The Launch of SA-1
Prelaunch preparation began at 7:00 a.m. on 26 October 1961. Mechanical Office tasks that morning included inspection of the high pressure gas panel, cable masts, and fuel masts; ordnance installation; and preparation of the holddown arms. At 12:30 p.m., Thomas Pantoliano's 12-man propellants section checked out the RP-1 fuel facility while Andrew Pickett's team pressurized the helium bottle. RP-1 loading began an hour later. The propellant team filled the launch vehicle's tanks to the 10% level, using a slow, manual procedure of approximately 750 liters per minute to check for leaks. A leak in the fuel mast vacuum breaker was easily repaired, and at 2:30 p.m. the launch team cleared the pad for the automatic "fast fill" operation. Fuel flowed into the launch vehicle at 7,570 liters per minute, reaching the 97% level in about 35 minutes. The propellants team then reverted to the "slow fill" procedure. As the design of the Saturn included a fuel drainage system, Pantoliano's crew placed 103% of the required RP-1 aboard the Saturn. Just before launch, the propellants team would take a final density reading and drain sufficient kerosene to achieve the desired level.35
The ten-hour countdown started at 11:00 p.m. as LC-34 switched to the Cape's emergency generating plant. This facility supplied the launch team a current relatively free of the fluctuations common in commercial power. The Saturn's electrical circuits and components began warming up when vehicle power was applied at T-570 - 570 minutes before launch time exclusive of holds. Five minutes later the measuring panel operator turned on the eight telemetry channels, A series of calibration checks followed. At T-510 range and launch officials initiated an hour of radar checks.36
Loading of liquid oxygen started after 3:00 a.m. on the 27th (T-350). The Saturn's LOX tanks were 10% filled to check for leaks in the launch vehicle or in the 229-meter transfer line, as well as to precool the line for the fast flow of super-cold LOX. While the automatic fast fill rom the 473,000 liter LOX storage tank employed a centrifugal pump, the 10% precooling operation relied on the pressure in the reservoir. The 10% level in the Saturn's tanks was maintained for the next four hours by feeding LOX from the 49,000-liter replenishing tank.37
Testing of command and communication systems began at T-270. The flight control panel operator activated the guidance system's stabilized platform, the ST-90, to check pitch, roll, and yaw response. Ten minutes later the network panel operator placed the vehicle on internal power to ensure that the Saturn's batteries functioned properly. Meanwhile other engineers conducted Azusa, UDOP , radar, and telemetry checks. The operation was over by T-255, and the launch vehicle was returned to external power.38
Two hours from the 9:00 a.m. scheduled liftoff, an unfavorable weather report prompted launch officials to call a hold. When the count resumed at 7:34 a.m., the launch team rolled the service structure back to its parking area, 180 meters from the rocket. The propellants team set up the LOX facility for fast fill at T-100. The order to clear the pad came 20 minutes later; the blockhouse doors swung shut at T-65. One hour from launch the pad safety officer gave his clearance and the propellants team initiated a 6.5-minute precool sequence, a slow fill to recool the main LOX storage tank line, which had not been in use for four hours. When the "Precool Complete" light flashed on, the LOX facility's pump began moving 9,500 liters per minute into the Saturn. In 30 minutes the tanks were 99% full. LOX loading changed over to the replenish system. An adjust-level drain* had already been made on the RP-1 tanks, bringing the fuel level down to 100%.39
Launch officials, concerned that a patch of clouds over the Cape might obscure tracking cameras, called a second hold at 9: 14 a.m. A northeast breeze was soon clearing the skies, and within half an hour the countdown resumed. During the last 20 minutes, the launch team made final checks of telemetry, radar, and the command network. Automatic countdown operations commenced at T-364 seconds. A sequencer or central timing device controlled a series of electrical circuits by means of relay logic; i.e., if event A occurred (e.g., opening a valve), the sequencer triggered event B, and so on through the required functions to liftoff. The sequencer monitored tank, hydraulic, and pump pressures; ordered a nitrogen purge of the engine compartment; and closed the LOX tank vents to pressurize the liquid oxygen. The Saturn vehicle switched to internal power at T-35 seconds. Ten seconds later the sequencer ejected the long cable mast. The pad flush command at T-5 seconds began a flow of water around the launcher base. At that time, a number of possible malfunctions (a premature commit signal, insufficient thrust in one or more engines, rough combustion, short mast failure, detection of fire, or voltage failure) could still cause the automatic programmer to terminate the countdown.40
Away from launch complex 34, Cape watchers gazed uncertainly at the Saturn rocket as the countdown neared completion, No previous maiden launch had gone flawlessly, and the Saturn C-1 was considerably more complicated than earlier rockets. LOD officials gave the rocket a 75% chance of getting off the ground, a 30% chance of completing the eight-minute flight. Although odds on a pad catastrophe were not quoted, launch officials acknowledged their vulnerability. With the construction of LC-37 barely begun, a pad explosion could delay the Saturn program a year. Critics had questioned the wisdom of the clustered booster design. Propellant pumps were supposedly reaching design limits and the Saturn C-1 had 16 pumps in eight engines. Local wags derisively referred to the SA-1 launch as "Cluster's Last Stand."41
Saturn backers, while expressing confidence in the rocket, were concerned about its launch effects. During test firings at Redstone Arsenal, residents 12 kilometers away had reported shattered windows and earth tremors. The launch team had set up panels and microphones at the Cape to register the Saturn's shock and sound waves. At the press site, 3 kilometers from pad 34, reporters were issued ear plugs as a precautionary measure. LOD officials had assured local residents that fears of the rocket were exaggerated. Still, everyone wondered what it would be like. The moment of truth came at 10:06 a.m. Contrary to popular belief, no one pushed a firing button to send SA-1 on its way. Launch came when the sequencer ordered the firing of a solid propellant charge. The gases from the ignition accelerated a turbine that in turn drove fuel and LOX pumps. Hydraulic valves opened, allowing RP-1 and LOX into the combustion chambers, along with a hypergolic fluid that ignited the mixture. The engines fired in pairs, developing full thrust in l.4 seconds. A final rough combustion check was followed by ejection of the LOX and RP-1 fill masts from the booster base. The four hold-down arms released the rocket 3.97 seconds after first ignition. SA-1 was airborne.
Liftoff of Saturn I. Note the long cable mast falling away on the right.
Spectators saw a lake of flame, felt the rush of a shock wave, and then heard the roar of the eight engines. Trailer windows at the viewing site shook in response to the Saturn's power. Yet for many of the thousands watching the launch, the roar was a letdown. Reporters thought the sound equaled an Atlas launch viewed at half the distance.** The Miami Herald headline the next morning read: "Saturn Blast 'Quieter' Than Expected."42
Although the Saturn's roar failed to meet expectations, the human noise at LC-34's control center was impressive. Bart Slattery, a NASA information officer, told reporters that when the rocket passed maximum Q (point of greatest aerodynamic pressure) at about 60 seconds into the flight, "all hell broke loose in the blockhouse." Kurt Debus's face reflected the happy sense of accomplishment hours later when he informed the press that it had been a nearly perfect launch.43
The success was particularly welcome to the Kennedy administration, coming at a time of high tension between the United States and the Soviet Union. The raising of the Berlin Wall had stunned the Western world in August 1961. President Kennedy had responded with a partial mobilization of U.S. reserve forces, but most political analysts considered the events a Russian victory. In late October, as the Soviet Union prepared to test a 50-megaton H-bomb, the President had proposed a massive fallout shelter program. On the day of the SA-1 launch, Russian tanks moved into East Berlin for the first time in several years.
The space race was an important element in a Cold War that threatened to turn hot. With the success of the Saturn booster, the United States had achieved a launch capability of 5.8 million newtons (1.3 million pounds of thrust). Space reporters were quick to point out the limits of the American success. The Soviet Union already had workable upper stages for their first stage. Furthermore, the current Russian tests in the Pacific would likely result in sizable booster advances. Despite these caveats, commentators agreed that SA-1 was an important step toward a lunar landing.44
* Establishing an exact ratio of RP-1 to LOX was important since simultaneous depletion of propellants at cutoff was desired. Flight data later indicated a 0.4% deviation in the RP-1 fuel density sensing system, 0.15% above design limits. Too much LOX (400 kilograms) and not enough RP-1 (410 kilograms} were therefore loaded. The error contributed to a premature cutoff 1.6 seconds ahead of schedule.
** Marshall Center scientists, after studying readings taken in nearby communities during launch, explained that weather conditions were such that sound was absorbed by the atmosphere. As a result, sound levels were less than those experienced during static firings at Huntsville.
37. MSFC, SA-1 Flight Evaluation, p. 10; MSFC, Countdown SA-1.
38. MSFC, Countdown SA-1, pp. 20-23.
43. Miami Herald, 28 Oct. 1961, p. 1 (UPI release).
44. New York Times, 27 Oct. 1961, p. 1; 28 Oct. 1961, pp. 1, 9.
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