A lunar module arriving at KSC aboard the Super Guppy, June 1967.
The uncertainty about the Apollo 8 mission, temporarily relieved by the progress on Apollo 6's deficiencies, reappeared in June when KSC began testing lunar module 3. Although it was to have arrived in flight-ready condition, KSC soon found out otherwise. The ascent and descent stages were delivered separately during the early part of June. Several leaks appeared during early tests of the ascent stage; one of them required a redesign and valve change. Early in July, a damaged flight connector in the rendezvous radar of the spacecraft caused a delay in its final installation. A week after this, there was a meeting at KSC of Houston, Grumman, and KSC officials to resolve the modification requirements. KSC estimated that it would take four days to complete the approved modifications prior to altitude chamber operations. An additional three to four days might be required if other pending modifications were approved. While work proceeded around the clock, engineers began a combined systems test for the spacecraft on 17 July. Problems with the radar, guidance, and communications systems delayed completion of the test for three days.54
During July, KSC was also investigating an electromagnetic interference problem in which the rendezvous radar locked onto the telemetry signal. Filters sent from the Grumman plant did not correct the problem. Attempts to tune the coaxial connection between the radar dish and the electronics package lessened the interference with the telemetry system, but resulted in a new interference with the abort guidance system. On 2 August when the spacecraft internal systems were activated, electromagnetic interference increased and further investigation began. As George M. Low later recalled, it was about this time that a circumlunar mission without a lunar module first appeared as a real possibility. Difficulties encountered at KSC were having their impact on decision-making at headquarters.55
The S-II second stage had gone immediately to the low-bay transfer aisle after its return on 27 June. Between 1 and 11 July, the augmented spark igniters in the five engines were changed. When the second stage was erected on 24 July, the third stage was still undergoing modification. Forecasts that the instrument unit's flight control computer would not arrive on time threatened the schedule. Between delays in the delivery of launch vehicle hardware and difficulties with the lunar module rendezvous radar, the period of late July and early August was critical. Without a firm decision from headquarters, KSC could not move effectively, and difficulties at KSC tended to preclude firm decisions.56
At a Management Council Review in Houston, 6-7 August, Low presented the details of the lunar module problems and asked the Houston mission director, Christopher C. Kraft, to look into the feasibility of a lunar orbit mission without a lunar module. Low noted that the KSC work schedule was currently headed for a January 1969 launch and that insistence upon the use of lunar module 3 could result in a delay of up to two months. At a second meeting on 9 August, Kraft reported that the lunar orbit mission was feasible. Debus indicated that KSC could support such a launch as early as 1 December. Only two items remained open: the location of a suitable substitute for the lunar module and the approval of the Administrator, who was overseas at the time. Within three days after the meeting, the command and service modules for Apollo 8 had arrived at KSC.
At a meeting in Washington on 14 August, NASA substituted a test article for the lunar module. Since the circumlunar mission depended on KSC's ability to support a 6 December launch, Debus was asked to assess the launch team's chances. The KSC director replied that he had no technical reservations. Although Mueller expressed a reluctance to decide before Apollo 7 results were evaluated, he conceded the necessity of doing so. The overall review of the circumlunar mission plan resulted in an informal "go." KSC's response was immediate and positive: the following day, the spacecraft facility verification vehicle was erected on the instrument unit.
Administrator Webb agreed on 17 August to man Apollo 8 for an earth-orbital mission, but postponed the decision on a circumlunar mission until after the Apollo 7 flight. The launch of Apollo 8 was set for 6 December. On 19 August, General Phillips announced the earth-orbit mission to the press in Washington. He ascribed the change to the problems with the lunar module, then six weeks behind schedule.57 To expedite prelaunch operations for Apollo 8, Phillips relieved KSC of much of the burden for hardware modification. The appropriate development centers were given the responsibility with the understanding that only changes necessary for crew safety would be accomplished.58
In mid-September KSC completed the first ten parts of the launch vehicle malfunction test satisfactorily; part 11 was scrubbed because of a failure in the RCA 110A computer. A modification of the computer in the launch control center delayed the plugs-out test until 18 September. At this point the spacecraft was approximately 5 days behind the 10 September schedule.59
NASA conducted a delta design certification review on 19 September by means of a teleconference. Since Boeing had not yet completed the testing and analytical work associated with pogo, Phillips asked MSFC to recommend a date in November for the final review of the Saturn V. Two days after the spacecraft was added to the launch vehicle stack, Apollo 8 rolled out to the pad on 9 October.60 During the remainder of the month, the launch team conducted a series of space vehicle tests. The flight crew participated in several, such as verifying the performance of the command, control, video, and optical systems in support of the abort advisory system. They were also active in emergency egress training. Unlike earlier programs in America's manned space effort, the crew did not spend a great amount of time with the actual flight vehicle.61
The Apollo 7 mission ended with splashdown on 22 October. Six days later, NASA outlined the steps that would lead to a final decision on the next manned Apollo during the week of 11 November. Dr. Thomas O. Paine, acting Administrator, said: "The final decision on whether to send Apollo 8 around the moon will be made after a thorough assessment of the total risks involved and the total gains to be realized in this next step toward a manned lunar landing. We will fly the most advanced mission for which we are fully prepared that does not unduly risk the safety of the crew."62 On 12 November NASA made its decision public - Apollo 8 would fly a lunar-orbital mission beginning 21 December.63