Moonport: A History of Apollo Launch Facilities and Operations|
The achievements of Apollo 8 obscured some of the limitations of that flight. Most important from KSC's point of view, Apollo 8 was not a complete moon-landing vehicle. A test article had done duty for the real lunar module. In the launch vehicle, the S-II stage had carried extra insulation, and research and development instrumentation had been flown on all stages. Final confirmation of the LC-39 launch procedure would have to wait on a fully operational Apollo-Saturn. Apollo 9 (AS-504) would bring the space vehicle much closer to operational status. It would be the first test of the mated command-service and lunar modules. The 10-day mission in earth orbit would check out combined spacecraft operations and run the lunar module through a series of solo flights.1 Some viewed the mission as a relatively mundane exercise in earth orbit except for the checkout of the lunar module's docking capabilities; but in General Phillips's words, Apollo 9 was "certainly one of the most vital missions that we've had in our mission sequence [and the risks] a little greater than the risks which we knowingly accepted in committing the Apollo 8 mission."2 Moreover, Apollo 9 was to become the standard for processing subsequent Apollos through KSC.
Early schedules had listed Apollo 9 as the first manned Saturn V mission after three unmanned development flights. In the letter of 19 August 1968, which removed the lunar module from the Apollo 8 configuration, the Apollo 9 mission was redefined as a test of the lunar module in earth orbit. The crew slated for a later flight - James McDivitt, David Scott, and Russell Schweickart - was moved up to Apollo 9, and launch date was set for late February 1969.3
Launch operations began in May 1968 with the arrival of the S-II stage - first on hand this time after holding up three previous Saturn V missions. In August the North American team began modifying the S-II stage, not without complaint that Huntsville and the home office were not providing adequate direction. This dereliction, the daily status report for 28 August warned, might once again delay the high-bay testing of the S-II. X-ray reports in mid-September gave the forward skirt splices a clean bill. At the same time the team made extensive changes in the propellant utilization and instrumentation systems to accommodate the S-II's new engines, which had been uprated to nearly one million newtons (230,000 pounds of thrust). Thanks to its early arrival and the team effort, the S-II stayed close to schedule. The third stage S-IVB arrived 12 September, followed in late September by the instrument unit, flight control computer, and S-IC first stage with its pogo modification. After inspection in the transfer aisle, the first stage was erected on 1 October; stacking of the entire vehicle was completed on 7 October. Erecting launch vehicles was becoming routine. Testing of the Saturn systems progressed according to plan during October, and faulty accumulators on two swing arms were replaced without delaying the schedule.4
Early in November a problem developed that involved both the vehicle and the ground support equipment. During the S-IC fuel prepressurization leak and functional test, a significant amount of RP-1 was spilled in the mobile launcher. Pressure in the Saturn fuel tank had forced fluid from the engine supply and return lines into a hydraulic pumping unit reservoir. The back pressure caused an overflow. An additional failure of a check valve on the gaseous nitrogen purge line allowed RP-1 fuel to back up into the electrical system of the hydraulic pumping unit. Accumulators from launcher 3 were borrowed for use on launcher 2. This type of problem illustrates the close interrelation of the rocket and ground support equipment. In effect, they formed a single unit, and malfunctions in one frequently caused damage to the other.5
The boilerplate spacecraft was removed from the stack on 2 December and the flight spacecraft replaced it the following day. At this point, the countdown demonstration test and launch countdown for Apollo 8 halted the testing of Apollo 9. The preliminary flight program tapes for the launch vehicle arrived at KSC on 20 December and the electrical mate of the space vehicle was finished six days later. After a plugs-in test in the assembly building on the 27th, ordnance installation was completed on New Year's Eve. The processing of Apollo 9 was on the schedule set in September and the space vehicle was ready for the trip to the pad. Despite problems, both vehicle and launch complex schedules had been maintained in a way hitherto unknown for Saturn V. Experience was beginning to show results.6