THE FIRST LM

In mid-1966 Sam Phillips had hoped that AS-206 would be able to launch LM-1 in April 1967, and Kurt Debus, estimating that it would take 6 months to check out the spacecraft, had asked Grumman to send it to the Cape in September 1966. But it was delayed by manufacturing issues and combustion instabilities in the ascent engine. Nevertheless, AS-206 was erected on Pad 37 in January 1967 in the expectation of launching in April. However, because the AS-204 launch vehicle on Pad 34 had not been damaged by the fire that destroyed the Apollo 1 spacecraft, on 20 March it was reassigned to LM-1. Accordingly, by 11 April AS-206 had been returned to storage and AS-204R – as this was redesignated – erected in its place. In the absence of the spacecraft, Grumman built a plywood mockup on the pad for facilities verification.

On 12 May George Low confided to headquarters that although Grumman had promised to deliver LM-1 in June, he was sceptical. John J. Williams headed a 400- man operations team at the Cape. After the arrival of the ascent and descent stages on 23 June, LM-1 was mated on 27 June. However, the initial examination identified a significant number of departures from specification. On 26 July Carroll Bolender was reassigned to Houston as ASPO’s LM Manager. LM-1 was de-mated in August to repair leaks in the ascent stage. After another leak developed in September, it was de-mated and a number of items extracted for return to Grumman. After the testing was finally completed, the spacecraft, minus its legs, was mechanically mated to the launch vehicle on 19 November and a nose cone fitted in place of the absent CSM. The flight readiness tests were finished in late December. The cabin closeout was on 18 January 1968, during the countdown demonstration test. Loading the hypergolic propellants into LM-1 was delayed by procedural issues, but the ensuing tests ended on 19 January.

The terminal countdown began on 21 January, at T-10 hours 30 minutes. The spacecraft went onto internal power at T-42 minutes and, several hours later than planned, AS-206 lifted off as Apollo 5 at 22:48:08 GMT on 22 January 1968.

The S-IVB achieved an orbit ranging between 88 and 120 nautical miles, shed the nose cone and then splayed the four SLA panels. LM-1 was released at 000:53:50. After manoeuvring clear using its attitude control thrusters, the LM adopted a ‘cold – soak’ orientation, which its guidance system successfully maintained with a minimal engine duty cycle.

The mission plan called for two descent propulsion system manoeuvres, an abort staging, and an ascent propulsion system manoeuvre. The first manoeuvre was to occur on the third revolution and last 38 seconds. It would run at 10 per cent throttle for the first 26 seconds, then be concluded at full throttle. The thrust profile of the second manoeuvre was to be representative of flying a lunar landing, involving five phases over a total of 734 seconds. The abort staging sequence would be initiated at

full throttle, and was to include descent propulsion system shutdown and a ‘fire in the hole’ 5-second burn by the ascent propulsion system. The final burn was to run to propellant depletion and end the primary mission. The guidance system initiated the first descent propulsion system firing at 003:59:42 but the buildup of thrust did not satisfy the programmed velocity-time criteria, and the guidance system, sensing that the spacecraft was not accelerating as rapidly as expected, aborted the burn after just 4 seconds. In fact, this was a design feature, since on a manned mission it would allow the crew time to analyse the situation and decide whether to restart the engine to continue. In normal circumstances the engine would have fired with full tank pressurisation and achieved the desired thrust in 4 seconds, but in this case the tanks were only partially pressurised and it would have taken 6 seconds to build up thrust. The premature cutoff was merely the result of inadequate coordination between the guidance and propulsion teams, not a problem with the spacecraft. Mission Control sent a command to deactivate the guidance system in order to permit the remainder of the mission to be controlled from Earth using a preplanned sequence which would address the minimum requirements of the mission.

At 006:10:00 the onboard automatic sequencer initiated this program. It began by using the backup control system to control the vehicle’s attitude. In performing two burns in this mode, the descent engine gimballed properly and responded smoothly to throttle commands. But the short duration of the three descent propulsion system firings precluded a full evaluation of the thermal aspects of the supercritical helium pressurisation system. In abort staging, all system operations and vehicle dynamics were satisfactory for manned flight. The primary control system was then reselected to control the vehicle’s attitudes and rates. However, as this had been off during the abort staging sequence its computer program did not know of the change of mass resulting from this action and its computed thruster firing times were based on the mass of the two-stage vehicle and caused an extremely high rate of propellant usage. The final ascent propulsion system firing started at 007:44:13 and ran to thrust decay at 007:50:03. Since the attitude control system had by that time exhausted its own propellants, this burn was initiated with the thrusters drawing from the tanks of the ascent propulsion system. This continued until the sequencer automatically closed the interconnect valves, whereupon, with the thrusters starved and the ascent engine still firing, the vehicle started to tumble. The rates were soon of such a magnitude as to impede the flow of propellants to the engine, and helium ingestion induced thrust decay prior to propellant depletion. The vehicle had been in a retrograde orientation during the controlled portion of its final manoeuvre, and calculations indicated that it entered the atmosphere over the Pacific Ocean.

On 26 January the LM-2 flight requirements meeting determined that: (1) apart from minor anomalies, LM-1 had achieved all its flight objectives; (2) it should be possible to achieve the objectives for LM-2 either by additional ground testing or on a manned mission; and (3) it was not necessary to undertake additional unmanned flights to ‘man rate’ the LM. Grumman’s own view was that there should be two test flights, but the company relented after the review of the LM-1 data by the Manned Space Flight Management Council on 6 February. On 6 March NASA cancelled the shipment of LM-2 to the Cape. If AS-502 repeated the success of its predecessor, then AS-503 would indeed be manned, and hopefully be launched before the end of the year with CSM-103 and LM-3.