With the arrival of Apollo 12's spacecraft in late March 1969, four months before the first moon landing, Kennedy Space Center again had three Apollos in the operational flow. On 30 April Grumman mated the lunar module ascent and descent stages, while North American readied the command-service module for a cabin leak test in the altitude chamber. Launch vehicle stacking awaited the arrival of the S-IC first stage, which arrived from Michoud on 3 May and was placed on mobile launcher 2 four days later. Operations on Apollo 12 halted for two days while ordnance was installed in Apollo 11. The remaining Saturn stages were erected on the 22nd. At the operations and checkout building, a number of hardware problems delayed operations by a week. Although the Launch Operations office postponed until 30 June the transfer of the spacecraft to the vehicle assembly building, the launch team continued under a tight schedule. If Apollo 11 failed, KSC faced a possible September launch for Apollo 12.1
Testing went well during the next six weeks and the space vehicle stack was complete by 1 July. The successful lunar landing later that month relaxed the pace. After the splashdown on the 24th, General Phillips announced a 14 November launch of Apollo 12 to the moon's Ocean of Storms. Among the mission goals, NASA hoped to improve its landing techniques and secure low-orbit photographs of sites for further exploration. During extra-vehicular periods, the astronauts would gather lunar samples and deploy the first Apollo lunar surface experiments package.2
With the accomplishment of Apollo's primary objective, a number of key program officials decided to move elsewhere. In August 1969 Phillips left his position as Apollo Program Director to command the USAF Space and Missile Systems Organization. Rocco Petrone moved up from KSC to fill the vacancy in the Office of Manned Space Flight. The following month Rear Admiral Roderick O. Middleton vacated the Apollo Program Manager's Office at KSC to assume command of Cruiser-Destroyer Flotilla 12. In December Dr. George Mueller resigned as NASA's Associate Administrator for Manned Space Flight and was replaced by Dale Myers, an executive from North American Rockwell. That same month Albert Siepert announced his retirement from KSC.3
Petrone's departure from KSC brought Walter J. Kapryan to the post of Director of Launch Operations. A native of Flint, Michigan, and a graduate of Wayne State University, Kapryan had served as a B-29 flight engineer in World War II. In 1947 he had entered the field of hydrodynamic research at Langley Research Center in Virginia. When NASA absorbed Langley, Kapryan became a member of the Space Task Group. He came to the Cape in 1960 as a project engineer for Mercury-Redstone, worked for a time in Houston, and then headed Houston's Gemini Program Office in Florida. Kapryan came to Apollo in late 1966, first as Assistant Apollo Spacecraft Program Manager and then as Petrone's deputy. Although less imposing physically and less assertive in manner than Petrone, Kapryan enjoyed wide respect within Apollo program ranks. Middleton's successor, Edward R. Mathews, was a veteran of the Missile Firing Laboratory. As Chief of the Saturn IB Systems Office, Mathews had played an important role in LC-34 and 37 modifications. He had served as Deputy Apollo Program Manager since September 1967. Siepert's duties as Deputy Director for Center Management were taken on by Miles Ross when the latter became Deputy Center Director in June 1970. Fortunately there was little turnover during the remainder of the program.4
Apollo 12 rolled out in the early daylight of 8 September. The prime crew for the mission - Commander Charles Conrad, Command Module Pilot Richard Gordon, and Lunar Module Pilot Alan Bean - joined hundreds of other spectators. During September and October, the checkout proceeded in routine fashion. In the local jargon, it was a nominal operation. The countdown demonstration test ended on 29 October without incident, although rain and high winds stormed through the complex at simulated liftoff.5
The launch team started precount procedures one week before launch day. The 70 hours of activities moved along smoothly until Wednesday, 12 November. That morning technicians began filling the service module's liquid hydrogen tanks, which fed gaseous hydrogen to the spacecraft's fuel cells. There the hydrogen mixed with oxygen to provide electrical power and drinking water. Within minutes the North American test team knew it had a problem: one tank was not chilling down. When the team stopped the hydrogen flow, the fuel level dropped off rapidly. A crew member, looking through a panel window, detected frost on the tank. It was found that a leak in the outer shell had destroyed the vacuum insulation. Less than 40 hours remained on the countdown clock, and the problem was a new one for the North American crew at Merritt Island. After consulting with the Manned Spacecraft Center, John Williams, Spacecraft Operation Director, decided to replace the faulty tank with its corresponding unit from Apollo 13. Judging from experience at Downey, there was ample time for the operation. If the replacement could not be accomplished within the remaining hold time, KSC would delay the launch one month. The exchange involved removing an access panel and the cryogenic service lines leading through the panel, disconnecting a series of cryogenic feed lines and electrical connections between the tank and the hydrogen subsystem shelf, exchanging tanks, and refastening all the parts. The North American crew worked deliberately since spacecraft power was on, but still managed to complete the work within 24 hours. Meanwhile Launch Operations rescheduled the spacecraft cryogenic loading for Thursday morning at T-17 hours.6
The launch team had planned one other major change in the countdown - the installation of the fuel capsule that would provide power for the package of experiments to be left on the lunar surface. The experimental instruments received power from a small (45 centimeters high, 40 centimeters in diameter) atomic generator. The 3.8 kilograms of plutonium 238 that fueled the generator rode to the moon inside a graphite cask. Understandably, the plutonium was one of the last items placed aboard.7