A different job from earlier suits
The suits worn in Earth orbit during the early 1960s were mainly protective garments that stayed inside a cabin. Walking on the Moon asked for something else: a self-contained, wearable spacecraft. The wearer needed to bend, kneel, pick up rocks and carry tools, in a vacuum, in strong sunlight and deep shadow, for several hours at a time and with no cabin to retreat to.
Because the title speaks of “the first” space suit, it is worth saying that no single suit deserves that label. The Moon suits were one stage in a long development, described in other articles on the earlier pressure suits and the Mercury suit. This article covers the suits built for the Apollo lunar landings between 1969 and 1972.
The suit itself
The Apollo suit, commonly known by the designation A7L, was a multilayer garment. In broad terms, it had these parts:
- An inner liner and a pressure layer. A gas-tight bladder held the air pressure around the body. Cloth restraint layers kept the bladder from ballooning.
- A liquid-cooled garment. Worn underneath, it was a close-fitting suit threaded with thin tubes of water.
- Insulation and protective outer layers. Multiple thin layers reduced heat transfer and protected against tears and tiny meteoroid impacts. These layers included fabrics made from synthetic fibers, including a glass-based cloth that resisted fire.
- Joints. Convoluted sections at shoulders, elbows, knees and hips let the wearer bend despite the internal pressure.
The suit was not inflated to sea-level pressure. Instead it held a lower pressure of pure oxygen, which kept the suit flexible enough to move in. The pressure level is usually given as a little under 4 psi; sources round it slightly differently.
The backpack and its life support
The backpack was called the Portable Life Support System. It did the work of an atmosphere, an air conditioner and a radio all at once.
- It supplied oxygen and removed carbon dioxide from the suit.
- It circulated cool water through the tubes of the liquid-cooled garment.
- It carried the radio equipment for contact with the lunar module and Mission Control.
Cooling is the part that surprises many readers. On the Moon a suited astronaut produces heat, and in a vacuum there is no air to carry it away. The cooling water carried heat from the body to the backpack, where it was dissipated by letting water turn to vapor in a device that vented to space. In effect the backpack lost heat by sacrificing a small amount of water. The same idea shows up in other thermal systems, though the exact engineering differs.
The backpack was sized for outings of several hours on the early missions, with a reserve supply for emergencies. Later missions extended the time outside, and the suits and backpacks were adjusted accordingly. Exact durations varied from mission to mission, so any single number should be treated as approximate.
The helmet, visor and boots
The helmet was a clear shell with an outer visor assembly. A thin metallic coating, often described as gold, reflected sunlight and infrared radiation. Lunar overboots went over the inner suit boots to protect against rock and abrasive dust. Gloves were one of the hardest parts: they had to hold pressure and still allow fine hand movement, and astronauts often reported tired hands after long periods of work.
Lessons from the fire and from the surface
The Apollo 1 fire in January 1967 killed three astronauts during a ground test and led to major changes in the program. Materials in the spacecraft and the suits were reviewed, and fire-resistant fabrics were adopted for the Apollo-era garments. The crew in that test were wearing early versions of the suits, and the accident is part of the reason the later suits look the way they do.
The later missions, from Apollo 15 on, used an upgraded suit design, usually listed as the A7LB, with more flexible waist and hip joints. These helped crews bend and sit in the lunar rover. Dust was a recurring complaint: fine lunar particles clung to fabrics and joints and wore on them over repeated outings.
Why these suits mattered
The lunar suits showed that a person could work for hours outside a spacecraft with an independent supply of air and cooling. The ideas of liquid cooling, layered insulation and portable life support carried through to later suits, including those used during repairs on Skylab and the stations that followed. Their descendants still show up wherever people work outside in space, and the same general approach is used today even though the materials and details have changed.