A spacesuit is a pressurized garment worn by astronauts during space flights. It is designed to protect them from the potentially damaging conditions experienced in space. Spacesuits are also known as Extravehicular Mobility Units (EMUs) to reflect the fact that they are also used as mobility aides when an astronaut takes a space walk outside of an orbiting spacecraft. They are composed of numerous tailor-made components that are produced by a variety of manufacturers and assembled by the National Aeronautics Space Agency (NASA) at their headquarters in Houston. The first spacesuits were introduced during the 1950s when space exploration began. They have evolved overtime becoming more functional and complicated. Today, NASA has 17 completed EMUs, each of which cost over $10.4 million to make.
On Earth, our atmosphere provides us with the environmental conditions we need to survive. We take for granted the things it provides such as air for breathing, protection from solar radiation, temperature regulation and consistent pressure. In space, none of these protective characteristics are present. For example, an environment without consistent pressure doesn't contain breathable oxygen. Also, the temperature in space is as cold as -459.4° F (-273° C). For humans to survive in space, these protective conditions had to be synthesized.
A spacesuit is designed to re-create the environmental conditions of Earth's atmosphere. It provides the basic necessities for life support such as oxygen, temperature control, pressurized enclosure, carbon dioxide removal, and protection from sunlight, solar radiation and tiny micrometeoroids. It is a life-support system for astronauts working outside Earth's atmosphere. Spacesuits have been used for many important tasks in space. These include aiding in payload deployment, retrieval and servicing of orbiting equipment, external inspection and repair of the orbiter, and taking stunning photographs.
Spacesuits have evolved naturally as technological improvements have been made in areas of materials, electronics and fibers. During the early years of the space program, spacesuits were tailor made for each astronaut. These were much less complex than today's suits. In fact, the suit worn by Alan Shepard on the first U.S. suborbital was little more than a pressure suit adapted from the U.S. Navy high-altitude jet aircraft pressure suit. This suit had only two layers and it was difficult for the pilot to move his arms or legs.
The next generation spacesuit was designed to protect against depressurization while the astronauts were in an orbiting spacecraft. However, space walks in these suits were not possible because they did not protect against the harsh environment of space. These suits were made up of five layers. The layer closest to the body was a white cotton underwear that had attachments for biomedical devices. A blue nylon layer that provided comfort was next. On top of the blue nylon layer was a pressurized, black, neoprene-coated nylon layer. This provided oxygen in the event that cabin pressure failed. A Teflon layer was next to hold the suit's shape when pressurized, and the final layer was a white nylon material that reflected sunlight and guarded against accidental damage.