Apollo/Saturn Mobile Launcher

Written by: Ross B Tierney

"Near the horizon, a gleaming silver tower bathed in floodlights,
stood the last of the Saturn Vs, for almost twenty years
a national monument and place of pilgrimage."

-2001, A Space Odyssey, Sir Arthur C. Clarke.

Basic Structure:

Apollo 4 Rollout - 19th June 1967
Each of the three Mobile Launchers stood a massive 490ft. 6in. tall, from ground level to the high-point at the top of the lightning-mast. The structures consist of four main parts:- The Hammerhead Crane on the top, the Launch Umbilical Tower (LUT), the 2-story grey Launcher Base and six 22ft. tall support legs holding the whole structure off the ground.

The LUT itself is the red 380ft tall tower, with a total of 18 levels. The first two levels are separated vertically by 30ft, and all of the others by 20ft. Each level is referred to by their height, such as; ‘level 30’, or ‘level 220’. Attached to the side of this structure are the various Service Arms allowing access from the LUT to the rocket itself and for connecting fuel lines and direct electrical connections. On top of the 380ft. LUT is the heavy-duty crane, capable of full 360 degree rotation and able to support a maximum of 25 tons.

The 25ft. tall grey Launcher Base is 160ft. 4in. long and 135ft. wide. It basically consists of two internal floors, ‘A’ and ‘B’, and a great deal of very heavy duty steel girders to support the great weight of the LUT and a fully fuelled Saturn-V rocket.

There is a large 45ft. square-shaped hole through the base, immediately under the rocket called an Exhaust Chamber. This blast-shielded chamber allows the engine exhaust to pass through to flame deflectors located down in the concrete Pads. These are used to divert the hot exhaust gases safely away from the rocket and ML. Around the top of this chamber are four Hold Down Arms which support the entire weight of the Saturn-V, and held it firmly in place until the moment of launch. There were also three umbilical connections, called Tail Service Masts, at the bottom of the rocket to provide liquid and electrical lines to the first stage of the Launch Vehicle. This part of the ML structure was simply referred to as the ‘Launcher Base’ of the ML, but when they were later modified for Shuttle operations around 1980, they were officially named Mobile Launcher Platforms (MLP).

Six large legs, called Mount Mechanisms, support the Mobile Launcher exactly 22ft off the ground to allow NASA’s famous Crawler Transporters access underneath to lift the ML’s up for transportation between the Vehicle Assembly Building (VAB) and the Pads. These Mount Mechanisms also guarantee very precise alignment of the ML’s at the Pads and inside the VAB. Four more removable hydraulic pedestals, called Extensible Columns, are used out at the pad itself to help distribute the extra weight of the fully fuelled Saturn-V rocket, which tipped the scales at over 3 million kg (6,600,000 pounds) before launch.

Launch Complex 39:

ML-1 & ML-2 Under constreuction - 19th July 1964
All three of the Saturn-V Mobile Launchers were built between July 1963 and March 1965. Throughout their service lives they were continually modified to suit the different missions. In total, they were used for only 17 launches from the first Saturn-V launch of the unmanned Apollo 4 through to the Saturn-1B launch of the Apollo-Soyuz Test Program spacecraft.

The whole area of Launch Complex 39 was custom-designed for the preparation and launching of the gigantic 102 meter tall Saturn-V rockets to take men to the moon.

At one end of the complex is the cavernous VAB – still to this day one of the largest buildings on the face of the Earth. It was built between November 1962 and June 1965. This vast building was designed to be capable of preparing up to four of the 363ft. tall Saturn-V vehicles all at the same time. In the end, only three of the four high-bays were equipped to handle the launch vehicles and the fourth was used for storage. The building measures 218 meters (716 ft.) in length, twice the length of an American Football field, and 158 meters (518 ft.) in width. It stands 160 meters (525 ft.) tall. To put that into perspective, the entire Statue of Liberty would comfortably fit through any one of the four inverted-’T’ shaped doors on the sides.

VAB & all three ML/LUT's under construction - 5th January 1965

VAB, Crawlerway & Pads during Apollo 11 Rollout - 20th May 1969
On the south-eastern side of the VAB is the smaller, somewhat ‘squat’ four-story Launch Control Center (LCC), which boasted four separate firing rooms on the top floor. These consisted of four Launch Control rooms, Test Conductors Platforms, Visitors Galleries, Offices and vast computer rooms. Other floors contained telemetry equipment, cafeterias and numerous other facilities for the launch complex.

The Crawlerway connects the VAB with the two launch pads out near the coastline. It too is built on a scale rarely ever seen anywhere. Started in November of 1963 and completed nearly two years later in August 1965 it basically consists of two lanes from each doorway of the VAB out to the launch pads. The Crawlerway splits about a mile from Pad A to afford access to both Pads. Each of the gravel covered lanes span 12 meters (40 ft.), with a total width measuring 39 meters (90 ft.). The enormous 8,165,000 kilogram (18 million pound) assemblage of Crawler Transporter, Mobile Launcher and Saturn Launch Vehicle required a very special low-friction surface to be found. Engineers chose Alabama river gravel for its particular combination of qualities and it is still in use today.

LC-39A under construction - 1st January 1965
The two Launch Pads themselves, LC-39A and LC-39B, were built between November 1963 and October 1965. The identical pads are each roughly octagonal in shape and cover 130 hectares (half a square mile). The 18 meter (59 ft.) wide flame trench at the pads could not be sunk below ground level as the water table around the cape is very close to the surface. This required that the pads themselves be raised up by 13 meters (42 ft.). The distinctive concrete ‘hill’ in the center of the pads was the result. Surrounding the pads are lots of ancillary equipment used for fuelling and pre-flight maintenance.

AS-500 at LC-39A (Pad B in the background) - 1st January 1966
When the Mobile Launcher is moved to the pad it aligns very carefully with all of the electrical and propellant lines for all the different stages and systems. The fuelling process for a Moon mission was very complex indeed. The first stage of the vehicle used RP-1 fuel (a highly refined form of kerosene) and liquid Oxygen (LOX) oxidizer at –138 degrees Celsius (-297 Fahrenheit). The second and third stages also used cryogenic liquid Oxygen but used liquid Hydrogen fuel at –253 Celsius (-423 Fahrenheit) instead of RP-1. Other hypergolic fuels (fuels that chemically ignite on contact and do not require artificial ignition) such as Nitrogen tetroxide (AKA Aerozine-50) and Monomethyl hydrazine were also utilised.

The final piece of major hardware at LC-39, completed in late 1966, was the Mobile Service Structure (MSS). This tall tower consisted of a lattice-work assembly approximately 125 meters (410 ft.) tall, with a base approximately 41 meters (135 ft.) by 40 meters (132 ft.) across and tipping the scales at 4,800,000 kilograms (10,500,000 pounds).

MSS in background during Apollo 6 Rollout - 6th February 1968
The MSS was moved around by the Crawler Transporters, just as the ML was. Near the top of the structure were five complex work platforms. When the MSS locked against the Mobile Launcher it would engulf the entire top of the Launch Vehicle and provide complete 360 degree clean-room access to the Command Module, Service Module and Lunar Module out at the Launch Pad. When not in use, the single MSS stood half-way down the Crawlerway at the point where it splits from Pad A to Pad B.

Mobile Launcher in Service

MSS approaches Apollo 8 at LC-39A - 15th August 1963
Mobile Launcher number 1 first saw service in 1966. In preparation for the first Saturn-V launch, a full engineering mock-up Saturn-V stack, called a Facilities Verification Vehicle (FVV), and designated vehicle number SA-500F. SA-500F was never launched, It was rolled out of the VAB on 25th May 1966 to Pad LC-39A in order to test all the procedures and equipment which would later be required during the Apollo flights. After use it was disassembled and various parts used for testing elsewhere.

The unfortunate thing about SA-500F was that this non-flight example of the hardware was used by most model manufacturers as the primary source material – however it was not the same as the eventual flight examples. Many parts, especially the colour scheme, were not the same as eventual flight hardware.

On 19th June 1967, the first flight-ready Saturn-V (SA-501) launch vehicle was rolled out to Launch Complex 39A onboard ML-1. Nearly five months later on 9th November 1967 the unmanned Apollo 4 mission was launched successfully.

Apollo 6 (SA-502) was launched on 4th April 1968 and was again unmanned. This launch was the first use of the newly commissioned ML-2. The Tail Service Masts (TSM) were modified for this launch as they had suffered severe damage during the previous launch. The new design was kept for all subsequent flights of the Saturn-V’s.

The crew of Apollo 8 Frank Borman, James A. Lovell, Jr. and William A. Anders became the first people to ever see the other side of the Moon with the naked eye. The rocket (SA-503) was rolled out of the VAB to LC-39A on 14th August 1968 and the 6 day mission was launched four days before Christmas on 21st December 1968.

Apollo 9 climbing the ramp to Pad A (people in foreground) - 3rd January 1969
SA-504, the flight vehicle for Apollo 9 was rolled out of the VAB on 3rd January 1969. The crew, James A. McDivitt, David R. Scott and Russell L. Schweickart were launched from ML-2 at Pad 39A on 3rd March 1969 to the Moon to practice rendezvous procedures between the Command Module “Gumdrop” and their Lunar Module “Spider”.

On 18th May 1969 Apollo 10 (SA-505) used two new facilities for their launch, ML-3 was finally christened by this launch and so was Launch Complex 39B (the only time this pad was used for a Moon launch). Eugene A. Cernan, John W. Young and Thomas P. Stafford successfully flight tested the Lunar Module “Snoopy” in the Moon’s gravitational field. They also tested the rendezvous ability once again with their Command Module “Charlie Brown”.

Apollo 10 inside the VAB - 30th December 1968

Apollo 10 at Pad B - 13th May 1969

Apollo 11 Rollout - 20th May 1969

Armstrong, Collins & Aldrin
The historic Apollo 11 rocket was rolled-out to Launch Complex 39A on top of ML-1 on 20th May 1969. On 16th July 1969 SA-506 was launched with her crew; Neil A. Armstrong, Edwin E. “Buzz” Aldrin, Jr. and Michael Collins. Neil Armstrong became the first man to set foot on another world on 20 July 1969 at 10:56:15 p.m. (EDT) when his and “Buzz” Aldrin’s Lunar Module “Eagle” landed at the “Sea of Tranquility” on the Moon. Michael Collins remained aboard their Command Module "Columbia" in orbit around the Moon.

Apollo 12 Rollout from VAB - 8th September 1969
The Apollo 12 (SA-507) crew, Charles Conrad, Jr., Richard F. Gordon, Jr. and Alan L. Bean, repeated the success of Apollo 11 on 14th November 1969 when they launched from LC-39A atop ML-2. Their “Yankee Clipper” Command Module and “Intrepid” Lunar Module went to the Moon and Conrad & Gordon made landfall in the “Ocean of Storm” on the surface of the Moon four days later.

Apollo 13 Rollout - 8th December 1969
The ‘successful failure’ of Apollo 13 re-ignited public interest in the space program. The Saturn-V (SA-508) launched from Pad 39A on ML-3 on 11th April 1970. James A. Lovell, Jr., John L. Swigert, Jr. and Fred W. Haise, Jr. were extremely lucky to survive an explosion in their Service Module on their way to the Moon.

Apollo 13 Damaged Service Module
They had to use their Lunar Module “Aquarius” as a life-boat as they made their way around the back of the moon before they could re-enter their Command Module “Odyssey”. Further problems developed with the Carbon-dioxide levels and energy consumption.

Throughout the mission, the public across the world waited with bated breath to see if the three men so far from home could possibly survive.

It was a minor miracle that the crew managed to re-start their frozen computers prior to re-entry and were able to control their trajectory to avoid burning up in the atmosphere.

The crew and many NASA personnel on Earth were put under extraordinary pressure and although the mission did not succeed in its primary mission - to land on the moon - the crew survived the experience thanks to a very dedicated and magnificent team.

Apollo 14 in the VAB - 1970
After the events of Apollo 13, the Apollo 14 mission was very carefully prepared indeed and eventually Alan B. Shepard, Jr. (America’s first Man in Space), Stuart A. Roosa and Edgar D. Mitchell flew SA-509 to the Moon, launched from ML-2 at LC-39A on 31st January 1971. Shepard and Roosa landed “Antares” at Apollo 13’s destination; “Fra Mauru” while Mitchell orbited in the “Kitty Hawk”.

Apollo 15 Rollout - 11th May 1971

Apollo 15 (SA-510) flew successfully from ML-3 at Pad 39A again on 26th July 1971 taking David R. Scott and James B. Irwin to “Hadley-Apennine” on the Moon aboard “Falcon” while Alfred M. Worden flew “Endeavour”.

Apollo 16 Rollout - 31st December 1971

ML-3 also launched Apollo 16 (SA-511) from LC-39A successfully nearly a full year later on 16th April 1972. John W. Young and Charles M. Duke, Jr. landed the LM “Casper” in the “Descartes Highlands” on the surface of the Moon while Thomas K. Mattingly II took care of their Command Module "Orion".

Apollo 17 Rollout - 28th August 1972

Apollo 17 Night Launch - 7th December 1972

The final manned mission to the Moon, Apollo 17 (SA-512) was also launched by ML-3 from LC-39A on 7th December 1972. Eugene A. Cernan & Harrison H. Schmitt descended to the “Taurus-Littrow Highlands” aboard “Challenger” along with a Lunar Roving Vehicle. Ronald E. Evans was the Command Module “America” pilot.

Skylab 1 Launches from Pad A while Skylab 2 is prepared on Pad B - 14th May 1973
The next use of the Mobile Launchers was for the SkyLab project. The Space Station itself was launched atop a modified Saturn-V rocket from LC-39A on the modified ML-2. The Crew Service Arm had been moved lower down the tower for access to the laboratory section. The stack was launched on 14th May 1973. The launch was fairly successful, but the first crew up to the station had to endure a long spacewalk in order to repair damage which occurred during the launch.

Skylab 2 Rollout - 26th February 1973
At the same time the unmanned SkyLab-1 Saturn-V launch vehicle was being prepared on LC-39A, over at LC-39B a heavily modified ML-1 was being prepared to launch a much smaller Saturn-1B rocket for the manned SkyLab-2 mission. The Mobile Launcher had been modified with a tall pedestal or ‘Milkstool’ to raise the rocket up to use the existing Service Arms for the Saturn-V. In essence, the top stages of both rockets were fundamentally the same, so this was a logical way of using the existing hardware. The three crewmen; Charles Conrad, Jr., Paul J. Weitz and Joseph P. Kerwin were launched on 25th May 1973, and performed repairs to the station before successfully continuing their 28 day mission.

Skylab 3 Launch - 28th July 1973
SkyLab-3, another Saturn-1B, launched from ML-1 at LC-39B, followed on 28th July 1973 taking Alan L. Bean, Jack R. Lousma and Owen K. Garriott up to the laboratory for their 59 day mission.

Skylab 3 Launch - 16th November 1973

Skylab 4 Launch - 16th November 1973
SkyLab-4 launched on 16th November 1973 taking Gerald P. Carr, William R. Pogue and Edward G. Gibson up to the Station for their 84 day mission aboard a third Saturn-1B rocket. As before, this mission launched from ML-1 at Pad 39B. This was the last visit to SkyLab. Eventually it impacted the surface of the Earth on 11th July 1979. According to NASA, the debris rained down across the South-Eastern Indian Ocean and across a sparsely populated section of Western Australia.

Apollo/Soyuz Test Program975
The final use of an Apollo-era Mobile Launcher was on 15th July 1975 for the Apollo/Soyuz Test Program. Another Saturn-1B was used atop the Milkstool on ML-1. The 9 day mission undertaken by Thomas P. Stafford, Vance D. Brand and Donald K. Slayton was to rendezvous and dock with a Russian Soyuz module in orbit. The docked segment of the mission lasted two days and both craft returned safely to the Earth.

After Apollo:

Dismantling ML-2 - 2nd March 1976
Once NASA’s new reusable Space Shuttle concept was confirmed, the launch facilities at LC-39 had to be extensively modified to work with the new design.

The Apollo-era Mobile Launchers would become a very significant part of the new Launch system.

Mobile Launch Platform - 24th September 1976

All three ML’s were carefully dismantled with plans for their re-use. The 380ft tall red LUT towers were separated from all three of the 2-story grey Launcher Bases. The Bases were later converted for use with the Shuttle, and today they are designated as Mobile Launcher Platforms (MLP). The Shuttle Stacks (consisting of 2 Solid-Rocket Boosters, External Fuel Tank and Orbiter) are mounted upon the MLP’s in the modified Vehicle Assembly Building (VAB). They are then rolled out to the same Launch Pads that were used during the Apollo-era, and are launched directly off of the MLP, just like the Saturn-V’s before them.

Moving ML-3 to Pad B - 20th July 1976
The red LUT towers of ML-2 and ML-3 were also re-used for Shuttle operations. Most of the structure of ML-2 is today fixed in position on the concrete Launch Pad at LC-39A forming the backbone of the Fixed Service Structure (FSS). Attached to the FSS is an all-new structure, called the Rotating Service Structure (RSS). This assembly rotates around the Shuttle’s cargo-bay to provide a clean-room environment out at the Pad, for preparing each mission payload before flight.

STS-1 Columbia Rollout - 29th December 1980

Service Arms in the Boneyard at John F. Kennedy Space Center
The red LUT tower of ML-1, along with the grey Milkstool, were decommissioned and carefully dismantled. NASA had planned on scrapping the tower, but a public campaign resulted in the tower being dismantled in such a way that it could be re-built relatively easily at a later date. It was put into outdoor storage behind the HQ building at the John F. Kennedy Space Center (KSC) in a “boneyard”, where it still rests today.

Segments of ML-1 Tower in the Boneyard at John F. Kennedy Space Center
This tower launched most of the really significant missions in the Apollo program (First Saturn-V launch, First Men to Orbit the Moon, First Men to Land on the Moon, all 3 Skylab manned missions & the Apollo-Soyuz Test Program). Other than the Apollo Capsules recovered after their flights, this is the only original piece of equipment used to launch Men to the Moon that still exists today.

Most of the tower still resides in the same boneyard as you read this, slowly gathering rust. Two segments, and LUT-1’s Hammerhead Crane, were reconditioned by the Smithsonian Institute and are on display, along with a potentially flyable Saturn-V rocket in the Apollo/Saturn-V Center at KSC.

It would be a desperate shame for this valuable piece of Mankind’s Heritage to disappear forever, so if you think you can assist or wish to show your support for saving ML-1, I would ask you to contact Doug Forrest and David Erbas-White who are managing this worthy campaign: www.savethelut.org.

Mission: Vehicle: Rollout: Launch: ML: Pad: Crew:

Static Test AS-500F 25th May 1966 Never flown 1 39-A Never flown
Apollo 4 AS-501 19th June 1967 9th November 1967 1 39-A Unmanned
Apollo 6 AS-502 6th February 1968 4th April 1968 2 39-A Unmanned
Apollo 8 AS-503 14th August 1968 21st December 1968 1 39-A Frank Borman, James A. Lovell, Jr., William A. Anders
Apollo 9 AS-504 3rd January 1969 3rd March 1969 2 39-A James A. McDivitt, David R. Scott, Russell L. Schweickart
Apollo 10 AS-505 11th March 1969 18th May 1969 3 39-B Eugene A. Cernan, John W. Young, Thomas P. Stafford
Apollo 11 AS-506 20th May 1969 16th July 1969 1 39-A Neil A. Armstrong, Edwin E. "Buzz" Aldrin, Jr., Michael Collins
Apollo 12 AS-507 8th September 1969 14th November 1969 2 39-A Charles Conrad, Jr., Richard F. Gordon, Jr., Alan L. Bean
Apollo 13 AS-508 8th December 1969 11th April 1970 3 39-A James A. Lovell, Jr., John L. Swigert, Jr., Fred W. Haise, Jr.
Apollo 14 AS-509 9th November 1960 31st January 1971 2 39-A Alan B. Shepard, Jr., Stuart A. Roosa, Edgar D. Mitchell
Apollo 15 AS-510 11th May 1971 26th July 1971 3 39-A David R. Scott, James B. Irwin, Alfred M. Worden
Apollo 16 AS-511 13th December 1971 16th April 1972 3 39-A John W. Young, Thomas K. Mattingly II, Charles M. Duke, Jr.
Apollo 17 AS-512 28th August 1972 7th December 1972 3 39-A Eugene A. Cernan, Harrison H. Schmitt, Ronald E. Evans
SkyLab AS-513 16th April 1973 14th May 1973 2 39-A Unmanned
SkyLab 2 AS-206 26th February 1973 25th May 1973 1 39-B Charles Conrad, Jr., Paul J. Weitz, Joseph P. Kerwin
SkyLab 3 AS-207 11th June 1973 28th July 1973 1 39-B Alan L. Bean, Jack R. Lousma, Owen K. Garriott
SkyLab 4 AS-208 14th August 1973 16th November 1973 1 39-B Gerald P. Carr, William R. Pogue, Edward G. Gibson
Apollo/Soyuz AS-209 24th March 1975 15th July 1975 1 39-B Thomas P. Stafford, Vance D. Brand and Donald K. Slayton

All images, with the exception of the LUT in the 'boneyard',

belong to NASA and I am very grateful for permission to

reproduce them here.

The 'boneyard' pictures are reproduced here by kind

permission of Greg Katnik.