The Apollo/Skylab space suit (sometimes called the Apollo 11 Spacesuit for being used in the Apollo 11 Mission) is a class of space suits used in the Apollo and Skylab missions. In both missions, the space suit was referred to as the Extravehicular Mobility Unit (EMU). The Apollo EMU consisted of a Pressure Garment Assembly (PGA) and a Portable Life Support System (PLSS) that was more commonly called the "backpack".
The A7L was the PGA model used on the Apollo 7–14 lunar missions. The subsequent Apollo 15-17 missions, Skylab and Apollo–Soyuz used A7LB pressure suits. Additionally, these pressure suits varied by program usage. For the Skylab EMU, NASA elected to use an umbilical life support system named the Astronaut Life Support Assembly.
The suits used during lunar EVAs had a weight of about , and under lunar surface gravity a weight equivalent to . The low surface gravity and suit pressurization put considerable constraints on its use.
Basic design
The base Apollo EMU design took over three years to produce. At the beginning of the Apollo program, the Apollo spacesuit had not yet received its final EMU name. Between 1962 and 1964, the spacesuit was called the Space Suit Assembly (SSA). The Apollo SSA consisted of a Pressure Garment Assembly (PGA) and a backpack Portable Life Support System (PLSS).
NASA held a competition for the Apollo SSA contract in March 1962. Each competition proposal had to demonstrate all the abilities needed to develop and produce the entire SSA. Of the proposals submitted by various contractor teams, two gained NASA's interest:
The Hamilton Standard Division of United Aircraft Corporation proposed to provide SSA program management and the PLSS, with David Clark Company as the PGA provider. The International Latex Corporation (ILC) proposed to provide SSA program management and the PGA, with Republic Aviation providing additional suit experience and Westinghouse providing the PLSS.
After evaluation of the proposals, NASA preferred the Hamilton PLSS concept and program experience but the ILC PGA design. NASA elected to split the Hamilton and ILC teams, issuing the contract to Hamilton with the stipulation that ILC provide the PGA.
By March 1964, Hamilton and NASA had found three successive ILC Apollo PGA designs to not meet requirements. In comparative testing, only the David Clark Gemini suit was acceptable for Apollo Command Module use. While the Hamilton PLSS met all requirements, crewed testing proved the life support requirements were inadequate, forcing the Apollo SSA program to start over.
In October 1964, NASA elected to split the spacesuit program into three parts. David Clark would provide the suits for the "Block I" early missions without extra-vehicular activity (EVA). The Hamilton/ILC program would continue as "Block II" to support the early EVA missions. The pressure suit design for Block II was to be selected in a June 1965 re-competition. To assure Block II backpack success, Garrett AiResearch was funded for a parallel backpack effort. The later, longer-duration Apollo missions would be designated as Block III and have more advanced pressure suits and a longer duration backpack to be provided by suppliers selected in future competitions.
Hamilton and International Latex were never able to form an effective working relationship. In March 1965, Hamilton switched to B. F. Goodrich as suit supplier. ILC, in July 1965, won the Block II suit competition with its A5L design. This forced NASA to assume management of the Block II EMU program directly. Before the end of 1965, Hamilton Standard completed certification of its new backpack. NASA subsequently terminated the Block II AiResearch backpack, thus completing the selection of the suit/backpack designs and suppliers to support man's first walking on the Moon. However, this was not to be without improvements. The Apollo 11 EMU featured an A7L suit with a -6 (dash six) backpack reflecting seven suit and six backpack design iterations. The A7L was a rear entry suit made in two versions. The Extra-vehicular (EV), which would be used on the Moon and the Command Module Pilot (CMP) that was a simpler garment.
The ILC Dover team, however, collaborated quite well. Douglas N. Lantry, a scholar of the spacesuit manufacture in the Apollo era, notes that the teamwork displayed by the ILC Dover seamstresses creating the spacesuits demonstrated the effectiveness of overlapping and cross-training on each others' specialties and expertise. This team of seamstresses, led by Hazel Fellows, included Iona Allen, Delema Austin, Doris Boisey, Julia Brown, Delema Comegys, Joanne Thompson, Michelle Trice, Jeanne Wilson, and Delores Zeroles.
The A7L pressure suits reached space flight in October 1968 aboard Apollo 7. These were used as launch and reentry emergency suits. Also in 1968, NASA recognized that with modifications, the Block II EMU could additionally support the later EVA missions that involved a Lunar Rover Vehicle (LRV). This resulted in the termination of Apollo Block III in favor of an Apollo 15 through 17 EMU using an A7LB suit and a "-7" long duration backpack.
The complete Apollo EMU made its space debut with Apollo 9 launched into space on March 3, 1969. On the fourth day of the mission, Lunar Module Pilot Russell Schweickart and Commander James McDivitt went into the Lunar Module. The astronauts then depressurized both the Command and Lunar Modules. Schweickart emerged from the Lunar Module to test the backpack and conduct experiments. David Scott partially emerged from the Command Module's hatch supported by an umbilical system connected to the Command Module to observe. The EVA lasted only 46 minutes but allowed a verification of both EVA configurations of the EMU. This was the only Apollo spacewalk prior to the Apollo 11 lunar landing mission.
Apollo 11 made the A7L the most iconic suit of the program. It proved to be the primary pressure suit worn by NASA astronauts for Project Apollo. Starting in 1969, the A7L suits were designed and produced by ILC Dover. The A7L is an evolution of ILC's initial A5L, which won a 1965 pressure suit competition, and A6L, which introduced the integrated thermal and micrometeoroid cover layer. After the deadly Apollo 1 fire, the suit was upgraded to be fire-resistant and designated A7L.
On July 20, 1969, the Apollo 11 EMUs were prominent in television coverage of the first lunar landing. Also in 1969, International Latex elected to spin off its pressure suit business to form ILC Dover.
The basic design of the A7L suit was a one piece, five-layer "torso-limb" suit with convoluted joints made of synthetic and natural rubber at the shoulders, elbows, wrist, hips, ankle, and knee joints. A shoulder "cable/conduit" assembly allowed the suit's shoulder to move forward, backwards, up, or down with user movements. Quick disconnects at the neck and forearms allowed for the connection of the pressure gloves and the famous Apollo "fishbowl helmet" (adopted by NASA as it allowed an unrestricted view, as well as eliminating the need for a visor seal required in the Mercury and Gemini and Apollo Block I spacesuit helmets). A cover layer, which was designed to be fireproof after the deadly Apollo 1 fire, was attached to the PGA and was removable for repairs and inspection. All A7L suits featured a vertical zipper from the helmet disconnect (neck ring), down the back, and around the crotch.
Specifications, Apollo 7–14 EMU Name: Extravehicular Mobility Unit (EMU) Manufacturers: ILC (Pressure Garment Assembly) and Hamilton Standard (Portable Life Support System) Missions: Apollo 7–14 Function: Intra-vehicular activity (IVA), orbital Extra-vehicular activity (EVA), and terrestrial EVA Operating Pressure: 3.7 psi (25.5 kPa) IVA Suit Mass: 62 lb (28.1 kg) EVA Suit Mass: 76 lb (34.5 kg) Total EVA Suit Mass: 200 lb (91 kg) Primary Life Support: 6 hours Backup Life Support: 30 minutes
Extravehicular Pressure Garment Assembly
Torso Limb Suit Assembly Between Apollo 7 and Apollo 14, the Commander (CDR) and Lunar Module Pilot (LMP), had Torso Limb Suit Assemblies (TSLA) with six life support connections placed in two parallel columns on the chest. The 4 lower connectors passed oxygen, an electrical headset/biomed connector was on the upper right, and a bidirectional cooling water connector was on the upper left.
Integrated Thermal Micrometeoroid Garment Covering the Torso Limb Suit Assembly was an Integrated Thermal Micrometeoroid Garment (ITMG). This garment protected the suit from abrasion and protected the astronaut from thermal solar radiation and micrometeoroids which could puncture the suit. The garment was made from thirteen layers of material which were (from inside to outside): rubber coated nylon, 5 layers of aluminized Mylar, 4 layers of nonwoven Dacron, 2 layers of aluminized Kapton film/Beta marquisette laminate, and Teflon coated Beta filament cloth.
Additionally, the ITMG also used a patch of 'Chromel-R' woven nickel-chrome (the familiar silver-colored patch seen especially on the suits worn by the Apollo 11 crew) for abrasion protection from the Portable Life Support System (PLSS) backpack. Chromel-R was also used on the uppers of the lunar boots and on the EVA gloves. Finally, patches of Teflon were used for additional abrasion protection on the knees, waist and shoulders of the ITMG.
Starting with Apollo 13, a red band of Beta cloth was added to the commander's ITMG on each arm and leg, as well as a red stripe on the newly added EVA central visor assembly. The stripes, initially known as "Public Affairs stripes" but quickly renamed "commander's stripes", made it easy to distinguish the two astronauts on the lunar surface and were added by Brian Duff, head of Public Affairs at the Manned Spacecraft Center, to resolve the problem for the media as well as NASA of identifying astronauts in photographs.
Liquid Cooling Garment Lunar crews also wore a three-layer Liquid Cooling and Ventilation Garment (LCG) or "union suit" with plastic tubing which circulated water to cool the astronaut down, minimizing sweating and fogging of the suit helmet. Water was supplied to the LCG from the PLSS backpack, where the circulating water was cooled to a constant comfortable temperature by a sublimator.
Portable Life Support System At the beginning of the Apollo spacesuit competition, no one knew how the life support would attach to the suit, how the controls needed to be arranged, or what amount of life support was needed. What was known was that in ten months, the Portable Life Support System, aka "backpack", needed to be completed to support complete suit-system testing before the end of the twelfth month. Before the spacesuit contract was awarded, the requirement for normal life support per hour almost doubled. At this point, a maximum hourly metabolic energy expenditure requirement was added, which was over three times the original requirement.
In late 1962, testing of an early training suit raised concerns about life support requirements. The concerns were dismissed because the forthcoming Apollo new-designs were expected to have lower effort mobility and improved ventilation systems. However, Hamilton took this as a strong indication that Apollo spacesuit life support requirements might significantly increase and initiated internally funded research and development in "backpack" technologies.