When spacecraft problems in the spring of 1966 delayed the preparation of Apollo module 011, AS-203 became the second Saturn IB flight. The AS-203 carried no spacecraft; its primary purpose was to test the dynamics of liquid hydrogen in the weightlessness of space. On a lunar mission, the S-IVB stage would orbit the earth one and one-half times and then restart its J-2 engine to propel Apollo toward the moon. Marshall engineers wondered whether the ten tons of liquid hydrogen would settle to one part of the fuel tanks or slosh violently about. The S-IVB stage of the AS-203 was equipped with 83 special measuring devices and two television cameras to study the chilldown of the J-2 engine (the preliminary cooling of the propellant systems with small amounts of cryogenic hydrogen). The mission also tested IBM's new instrument unit. AS-203 was launched from pad 37B, which had been modified extensively since the SA-10 launch the previous summer.38
Chrysler technicians erected the S-IB booster on 19 April. On subsequent days the S-IVB stage, the instrument unit, and the nose cone joined the stack. The checkout soon bogged down in another epidemic of computer ills. Most of the blame was laid to cracked solder joints in the printed-circuit boards, the same defect that had troubled AS-201. By 24 May technicians had exchanged 2,000 printed boards and planned to remove 6,000 more. Other portions of the Saturn checkout proceeded on schedule. On 27 May Albert Joralan reported that S-IB measuring calibration was 70% complete; the calibration of the S-IVB and instrument unit stood at 60 and 87%.39
The month of June saw an unusual spectacle at the Cape - three Saturns looking skyward, and menaced briefly by a hurricane. Saturn 500-F stood on LC-39, AS-202 on LC-34, and AS-203 on LC-37. The simultaneous operations taxed KSC's propellant reserves, but essential needs were met.40
The AS-203 launch, originally scheduled for 30 June, was delayed by an Explorer launch and minor problems. It was almost scrubbed when one of the television cameras failed, but on 5 July the rocket achieved a virtually perfect orbital insertion. The remaining television camera operated perfectly, and apparently answered any questions about S-IVB's readiness to serve as the Saturn V third stage. In September Douglas Aircraft announced that the S-IVB stage had no serious unsolved technical problems.41
Computer problems also characterized the AS-202 operations at LC-34. Printed-circuit boards continued to frustrate Gruene's Launch Vehicle Operations Division and, after the AS-203 launch, KSC transferred all of LC-37's printed-circuit boards to LC-34. The change reduced the downtime of the RCA 110As considerably. Despite the launch vehicle team's misfortunes, NASA spokesmen cited spacecraft delays in postponing the AS-202 launch until after the 203 mission. Late deliveries of equipment and engineering orders plagued spacecraft operations. The patching of the ACE system (rerouting the electrical lines to various pieces of test equipment) was particularly troublesome. The spacecraft team found, to their sorrow, that Apollo 011 did not duplicate the 009 modules. The spacecraft team corrected most of the problems in three months and erected Apollo 011 on 2 July 1966. The countdown demonstration test began on the 29th and ran for one week. During that period, KSC also conducted two spacecraft emergency egress tests. The launch team completed the flight readiness test on 16 August.42 Alfred O'Hara, chief of the Saturn I-IB Operations Office, reported that all Saturn tests had been completed satisfactorily. Richard Proffitt, spacecraft test conductor, described the Apollo checkout as "a good clean test and we feel that we are 100 per cent ready."43
AS-202 lifted off on 25 August. A communications problem between Mission Control in Houston and a tracking ship in the Atlantic had caused the only significant delay in the countdown. In the final minutes, however, the launch team barely outraced hurricane Faith; the tropical storm shut down the Antigua tracking station 45 minutes after launch. AS-202's 93-minute suborbital flight covered 33,000 kilometers. Although the spacecraft splashed down 370 kilometers short of its target in the Pacific Ocean, the mission was judged a success. A design certification review board, meeting in September, declared that Apollo-Saturn IB could now be used for manned flight.44
The Apollo-Saturn IB launches of 1966 represented important gains for NASA's launch team. LC-34 and LC-37, testbeds for automated checkout, were found wanting. In the 20 months between AS-201 and AS-501, KSC corrected the major automation problems. Without these trial and error advances, AS-501, the toughest launch in Apollo's history, would have been far more difficult.