Apollo/Skylab A7L

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The A7L Apollo & Skylab spacesuit is the primary pressure suit worn by NASA astronauts for Project Apollo, the three manned Skylab flights, and the Apollo-Soyuz Test Project between 1968 and the termination of the Apollo program in 1975. The "A7L" designation is used by NASA as the seventh Apollo spacesuit designed and built by ILC Dover, a pressure suit manufacturer located south of Dover, Delaware.

[edit] Basic Design

The basic design of the A7L suit was a one piece, five-layer "torso-limb" suit with convoluted joints made of synthetic rubber at the elbow and knee joints, "link-net" meshing to prevent the suit from ballooning, and a shoulder "cable block" assembly to allow the shoulder to be extended and retracted by its wearer. Metal rings 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 program and Gemini program spacesuit helmets). A "cover layer," which was designed to be fireproof after the Apollo 1 launchpad fire, was attached to the pressure suit assembly with Velcro, and was removable for repairs.

Between Apollos 7 and 14, the two astronauts who would perform the moonwalks, the Commander (CDR) and Lunar Module pilot (LMP), had suits with six life support connections, placed in two parallel rows at the chest and waist, while the Command Module pilot (CMP) had a suit with only three – as he would remain in the spacecraft during the entire mission, and his suit had to only protect him if the spacecraft would either depressurize or catch on fire (similar in nature to Apollo 1, but on a somewhat lesser scale due to a change in atmospheric makeup and pressure on the launchpad – 60% oxygen and 40% nitrogen at 14.7 psi). Another difference, besides the number of connectors, were the number of layers. Lunar crews wore suits with a total of 21 layers, including the five-layer pressure suit assembly, and a three-layer specialized "union suit" with plastic tubing which circulated cooling water to cool the astronaut down, minimizing sweating and fogging of the suit helmet (see: Liquid Cooling and Ventilation Garment). Command module pilots wore a three-layer cover layer for fire protection and a simpler union suit without the plastic tubing; his cooling coming directly from the flow of oxygen in his suit.

All A7L suits featured a vertical zipper that went from the shoulder assembly of the suit down to the crotch. It too was covered by a flap, with the suits for the commander and lunar module pilots featuring a patch of "Chromel-R" woven steel (the familiar silver-colored patch seen especially on the suits worn by the Apollo 11 crew) for abrasion protection from the life support backpack. Chromel-R is also used on the uppers of the lunar boots and on the EVA gloves.

[edit] A7L-B Spacesuit (Apollo & Skylab)

For the last three Apollo lunar flights Apollos 15, 16, and 17, the CDR and LMP started wearing a new moonwalking suit designed for longer duration J-series missions, in which three EVAs would be conducted and the lunar rover (LRV) would be used for the first time. Originally developed by ILC-Dover as the "A8L," but given the designation "A7L-B" by NASA, the new suit incorporated improved shoulder, elbow, and knee joints, along with an improved waist joint that allowed the astronaut to bend over and even sit on the LRV. Because of the waist joint, the six life-support connecters were rearragned from the parallel pattern to a set of two "triangles," and the up-and-down zipper was relocated to the left front side of the suit, going around the back, and terminating on the right shoulder.

In addition, the EVA backpacks were modified to carry more oxygen, lithium hydroxide (LiOH), and cooling water for the longer EVAs and a red band was incorporated on each arm and leg, as well as on the EVA helmet cover to easily distinguish the commander from the LMP (in actuality, it was first introduced on Apollo 13, but because of the oxygen tank malfunction, the bands "saw action" on Apollo 14).

Because the J-series CSMs incorporated the Scientific Instrument Module (SIM) Bay, which used special film cameras similar to those used on Air Force spy satellites, and required a "deep space" EVA for retrieval, the CMP for each of the three J-series missions wore a five-connector version of the early H-series A7L suits, with the liquid cooling connections eliminated as the CMP would be attached to a life-support umbilical (like that used on Gemini EVAs) and only an "oxygen purge system" (OPS) would be used, along with a "red apple" lanyard, for emergency backup in the case of the failure of the umbilical. The CMP wore the commander's red-striped EVA visor assembly, while the LMP, who performed a "stand-up EVA" (to prevent the umbilical from getting "fouled up" and to store the film into the CSM) in the spacecraft hatch and connected to his normal life-support connections, wore the plain white EVA assembly.

For the three manned Skylab missions, all three astronauts wore a slightly modified A7L-B suit for launch, docking and undocking phases, and EVA (reentry and landing were done wear in-flight coveralls, as a precursor to the "shirt-sleeve" environment used on the Space Shuttle flights from STS-5 to STS-51-L), the last item being carried out by all three astronauts, depending upon the requirements set forth by Mission Control in Houston.

With the exception of the Orbital Workshop (OWS) repairs carried out by Skylab 2, all of the Skylab EVAs were conducted in connection to the routine maintenance carried out on the Apollo Telescope Mount, which housed the station's solar telescopes. Because of the short duration of those EVAs, and as a need to protect the delicate instruments, the Apollo lunar EVA backpack was replaced with a Gemini-style umbilical assembly, except that it was modified to incorporated both breathing air (Skylab's atmosphere was 80% oxygen and 20% nitrogen at 5 psi) and liquid water for cooling. The assembly was worn on the astronauts waist and served as the interface between the umbilical and the suit. An emergency oxygen pack was strapped to the wearer's right thigh and is able to supply a 30 minute emergency supply of pure oxygen in the case of umbilical failure. An EVA visor assembly similar to that used today on the Shuttle/ISS Extravehicular Mobility Unit was worn over the pressure helmet, but Apollo EVA gloves were used.

[edit] A7L-B Suit (Apollo-Soyuz Test Project)

For the Apollo-Soyuz Test Project, NASA decided to revert back to the A7L CMP pressure suit assembly worn on the H-missions, with its three connectors, but now incorporating a new outer cover layer similar to that used on the Skylab A7L-B suits. Despite its pedigree, NASA gave the suits an "A7L-B" designation and they functioned perfectly, the only mistake being that the astronauts removed their pressure helmets and because of a malfunction on the spacecraft's reentry RCS systems, allowed poisonous hypergolic gases to enter the crew cabin, injuring all three astronauts and nearly killing one; his life being saved when mission commander Brigadier General Thomas Stafford strapped an oxygen mask to his face immediately after splashdown.

As a note, the ASTP A7L-B suit were the only Apollo suit to use the "worm" logo, a logo that became familiar with all of NASA's pressure, space, and flight suits and all Space Shuttle orbiters between 1981 and 2000.