Hills handled the subsurface facilities. The architects’ design work extended from February to July 1961. During the same period, Gahagan Company dredged thousands of cubic meters of sand from the Banana River onto the LC-37 site. Vibroflot machines began their work at the complex in mid-July. Blount Brothers Construction Company of Montgomery, Alabama, won the pad B construction bid in August 1961 and started work the following month. The project was 45% complete on 30 March 1962, when the Corps of Engineers awarded Blount Brothers a contract to build pad A.²⁰

The new construction soon overshadowed the older Saturn facility. LC-37 was nearly three times larger than LC-34. The two umbilical towers rose 82 meters from a 10-meter-square base. Stability of the towers in high wind presented a challenge to the designers. The large number of electrical, propellant, and pneumatic lines running up through the lofty structures gave the tower surface a wind resistance nearly equivalent to a solid wall. At the base of each tower stood a four-story building (one floor was underground) containing a generator room, high-pressure-gas distribution equipment, and a cable distribution center. The building would later house digital computers for the automated checkout.²¹ Hydrogen burn ponds were an added feature on LC-37. The gaseous hydrogen boiled off from the LH₂ storage tank and the S-IV stage and flowed several hundred meters through pipes to the burn pond. The LC-37 launch control center, or blockhouse, was similar to LC-34’s, but half again as large. By far the most imposing of LC-37’s facilities was a 4,700-ton, 92-meter-high service structure, containing four elevators, nine fixed platforms, and ten adjustable platforms that allowed access to all sides of the vehicle. The six semicircular enclosures could withstand 200-kilometer-per-hour winds. When completed in 1963, the self-propelled, rail-mounted structure was the largest wheeled vehicle in the world.²²

Erection of a special assembly building was a third construction project for Saturn I in 1962. Some novel building designs were rejected before deciding on a conventional hangar configuration. The new hangar AF was in the Cape industrial area, a short distance from the Saturn dock. A bridge crane in the hangar’s main bay provided a lift capability for the initial upper stage checkout; lean-tos on both sides provided extra office space. The Launch Vehicle Operations Division performed some preliminary checkout work in hangar AF, but half of its big bay was soon given over to Gemini and Apollo spacecraft operations.²³

The Troubled Launching of SA-5, January 1964

The block II version of Saturn I (SA-5 through SA-10) represented a sizable increase in launch requirements over block I. Additional RF links, calibrations, and systems tests in the two-stage rocket nearly doubled launch checkout time. [see table 1, chapter 2]

The greatest change in the block II rocket was the addition of a hydrogen-fueled second stage. Douglas Aircraft Corporation had won the contract for the S-IV stage in April 1960, five months after NASA adopted the Silverstein Committee’s recommendation to use liquid hydrogen in the Saturn’s upper stages. The 13-meter stage had six Pratt & Whitney RL-10 engines, the same power plant that NASA intended to use in the Centaur rocket. Confidence in the S-IV stage originally stemmed from expectations that Centaur tests would prove the effectiveness of the engine long before SA-5. As things worked out, the first successful Centaur launch came in November 1963, more than two years behind schedule and only two months ahead of the SA-5 launch.

SA-5 differed in other ways from its Saturn predecessors. Engineers had increased the 340,500-kilogram capacity of the S-1 first stage by more than 31%. Each H-1 engine had been uprated to its intended 836,600 newtons, giving that stage its full thrust. Marshall had also attached eight fins to the base of the S-1 stage, four stubby fins and four longer ones that extended 2.7 meters from the rocket. These provided additional aerodynamic stability (a decision prompted by possible use in the Dyna Soar program). The guidance and control instruments for both stages flew in an experimental instrumentation unit above the S-IV stage. The payload for SA-5 was a Jupiter nosecone.²⁴

The postlaunch celebration for SA-4 was barely over when Hans Gruene’s Launch Vehicle Operations team turned its attention to the block II series. The first order of business was fitting LC-37B with a dummy SA-5 vehicle. The dummy stages were erected and mechanical support equipment tests completed by the end of April 1963. In the first two propellant flow tests, the transfer system kept the hydrogen below 20 kelvins (-253 degrees C). Chemical analysis revealed contaminants, but the liquid hydrogen cleared up on the third test, saving the launch team a detailed investigation. There were a number of routine problems such as leaking LOX lines, freezing LOX vent valves, and inoperative gauges. Only one major change was required, a modification of the baffles in the S-1 stage LOX tank. There was time for this since the SA-5 launch date had been moved from August to December.²⁵ After the wet tests were completed in late June, NASA flew the S-IV dummy stage back to California aboard a modified B-377 aircraft.^*

Gruene’s launch team erected the Saturn booster on 23 August and during the next 30 days performed mechanical system tests, calibrations for the instruments, and telemetry and RF tests. The only serious difficulty was one that apartment dwellers can appreciate - four service structure elevators that were frequently out of order and usually crowded. In the upper levels of the 90-meter-high, open structure, elevator cables were exposed to rain and wind. Maintenance problems were inevitable. In September 1963 the combined load of facilities contractors (outfitting the service structure) and SA-5 launch technicians strained the elevators’ capacity. Gruene informed Debus on the 12th that “elevator usage is now critical and may become intolerable when checkout activities require more personnel.”²⁶ Gruene hoped to finish outfitting the service structure after the normal workday to alleviate the problem.

In Sacramento, Douglas engineers completed four weeks of poststatic checkout of the S-IV on 10 September. The second stage was removed from its test stand, loaded aboard the B-377, and flown to Cape Canaveral. Douglas personnel gave the stage a thorough inspection, including the use of a sound probe to detect debonding of tank insulation. The probe was moved back and forth over the outer surface of the stage, its signal reflecting back from the inner side of the tank skin into the probe’s sensing device. An oscilloscope showed both the output signal and the echo. Welds or any other irregularities stood out clearly. Heavy winds and rain that struck the Cape the following week did not halt S-IV activities in hangar AF. However, out on pad 37B the telephones failed, the service structure elevators were temporarily shut down, and the launch team lost three days of work.²⁷

Operations reached a hectic pace in mid-October. After the S-IV stage was erected on the 11th, Robert Moser’s office revised the launch schedule to give Douglas a week longer for S-IV checkout and modifications and a combined LOX-LH₂ tanking test. Moser maintained the 6 December launch date by compressing the time allowed for launch vehicle tests in November. Even with the extra week, Douglas found the test requirements more than it could handle in a 16-hour day. On 17 October the California firm asked for around-the-clock operations until the propulsion tests were completed. Gruene, hard pressed to support the S-IV stage operations, reluctantly agreed.²⁸

The Cracked Sleeves

Although the S-IV erection was the major activity on 11 October, that day’s status report also mentioned the discovery of a cracked sleeve on the “S-1 engine position #3 hydraulic package, yaw actuator, low pressure return line.”²⁹ The sleeve, a centimeter-long metal cylinder, was an integral part of end-fitting assemblies on hundreds of pneumatic and hydraulic line joints in the first stage. Technicians replaced the sleeve on the 15th and continued the check of the hydraulic actuator. The incident, however, caused concern in Huntsville where Chrysler personnel had reported similar sleeve failures after pressurization tests. A special investigation of S-1 engines on the 22nd found 12 more cracked sleeves. These sleeves and the affected tubing were replaced during the next two weeks. The cracked sleeves apparently had little to do with the decision in late October to delay the launch another five days. Gruene blamed the delay on contamination in the S-IV engine and time lost for a hurricane alert.³⁰

The assassination of President Kennedy slowed operations for three days, but the revised schedule was still being maintained in late November. A cryogenic tanking test on the 26th started well enough. There were only minor problems as the team went through the various phases of S-1 LOX loading: the 15% slow fill, the fast fill, topping off, and replenishment. It was evening when liquid hydrogen began to flow to the S-IV stage. Albert Zeiler, arriving at LC-37 to watch the last portion of the test, heard an explosion but could not immediately contact Andrew Pickett, the Chief of the Mechanical and Propulsion Division. Inside the blockhouse, a technician at the periscope saw fire on the pad. Television monitors picked up the flames, but gave only a vague idea of the fire’s extent and location. Pickett terminated the hydrogen loading. A visit to the pad revealed the cause of the explosion. Gaseous hydrogen had leaked from a ruptured bellows in the hydrogen vent line that ran from the rocket to the burn pond. The rupture was probably caused by water seeping back into the pipe from the burn pond and then freezing when the cryogenic hydrogen entered the line. The escaping hydrogen had collected beneath the metal plates covering the vent line trench. Purging the vent line with helium quickly extinguished the fire. The launch team then detanked the propellants, leaving damage assessment for the following day.³¹ The fire caused Robert Moser to reschedule the cryogenics test for 6 December, put operations on a seven-day week, and predict a one-week delay for the launch.

Although there were problems on the next cryogenic test, launch was still expected before Christmas. On the 10th, however, the launch team detected its fourth cracked sleeve in two days. The discovery of seven more cracked sleeves the following day caused Marshall to postpone the launch for a month despite a successful simulated flight test on the 13th. In the interim the launch team replaced all of the sleeves^* in critical pneumatic and hydraulic circuits.³²

The cracked sleeves were not the last of SA-5’s problems. During the simulated flight test, D. C. McMath’s RF and telemetry section had experienced radio interference in the 400- to 450-megacycle band. Results of an RF check on 23 December provided no holiday cheer as three of SA-5’s four command destruct receivers responded to an Air Force Range signal, 42 megacycles above that used for the Saturn destruct command. Although McMath was anxious to unscramble the signal-mixing, further testing had to wait two weeks for complete external RF silence. January tests appeared to place the source of signal mixing within the service structure, but when the structure was removed on the 14th, the interference continued. Suspicion next turned to the umbilical tower, and the possibility “that RF signals transmitted from the vehicle are being mixed [there] to produce the interference.” The launch was nine days away when the RF section finally ran a satisfactory test on the 18th. Even so, the source of trouble was not definitely identified. Since some team members still considered the UDOP tracking station a possible source of interference, McMath recommended removal of the UDOP power amplifier.³³

All’s Well That Ends Well

The last weekend in January, America’s television networks prepared live coverage of the SA-5 shot scheduled for Monday the 27th. An incident on Friday had threatened to postpone the launch: during a static firing test at Sacramento an S-IV stage had exploded, damaging the test stand and support equipment. After evaluating the accident, NASA officials decided the likelihood of an S-IV engine failure was sufficiently low to proceed with the SA-5 launch.³⁴

Col. Lee James, Marshall’s Saturn I-IB project manager, and Ted Smith, Douglas director of S-IV stage development, were among the 200 who gathered at the LC-37 blockhouse on Sunday evening for the start of the SA-5 countdown. Robert Moser was test supervisor for the operation; KSC’s John Twigg and Douglas’s John Churchwell served as test conductors for the S-I and S-IV stages. There were three holds during the night: 3 minutes for network checks, a 17-minute hold for battery verification, and a 27-minute hold to change an accelerometer. Shortly after sunrise the launch team discovered a leak in the S-IV main LOX line that took 48 minutes to correct.³⁵

The countdown proceeded satisfactorily despite these minor problems. S-1 LOX loading began about 8:30 a.m. and went smoothly through the fast fill. When LOX reached the 93% level in the first stage tanks, the propellants team switched to the LOX replenish system (used to ensure a controlled slow flow). Instead of continuing its rise, the S-1 stage “mass readout” (the percentage of LOX in the tanks) began to fall. Launch officials quickly realized that the replenish system was not supplying LOX to the S-1 stage. Leroy Sherrer, Oxidizer Section chief, first thought a frozen valve might be the cause of the failure. Finding the replenish facility in order, Sherrer’s group moved up the LOX line toward the pad. W. C. Rainwater’s Ground Support Equipment Section started from the other end of the line, the base of the rocket. In less than an hour, the teams found the blockage - a “blind", flange (plate without an opening) left in the replenish line from a previous pressurization test. Safety precautions and venting problems precluded the immediate removal of the aluminum plate, and Debus reluctantly scrubbed the mission.³⁶

A tired Rocco Petrone informed 150 newsmen of the launch postponement. He admitted that failure to remove the flange was a human error, but refused to single out anyone. “It was a routine procedure that we’ve done many times before. This time we didn’t do it. We make mistakes."³⁷ Debus had an even less pleasant task - explaining the mishap to five members of the House Subcommittee on Manned Space Flight, down from Washington for an inspection. The KSC director assured the visiting Congressmen that in future operations the launch team would tag flanges with red flags, as they presently did with all electrical work. In this way any deviation from the operational flight configuration would be flagged and a record kept by test supervisors. Debus rescheduled the launch for Wednesday morning, the 29th.³⁸

There was one unplanned interruption in the second countdown, a 73-minute hold due to RF interference on the C-band radar and command destruct frequencies. At 11:25 a.m. SA-5 lifted off into a 37-kilometer-per-hour wind and a heavy sprinkling of clouds. Painted designs on the rocket’s skin aided nine unmanned and four manned cameras to track pitch, yaw, and roll movements for the first 1,000 meters. Six camera-equipped tracking telescopes, located along the Florida coast and on adjacent Grand Bahama Island, provided higher-altitude photographic coverage. Radars fed information to three computer-operated flight position plotting boards located in blockhouse 37. Another KSC computer, linked for the first time to an Eastern Test Range vehicle impact prediction computer, transmitted real time (very nearly instantaneous) vehicle position data to Marshall, as well as to Goddard Space Flight Center, NASA’s communications center in Maryland. Telemetry aboard the SA-5 transmitted 1,183 separate measurements back to seven receiving stations in the Cape area; the ground stations relayed this information by radio and hardwire^* to data processing machines in hangar D.³⁹

The launch vehicle carried eight movie cameras and a television system to record stage separation and ignition of the S-IV engines. The separation of the two stages began at T+147.2 seconds, 6 seconds after the first stage inboard engine had shut down and 0.2 second after the outboard engines had cut off. The first action was the firing of small S-IV ullage rockets which forced propellants toward the engines. As booster retrorockets fired to slow the S-1 stage, explosive bolts disconnected the two stages. The S-1 and eight camera capsules fell into the Atlantic 800 kilometers downrange from Cape Canaveral. The S-IV engines then burned for 8 minutes, placing 16,965 kilograms in orbit, the heaviest payload in history.⁴⁰

A nationwide audience viewed the SA-5 launch on television and received a remarkably clear booster engine shutdown at 60,000 meters altitude. Immediately following the launch, President Johnson telephoned his congratulations to the launch team in blockhouse 37. He told Wernher von Braun that he hoped his recent gift of a Texas hat would still fit the MSFC director. Von Braun contrasted the day’s success with the Explorer I launch six years earlier and praised the Douglas Company for its role in developing the S-IV stage. Although the achievement of earth orbit was not even a secondary goal, Robert Seamans said the mission left “no question” that the United States had surpassed the Soviet Union in “ability to take large payloads into orbit.” George Mueller, NASA’s Associate Director for Manned Space Flight, described the launch as “the first step to the moon."⁴¹

The Remaining Block II Launches, SA-6 - SA-10

SA-6 (28 May 1964)

Later Saturn I missions brought new requirements and major launch problems, but none of the subsequent operations dragged on like SA-5. Launch preparations for the remaining five Saturns averaged 91 days, 70 days less than the SA-5 operation. An Apollo boilerplate, duplicating the weight and external configuration of the fully equipped spacecraft, flew on the May 1964 launch of SA-6. Boilerplate 13, the payload for SA-6, was one of 30 spacecraft built by North American for preliminary Apollo tests. The Manned Spacecraft Center had already launched several boilerplates at White Sands Proving Grounds to test the spacecraft for land and water impact, parachute recovery, pad aborts, and water egress and flotation. SA-6 demonstrated the spacecraft’s structural compatibility with a Saturn launch vehicle.⁴²

The checkout of boilerplate 13 had begun in December 1963 when G. Merritt Preston, Director of Houston’s Florida Operations, sent George T. Sasseen to North American’s Downey, California, plant with a 40-man team. Sasseen’s counterpart on the North American staff was project engineer Robert Gore. For two months the NASA-North American team subjected boilerplate 13 to a series of rigorous tests, from assembly line inspections to simulated flights. After the spacecraft was transferred to Florida, there were more tests in hangar AF. By early April the spacecraft team was ready to stack the boilerplate atop the Saturn I vehicle. During the next six weeks, the team resolved problems in the spacecraft cooling systems and in the mechanism for jettisoning the launch escape tower. Much time was spent checking telemetry and the 116 instrumented measurements that recorded structural and thermal responses.⁴³

The 20 May launch date was postponed after liquid oxygen damaged a wire mesh screen during a test, causing fuel contamination. Six days later, a countdown proceeded satisfactorily until T-115 minutes, when a compressor in the environmental control system failed. The air conditioning gone, the temperature in the rocket’s guidance system soon exceeded tolerance and the launch was scrubbed.⁴⁴

On 28 May it seemed that Launch Vehicle Operations might postpone the third attempt. Liquid oxygen vapors, vented from the S-IV stage, obscured the line of sight from a ground theodolite to an optical window in the SA-6’s instrument unit. Winds blew the vapor away after a 38-minute hold, but adjusting a LOX replenish valve forced another hour’s delay. Then in the last minutes of countdown, the sighting problem recurred. This time LOX vapors from an umbilical tower “skid vent” blanketed the optical window. Since stabilized platform alignment control was essential to the launch, the automatic sequencer included this function among its checks. If the theodolite did not have a clear sighting, the sequencer would shut down at T-3 seconds. Quick action by two launch team members saved the day. With the count stopped at T-41 seconds, Terry Greenfield, Electrical Systems Branch chief, removed the stabilized platform reference from the sequencer’s functions by “jumpering out” several electrical wires. Meanwhile, Milton Chambers, Gyro and Stabilizer Systems chief, improvised a way to maintain the platform in its proper flight azimuth through manual control. The count resumed 75 minutes later. Ironically, the vapors blew away from the optical window during the final 40 seconds of countdown.⁴⁵

SA-7 (18 September 1964)

Since 1954 Redstone, Jupiter, Pershing, and Saturn rockets had employed a 33-pound multichanneled tape recorder, commonly called a “black box,” for inflight commands such as inboard engine cutoff, ullage rocket ignition, and fuel pressure valve openings. It was replaced on SA-7 by a computer that could be corrected during flight. SA-7 also marked the close of Saturn I research and development tests. Following the seventh successful launch, NASA officials declared the Saturn I launch vehicle “operational."⁴⁶

SA-7 set two precedents in Kennedy Space Center launch operations. In early July technicians found a cracked LOX dome on engine 6 of the S-1 stage. It was the first time the launch team had to replace a Saturn engine. The experience was not novel for long. NASA officials, attributing the cracks to the same “stress corrosion” that had plagued SA-5 sleeves, returned all eight engines to the Rocketdyne plant in Neosho, Missouri. The removal of each 725-kilogram engine took KSC and Chrysler mechanics about ten hours. As the supervisor described it: “We had to disconnect all electrical cables, unhook the hydraulic systems from the outboard engines, and disconnect LOX and fuel suction lines, the turbine exhaust, purge lines, networks and measuring cabling. It was quite a job."⁴⁷

Replacing the engines in the S-1 stage set the launch back from late August to mid-September. Hurricanes Cleo and Dora cost another half week’s work. Although Cleo struck the Cape on 28 August with 110-kilometer-per-hour winds, SA-7 was unharmed inside the service structure.^* A surprise visit by President Johnson on 15 September coincided with the first countdown demonstration test, an exercise added to the launch checkout after the blind flange incident on SA-5. Robert Moser’s Technical Planning and Scheduling Office had decided to run, as the last test, a full countdown of the fully fueled Saturn (with a mission abort just prior to scheduled umbilical ejection). The test would become a focal point of launch operations in later Saturn missions. Its first performance went smoothly, as did the launch on the 18th.⁴⁸

SA-8, 9, 10 (16 February through 10 July 1965)

Each of the last three Saturn I’s carried a Pegasus satellite enclosed within a boilerplate service module. The satellite’s function was to determine the incidence and severity of meteoroids in the region where Apollo astronauts would orbit the earth. As Pegasus was not an integral part of the Apollo program, its use raised an administrative question - who would be responsible for launch and inflight control? NASA Headquarters placed Huntsville in charge of configuration changes during launch operations. Debus was assigned mission responsibility through earth-orbital insertion. He then turned over Pegasus direction to a representative from the Headquarters Office of Advanced Research and Technology.⁴⁹

As the manufacture of the SA-9 booster progressed more rapidly than the SA-8, the next two Saturn shots were fired out of sequence; the SA-9 launch preceded SA-8 by three months. Problems with the Pegasus satellite delayed the erection of SA-9 until late October 1964. Once operations were under way, the launch team experienced little difficulty. SA-9 roared off its launch pedestal on 16 February after two technical holds: one involved the recharge of a battery in the Pegasus; the other came when the Eastern Test Range’s flight safety computer suffered a power failure. Pad damage from the rocket exhaust was described as “the lightest of any to date."⁵⁰ There was some water damage, however, from a broken torus ring. The ensuing cascade of water flooded the launcher and adjacent electrical support equipment.⁵¹

Contractor team dominated LC-37 during launch preparations for SA-8. The operation marked Chrysler Corporation’s assumption of responsibility, under broad guidance, for first-stage operations. The company’s launch team also participated in overall space vehicle testing. Douglas officials directed S-IV stage checkout, IBM conducted tests on its instrumentation unit, and Bendix Corporation provided ground support. After 86 days of space vehicle checkout, SA-8 launched Apollo boilerplate 26 (with Pegasus 2 inside) on a successful 25 May flight.⁵²

The SA-10 operation was conducted in haste. NASA officials had decided to begin LC-37 modifications for the Saturn IB rocket in August. If Kennedy Space Center could not launch the rocket by 31 July, its flight would have to come after the IB series. Under the pressure of this deadline, Chrysler and Douglas undertook 24-hour operations.

The SA-10 countdown proceeded without a technical hold, a near perfect finish to a highly successful series. The NASA-Saturn-contractor team had demonstrated the soundness of the Saturn I rocket and its launch facilities. A confident launch team looked forward to the next challenge: Saturn IB.⁵³