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Spacesuit

Each complete spacesuit costs over $12 million to make.

A spacesuit is a pressurized (filled with air pressure) garment worn by astronauts during space flights. It is designed to protect them from potential dangerous conditions they may experience in space. A spacesuit is also called an Extravehicular Mobility Unit (EMU) because it is worn when an astronaut leaves the spacecraft in order to perform a variety of tasks, including the repair of satellites, collection of samples, taking of pictures, and assembling of equipment.

The spacesuit is designed to recreate 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 micrometeoroids.

The white spacesuit weighs about 275 pounds (124.8 kilograms) on Earth. However, above Earth's atmosphere, or in space, it has no weight at all due to the near absence of gravity. Contrary to popular belief, it is not true that there is absolutely no gravity in space. What is commonly referred to as zero gravity in space is more accurately called microgravity, or very little gravity. Just the same, spacesuits are weightless in space.

The spacesuit is reusable and has a product life expectancy of about fifteen years. The suit is pressurized to 4.3 pounds per square inch (0.302 kilogram per square centimeter) and can be recharged by hooking up to the orbiter (piloted part of a spacecraft). Unlike previous spacesuits, which were tailor-made for each astronaut, today's spacesuits can be assembled from standard-sized parts to fit any body size. The basic interchangeable sections include the helmet, the hard upper torso, the arms, and the lower torso. These parts are adjustable and can be resized. Each complete spacesuit has fourteen layers and costs over $12 million to make.

Early spacesuits

The space age began in 1957 when the former Soviet Union launched Sputnik, an unmanned, artificial (manmade) satellite, into space. In 1958, the United States created the National Aeronautics and Space Administration (NASA) to develop space exploration. The first spacesuits were introduced around this time and have since undergone changes that resulted in a more functional, although more complicated, design.

Astronauts of the Mercury program, the first U.S.-manned space program, in the early 1960s wore a pressure suit patterned after those worn by U.S. Navy high-altitude jet aircraft pilots. On May 5, 1961, Alan B. Shepard Jr. (1923–1998), America's first man in space, wore such a suit, made of only two layers of nylon fabric with fabric breaks in the elbow and knee areas for movement.

The Mercury astronauts wore the spacesuits unpressurized, or uninflated. They could pressurize the suits in the event that the spacecraft cabin lost pressure, which never occurred in any of their six missions.

Next, designers developed a five-layer spacesuit. Like the first spacesuits, it could be pressurized when necessary. The layer closest to the body was a white cotton undergarment with attachments for biomedical devices, such as a heart-rate monitor. A blue nylon layer that provided comfort was next. The third layer consisted of a black, pressurized, neoprene-coated nylon that provided oxygen in the absence of cabin pressure. A Teflon® layer served to hold the suit's shape when pressurized. The final layer was a white nylon material that reflected sunlight and guarded against accidental damage.

Spacesuit for the Gemini spacewalkers

Of the twelve Gemini missions between 1964 and 1966, ten were manned launches. For these first spacewalks ever undertaken by astronauts, a seven-layer suit was designed. The extra layers were made up of aluminized Mylar®, which provided protection against extreme heat and micrometeoroids. Micrometeoroids are very tiny particles of matter left over from the formation of the solar system and from the collisions of comets and asteroids. These particles travel at very high speeds and are capable of penetrating human skin. The spacesuit weighed 33 pounds (15 kilograms).

Suiting for moon walks

The Apollo Program, conducted between 1961 and 1972, was designed to land an astronaut on the moon and bring the person back to Earth. On July 20, 1969, Neil A. Armstrong (1930–) and Edwin E. "Buzz" Aldrin Jr. (1930–) became the first two persons to walk on the moon. Ten other Apollo astronauts walked on the moon after that.

For moon walks, the astronauts wore a seven-layer spacesuit with a life-support backpack. The total weight was about 57 pounds (26 kilograms). As with the Mercury and Gemini suits, the Apollo garment had to function as a pressure suit in the event of cabin pressure loss. The spacesuit was constructed so that it not only allowed movement of the shoulders and arms but also of the legs. The astronauts had to be able to bend and stoop down so that they could collect samples on the moon to take back to Earth. The design of the suit also had to take into consideration the extreme heat of the lunar day and the micrometeoroids that slammed against the lunar surface.

Raw Materials

A spacesuit is made from numerous raw materials. Fabric materials include a variety of synthetic polyester. The innermost layer is made of nylon tricot. The second layer is made of spandex, a synthetic stretch fabric. The pressure garment is made of urethane-coated nylon. On top of this is Dacron®, a type of polyester that acts as a restraint and keeps the pressure garment from ballooning. Other synthetic fabrics include neoprene, aluminized Mylar®, Gortex®, Kevlar®, and Nomex®. Many of these synthetic fabrics have been known for their outstanding properties. For example, Kevlar® has been used for making bulletproof vests for the police for more than two decades, and Nomex®, with its heat- and flame-resistant properties, is the fabric used by firefighters and race car drivers.

Aside from the fabric materials, other raw materials play important roles. Fiberglass (made from compressed glass fibers) is the primary material for the hard upper torso. Lithium hydroxide and activated charcoal make up the filter that removes carbon dioxide and water vapor during a spacewalk. A silver zinc blend makes up the battery that powers the suit. Plastic tubing is woven into the fabric to transport cooling water throughout the suit. A polycarbonate (plastic) material is used to build the helmet shell. Different components are used to make up the electric circuitry and suit controls.

Design

A spacesuit or Extravehicular Mobility Unit (EMU) is constructed from various tailor-made components manufactured by more than eighty companies. EMUs come in standard-sized parts that are assembled by NASA.

The primary-life support system is a self-contained backpack with an oxygen supply, carbondioxide removal filters, caution and warning system, electrical power, water-cooling equipment, ventilating fan, machinery, and radio. The suit tank contains enough oxygen to last for seven hours. A secondary oxygen pack in the spacesuit provides emergency oxygen to last another thirty minutes.

The helmet is a large, plastic, pressure bubble with a neck-disconnect ring and a ventilation-distribution pad. It has a backup purge valve, which is used with the secondary oxygen pack to remove exhaled carbon dioxide. Also in the helmet is a tube that extends from a drink bag in the hard upper torso. The tube acts like a straw for drinking the water in the drink bag.

The helmet has an extravehicular visor assembly (EVA) with a sun-filtering visor, a clear impact-protective visor, and adjustable blinders. A light-bar attachment sits on top of the EVA. It consists of small flood lamps that light up areas not reached by sunlight or other sources of light. Also mounted on the EVA is a television camera system through which the crew inside the orbiter and mission controllers on Earth can see what the astronaut sees in space. It also enables those personnel to offer advice when needed.

The communications carrier assembly (CCA), also called a "Snoopy cap," is a fabric cap fitted with earphones and a microphone. It is attached to the spacesuit electrical harness and worn on the head.

A liquid cooling and ventilation garment comes next. It looks like a pair of longjohns with a zippered front and is made of stretchable spandex. It is fitted with about 300 feet (91.5 meters) of plastic cooling tubes through which chilled water is circulated. Since spacesuits trap heat, the circulating water keeps the astronaut cool. The astronaut can stop the circulation if he or she gets too cold.

The lower torso, which is put on before the hard upper torso, is made up of the pants, a maximum absorption garment (adult-size diaper), boots, the lower half of the waist closure, and knee and ankle joints. The pants consist of a pressure garment bladder (an inflatable garment) made of urethane-coated nylon, followed by a Dacron® restraint layer to keep the bladder from ballooning. Seven layers of aluminized Mylar® materials provide insulation, followed by the outer layer made of fabric blends of Gortex®, Kevlar®, and Nomex® materials. The lower torso can be made shorter or longer by adjusting the sizing rings in the thigh and leg section. The boots have an insulated toe cap to improve heat retention. Thermal socks are also worn.

The arm assembly is adjustable just like the lower torso. It has a glove-attaching closure. The gloves contain miniature battery-powered heaters in each finger. The rest of the unit is covered by padding and an additional protective outer layer. The gloves have loops for attaching tethers (a ropelike restraint) for holding small tools and equipment.

An important component of the upper half of the suit is the hard upper torso, which is made of a fiberglass shell under fabric layers of the thermal micrometeoroid garment. It resembles the breast and back plates of a suit of armor. The hard upper torso is a mounting structure for different components, including the helmet, arms, lower torso, the upper half of the waste closure, the electrical harness, and the drink bag. In addition, the primary life-support system attaches at the back, while the display and control module that runs it attaches on the front.

The chest-mounted display and control module contains a digital display panel and all electrical and mechanical operating controls. It enables the astronaut to connect to external sources of fluids and electricity. The module is connected to the warning system in the upper torso to let the astronaut know the status of the suit's environment. A purge valve in the module can be opened, allowing contaminated gases and water vapor to flow out of the valve into space.

When the upper torso is not in use, it is connected to the orbiter airlock (airtight chamber) support system through a service and cooling umbilical line. Connections within the umbilical line allow the orbiter to provide the spacesuit with electrical power, cooling water, and oxygen, so that the contents of the primary life-support system are conserved. The umbilical line is also used for battery recharging. A silver zinc rechargeable battery, operating at seventeen volts, powers the suit.

The Manufacturing Process

The manufacture of a modern spacesuit consists of two phases. First, the individual components are constructed. Then, the finished components are brought to a primary manufacture location, such as the NASA headquarters in Houston, Texas, and put together.

Helmet and visor assembly

1 The helmet and visor are constructed using injection molding. Pellets of polycarbonate, or plastic, are melted and then forced under high pressure into a mold with the shape of the helmet/visor. As it cools, the plastic assumes the shape of the mold. A connecting device is added to the open end of the helmet so that it can be attached to the hard upper torso. The ventilation distribution pad and the purge valves are added before the helmet is packaged and shipped. The visor assembly is fitted with a "head lamp" and communications equipment.

Primary life-support systems

2 The primary life-support system has several components, which are put together one at a time. Then all the pieces are put into the backpack unit. First, the pressurized oxygen tanks are filled, capped, and put into the backpack. The carbon-dioxide removal equipment is assembled. This consists of a filter canister filled with lithium hydroxide and activated charcoal, which is attached to a hose. The backpack is then fitted with a ventilating fan system, a radio, a warning system, and the water-cooling equipment. When completed, the life-support system is attached to the hard upper torso.

Display and control module

3 The key components of the display and control module are built as separate units and then assembled. This allows the parts to be easily serviced if necessary. The module contains all the electronic and mechanical operating controls, a digital display, and other electronic interfaces. The purge valve is also added to the module.

Liquid cooling and ventilation garment

4 The liquid cooling and ventilation garment makes up the first two layers of the spacesuit that are worn next the skin. Nylon tricot is first cut into a garment that resembles a pair of longjohns. Meanwhile, the spandex fibers are woven into a sheet of fabric and cut into the same shape. The spandex is fitted with a series of plastic cooling tubes 300 feet (91.5 meters) long and sewn to the nylon material. A front zipper is attached, as well as connectors for attachments to the life-support system.

Upper and lower torso

5 The various layers of synthetic fibers for the pants, arm assembly, and gloves are woven together and then cut into the appropriate shapes. The segments are then attached. Waist closures are added for attaching to the upper torso. The arm assembly is fitted with glove-attaching closures. The gloves are fitted with miniature heaters in every finger, then covered with padding and a protective outer layer.

6 The hard upper torso is made from fiberglass and metal. It has four openings where the lower torso, arms, and helmet attach. Adapters are added on the front and back for attachment of the primary life-support system and the display and control module.

Final assembly

7 The finished components are shipped to NASA for assembly. This is done on the ground so that the spacesuit can be tested before being used in space.

Quality Control

The individual suppliers conduct quality tests at each step of the manufacturing process. The manufacturers make sure they satisfy NASA standards, ensuring that the suits will function in the extreme environment of space. They check for such things as air leakage, depressurization, and defective life-support systems. The testings are very important because even a single malfunction could have serious adverse results for an astronaut in space.

The Future

The EMU design used today is a product of many years of research and development. However, research continues to perfect this design. One area that can be improved is a suit that would provide more pressure so that the "prebreathing" time can be reduced. (See sidebar.) Resizing of the suit in orbit also needs more research. Currently, it takes a significant amount of time to remove or add extending inserts in the leg and arm areas. The electronic controls of the suit also need improvement. Researchers are working on replacing the complex command codes with buttons that just have to be pressed.

airlock:

An airtight chamber between two places with differing air pressure, such as between the inside and the outside of a space capsule, and in which the air pressure can be changed to match that of either place.

astronaut:

A person trained to pilot a spacecraft and/or perform scientific experiments in space.

biomedical:

Having to do with the study of the human body's ability to survive under environmental stresses and conditions, such as while traveling in space.

capsule:

A pressurized vehicle that transports astronauts on space flights.

micrometeoroids:

Very tiny particles of matter left over from the formation of the solar system and from the collisions of comets and asteroids that travel at very high speeds in space and are capable of penetrating human skin.

neoprene:

A synthetic, or artificial, rubber that is resistant to heat, light, and most solvents.

orbiter:

The piloted section of a spacecraft that travels through space and lands like an airplane.

pressurize:

To maintain normal air pressure in the enclosed environment of a spacesuit or a spacecraft.

satellite:

A manmade object that orbits Earth, such as a communications satellite used to transmit television programs.

space shuttle:

A reusable spacecraft consisting of an orbiter, two solid rocket boosters, and an external fuel tank; used to carry out a variety of missions, including deploying satellites into space and conducting science experiments.

spacewalk:

A short trip by an astronaut outside the spacecraft to perform a task.

For More Information

Books

Dyson, Marianne J. Space Station Science: Life in Free Fall. New York, NY: Scholastic, Inc., 1999.

Richie, Jason. Spectacular Space Travelers. Minneapolis, MN: The Oliver Press, Inc., 2001.

Vogt, Gregory L. Suited for Spacewalking. Washington, DC: National Aeronautics and Space Administration, 1998.

Periodicals

Lucid, Shannon W. "Six Months on Mir." Scientific American. (May 1998): pp. 46-55.

Samuel, Eugenie. "Super Skin." New Scientist. (June 16, 2001): p. 24.

Web Sites

"International Space Station: Turning Science Fiction into Science Fact."

National Aeronautics and Space Administration. http://www.hq.nasa.gov/office/pao/facts/HTML/FS-004-HQ.html (accessed July 22, 2002).

Portree, David S.F. and Robert C. Treviño. Walking to Olympus: An EVA Chronology. http://spaceflight.nasa.gov/spacenews/factsheets/pdfs/EVACron.pdf (accessed on July 22, 2002).

"Women's Achievements in Aviation and Space." National Aeronautics and Space Administration. http://www.nasa.gov/hqpao/women_ac.htm (accessed on July 22, 2002).