The Saturn/Apollo Stack - Assembling and Launching Content from the guide to life, the universe and everything

The Saturn/Apollo Stack - Assembling and Launching

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Project Apollo: The Beginnings | Mission Planning | Landing Site Selection | Earthbound Support Systems
Astronaut Selection and Training | The Saturn V | The Saturn 1B | The Apollo Spacecraft
Guidance and Navigation | Command and Service Modules | The Lunar Module
Assembling and Launching | Pathfinders | The Early Missions | Apollo 11, The First Landing
The Intermediate Missions | Apollo 15 Exploration | Apollo 16 Exploration | Apollo 17 Exploration
Skylab and Apollo-Soyuz | Conclusion

The Saturn S-IC booster and the second stage S-II were both delivered to the Kennedy Space Centre (KSC) in Florida by sea-going barges from their respective manufacturers. The third stage S-IVB and the Apollo spacecraft were delivered by air in modified cargo aircraft irreverently referred to as the 'Pregnant Guppy'. The Apollo spacecraft modules were passed to the Manned Spacecraft Operations Building (MSOB) where they were connected up to Acceptance and Checkout Equipment (ACE) for final testing. The three individual stages of the Saturn launch vehicle were each passed directly to the Vehicle Assembly Building (VAB) for checkout and stacking.

Acceptance and Final Testing (MSOB)

The acceptance testing by NASA of the Apollo spacecraft from its manufacturers, was carried out under clinically clean conditions in the MSOB. Each spacecraft was linked to ACE computers and underwent tests that duplicated each phase of the mission it was to perform. They were also subjected to leak tests in vacuum chambers simulating altitudes of 200,000 feet. The complete mission was simulated several times in the course of the checkout and on successful completion the LM's ascent and descent stages were mated together for the final time and assembled in its adapter housing. The CSM was then assembled to top of the adapter housing, ready to be passed to the VAB for final mating with the Saturn launch vehicle.

The stacking process began with a mobile crawler that picked up a mobile launch pad and a Launch Umbilical Tower (LUT) and placed it in position in one of the four VAB assembly bays. The crawler was powered by two 2,750 horsepower diesel engines driving four caterpillar tracks, each link in the tracks weighing one ton. Each of the three stages were then mated vertically on the mobile launchpad and connected to the lower umbilical supply arms of the tower. The bottom S-1C stage was held in place by up to twelve pull-through bolts and four explosively operated, launch release clamps. All three stages and the instrument unit were connected to the umbilical tower for testing by the ACE computers prior to receiving the Apollo spacecraft. The Apollo spacecraft in its adapter housing was then mated to the top of the Saturn stack and connected to the LUT through which its systems could be again tested.

Roll Out to Launch Pad

On completion of construction, and when ready for launching, the complete Saturn/Apollo stack would begin its journey to the moon at a stately one mile per hour on its mobile crawler to the launch site three miles away. The VAB and the launch sites are connected by a crawlerway constructed to support the combined weight of the spacecraft, mobile launchpad, tower and crawler. During its journey and when climbing onto the raised launch apron, the upright stack was controlled by a level sensing device which kept it vertical to within ten seconds of arc.

At the end of its run the stack was centred over a 50ft deep flame trench by the crawler, where the Saturn's exhaust plume would be directed at a vee-shaped flame deflector in the trench to split and direct it sideways. As the S-IC engines ran up to full power, a water deluge of up to 50,000 gallons per minute was directed into the trench to cool the exhaust gasses and damp down their sonic vibration. Finally, an access gantry, the Mobile Service Structure (MSS), the height of the moonship stack, was brought up to the spacecraft, opposite the LUT, to provide all round access. The stack would then be connected up to the Launch Control Centre (LCC) computers.

Final tests and loading of Apollo spacecraft gasses, ordnance and cryogenic fuels preceded the commencement of the launch final countdown at T minus 28 hours. Removal of the MSS was completed at T minus 10 hours. After a built in hold of the countdown at T minus 9 hours, chilling and loading kerosene, liquid oxygen and hydrogen to the Saturn launch vehicle began, supplied from storage tanks adjacent to the site which were linked to the spacecraft through the LUT. The crew took their positions at T minus 2 hours 40 minutes and the firing command to the automatic sequencer for engine ignition given at T minus 3 minutes 6 seconds. Engine ignition commenced at T minus 8.9 seconds and lift-off at T minus 00:00. Some eight seconds after lift off, just after the stack cleared the launch tower, the responsibility for the conduct of the flight transferred from Kennedy Space Centre launch control to the Mission Control Centre (MCC) at Houston, Texas.

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