Concise description of the Apollo Launch Operations

The whole rocket was a complex machine; the LUT and the two-storey-high grey launch platform contained a lot of equipment to monitor the numerous systems in the stack and to prepare the rocket for flight. Figure 2 is a functional system diagram in which it is shown how the Saturn V-Apollo stack was monitored from one of the three firing rooms in the LCC (Launch Control Centre) and from two control rooms in the MSOB (Manned Spacecraft Operations Building).

The first stage (S-IC stage) was running on kerosene and liquid oxygen. Both the second stage (S-II stage) and the third stage were running on liquid hydrogen and liquid oxygen.

The swing arms between the LUT and the launch vehicle were part of the Ground Support Equipment (GSE). The swing arms were used for propellant loading, all kinds of electrical connections, environmental control and vent lines for the fuel tanks filled with liquid hydrogen. The tail service masts and the swing arms nr. 4 through 8 were retracted at lift-off.

This hazardous gaseous hydrogen was burnt in special burn ponds at some distance from the launch pad. The tanks filled with liquid oxygen were vented through vent valves of the three stages in the open air to keep the tank pressure within limits.

The two-storey-high launch platform housed an impressive set of equipment to control the equipment of the launch umbilical tower. A computer system was part of that equipment, which also contained a so-called auto-sequencer, a computer program to control the countdown sequence during which hundreds of parameters of the launch vehicle and of the launch umbilical tower were checked and commands were sent to various systems according to a pre-determined sequence of which the "ignition" was the final command.

n this diagram is shown how the launch vehicle (Saturn V) and its ground support equipment were monitored and controlled from the firing room. Most of the ground support equipment was housed inside the launcher platform. The propellant storage tanks (for LOX, LH and RP-1) were located at the outer perimeter of the 1 square kilometer launch pad.

Spacecraft systems and systems of the Lunar Lander were in large part monitored from two control rooms in the Manned Spacecraft Operations Building (MSOB) located at the KSC Industrial Area about 6 km from the LCC.

Most consoles in the control rooms were used to control various systems remotely. But some consoles were interconnected with an RCA-110A computer system to initiate various test routines consisting of pre-programmed sequences of commands. The Saturn V had 7 groups of systems which were controlled remotely:

1. The Apollo Command Module;
2. the Apollo Service Module;
3. the Lunar Module (ascent and descent stages);
4. the Saturn V Instrument Unit;
5. the S-IVB stage;
6. the S-II stage and
7. the S-IC stage.

The equipment designations A through F correspond to the designations in figure 3.

The equipment designations A through F are corresponding to the equipment designations in figure 1.

On the floor plan it can be seen that for monitoring and managing the Saturn V launch vehicle, the managers and the engineers were located in separate areas. A similar arrangement has been set up for monitoring the spacecraft (Command Service Module and the Lunar Module). However, only the management was present in the firing room (area A); the engineers were located in Acceptance Checkout Equipment (ACE) Control Rooms. These rooms were part of the Manned Spacecraft Operations Building (MSOB) at the KSC industrial area some 7 km away. The floor plan of these ACE control rooms is shown in figure 4.

ACE stands for Acceptance Checkout Equipment. The equipment has been designed for automated acceptance testing of Apollo spacecraft and enabled a team of testers to run through numerous test cycles on various systems of the spacecraft. A particular test run comprising various tests could be initiated by the press of a button. Test results were displayed analogously or digitally and were automatically stored on magnetic tape or recorded on chart recorders. When the spacecraft had passed the acceptance test, it was declared fit for mating with the Saturn launch vehicle in the Vertical Assembly Building (VAB).

There were two pairs of these control rooms; they were located on the third floor in the south wing of the Manned Spacecraft Operations Building (MSOB).
Each ACE Control Room was part of an ACE station. Such a station consisted of a control room, a computer room for processing data and commands from the control room and a terminal room to interface with the transmission system.
For more information about the ACE Control Rooms, click here.

The two pairs of these control stations allowed NASA to conduct testing at the KSC on two pairs of Apollo spacecraft (CSM + LM) simultaneously.
One pair of spacecraft could be located in the Vertical Assembly Building (VAB) for integration with the launch vehicle or at the launch pad for launch preparations. At the same time, testing in the MSOB on another pair of spacecraft for the next mission could be conducted because of this second pair of control stations.

When a pair of spacecraft (CSM + LM) was checked out and had been transported to the Vertical Assembly Building (VAB) to be mated with the Saturn V launch vehicle, it went through a sequence of prelaunch phases (see figure 5) from then on. With this sequence the highly complex Saturn V-Apollo stack was prepared for launch methodically to gradually bring it into a state of "ready for flight". During this process the stack went through a series of test cycles on various systems. During these test cycles systems began fulfilling their purpose for the first time, or systems began operating under different circumstances because of the constantly changing operational state of the stack. It was therefore paramount that the Apollo spacecrafts remained connected to the ACE control rooms for monitoring and testing when the stack was in the VAB or at the launch pad.

A global overview of the prelaunch sequence. The assembly of the Saturn V with the spacecrafts on top was a delicate well choreographed process. The various tests on all the complicated systems were conducted in parallel with the assembly process.

The phases F, G and H were the pivotal phases leading up to the launch and were therefore rehearsed in a Count Down Demonstration Test (CDDT) to ascertain the launch readiness of the launch vehicle, spacecraft and ground support systems.

In the final 3 minutes all checks were conducted by the "auto sequencer". At T-50 sec all systems of the Saturn V launch vehicle switched from external electrical power to internal (battery) power.

1. Saturn V Flight Manual SA-503
   George C. Marshall Space Flight Center
   MSFC-MAN-503
   1 November 1968

2. Countdown to a Moon Launch
   Preparing Apollo for Its Historic Journey
   by Jonathan Ward
   Springer, 2015