Spacesuit
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.
EILEEN COLLINS
In 1999, Eileen Collins (1956–) became the first woman to command a spacecraft. The mission of the space shuttle Columbia was to deploy, or release, the Chandra X-ray Observatory, a huge satellite that carries a powerful telescope for studying natural phenomena, such as exploding stars, black holes, and quasars. Prior to this mission, in 1995, Collins, as the first woman to pilot a space shuttle, navigated the shuttle Discovery to within 30 feet (9 meters) of the Russian space station Mir during the first of several joint Russian-American space missions. This dress rehearsal was followed by a 1997 mission to Mir, during which Collins piloted the Atlantis, docking on Mir to deliver U.S. astronaut Mike Foale and four tons of supplies and to take U.S. astronaut Jerry Linenger back to Earth.
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.
"BENDS" PREVENTION
Before astronauts can venture out to space, they have to prebreathe pure oxygen. This is done to prevent decompression sickness called the "bends." Decompression sickness results from exposure to low atmospheric pressure, which causes the nitrogen in the blood to evaporate, forming bubbles in the blood. These bubbles interfere with blood flow, causing joint pains, cramps, paralysis, and even death. Nitrogen bubble formation will occur if the astronaut steps into the very-low-pressure environment (4.3 pounds per square inch, or 0.302 kilogram per square centimeter) of the spacesuit from the higher-pressure setting of the space cabin (the same pressure as the earth's atmosphere; 14.7 pounds per square inch, or 1.034 kilograms per square centimeter). To replace the nitrogen in the blood, before putting on their spacesuits, astronauts prebreathe oxygen through an oxygen mask attached to an oxygen supply. After their suits are on and before the pressure in the suits is lowered, the astronauts prebreathe more oxygen.
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 SpaceAdministration.http://www.nasa.gov/hqpao/women_ac.htm (accessed on July 22, 2002).
Spacesuit
Spacesuit
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.
Background
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.
History
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.
For the first space walks that occurred during the Gemini missions in 1965, a seven layer suit was used for extra protection. The extra layers were composed of aluminized Mylar, which provided more thermal protection and protection from micrometeoroids. These suits had a total weight of 33 lb (15 kg). While they were adequate, there were certain problems associated with them. For example, the face mask on the helmet quickly fogged so vision was hampered. Also, the gas cooling system was not adequate because it could not remove excessive heat and moisture quickly enough.
Sally Ride is best known as the first American woman sent into outer space. Both scientist and professor, she has served as a fellow at the Stanford University Center for International Security and Arms Control, a member of the board of directors at Apple Computer Inc., and a space institute director and physics professor at the University of California at San Diego. Ride has chosen to write primarily for children about space travel and exploration.
Sally Kristen Ride is the older daughter of Dale Burdell and Carol Joyce (Anderson) Ride of Encino, California, and was born May 26, 1951. As author Karen O'Connor describes tomboy Ride in her young reader's book, Sally Ride and the New Astronauts, Sally would race her dad for the sports section of the newspaper when she was only five years old. An active, adventurous, yet also scholarly family, the Rides traveled throughout Europe for a year when Sally was nine and her sister Karen was seven. While Karen was inspired to become a minister, in the spirit of her parents, who were elders in their Presbyterian church, Ride's own developing taste for exploration would eventually lead her to apply to the space program almost on a whim. "I don't know why I wanted to do it," she confessed to Newsweek prior to embarking on her first spaceflight.
The opportunity was serendipitous, since the year she began job-hunting marked the first time NASA had opened its space program to applicants since the late 1960s, and the very first time women would not be excluded from consideration. Ride became one of thirty-five chosen from an original field of applicants numbering eight thousand for the spaceflight training of 1978. "Why I was selected remains a complete mystery," she later admitted to John Grossmann in a 1985 interview in Health. "None of us has ever been told."
Ride would subsequently become, at thirty-one, the youngest person sent into orbit as well as the first American woman in space, the first American woman to make two space-flights, and, coincidentally, the first astronaut to marry another astronaut in active duty.
Ride left NASA in 1987 for Stanford's Center for International Security and Arms Control, and two years later she became director of the California Space Institute and physics professor at the University of California at San Diego.
The Apollo missions utilized more complicated suits that solved some of these problems. For moon walks, the astronauts wore a seven layer garment with a life-support backpack. The total weight was about 57 lb (26 kg). For the Space Shuttle missions, NASA introduced the Extravehicular Mobility Unit (EMU). This was a spacesuit designed for space walks that did not require a connection to the orbiter. One primary difference in these suits was that they were designed for multiple astronaut use instead of being custom made like the previous spacesuits. Over the last 20 years, the EMUs have undergone steady improvements however, they still look the same as they did when the shuttle program began in 1981. Currently, the EMU has 14 layers of protection and weighs over 275 lb (125 kg).
Raw Materials
Numerous raw materials are used for constructing a spacesuit. Fabric materials include a variety of different synthetic polymers. The innermost layer is made up of a Nylon tricot material. Another layer is composed of spandex, an elastic wearable polymer. There is also a layer of urethane-coated nylon, which is involved in pressurization. Dacron—a type of polyester—is used for a pressure-restraining layer. Other synthetic fabrics used include Neoprene that is a type of sponge rubber, aluminized Mylar, Gortex, Kevlar, and Nomex.
Beyond synthetic fibers other raw materials have important roles. Fiberglass is the primary material for the hard upper torso segment. Lithium hydroxide is used in making the filter which removes carbon dioxide and water vapor during a space walk. A silver zinc blend comprises the battery that powers the suit. Plastic tubing is woven into the fabric to transport cooling water throughout the suit. A polycarbonate material is used for constructing the shell of the helmet. Various other components are used to make up the electronic circuitry and suit controls.
Design
A single EMU spacesuit is constructed from various tailor-made components produced by over 80 companies. The size of the parts vary ranging from one-eighth-inch washers to a 30 inch (76.2 cm) long water tank. The EMU consists of 18 separate items. Some of the major components are outlined below.
The primary life support system is a self-contained backpack that is fitted with an oxygen supply, carbon-dioxide removal filters, electrical power, ventilating fan and communication equipment. It provides the astronaut with most of the things needed to survive such as oxygen, air purification, temperature control and communication. As much as seven hours worth of oxygen can be stored in the suit's tank. A secondary oxygen pack is also found on the suit. This provides an additional 30 minutes of emergency oxygen.
The helmet is a large plastic, pressurized bubble that has a neck ring and a ventilation distribution pad. It also has a purge valve, which is used with a secondary oxygen pack. In the helmet, there is a straw to a drink bag in case the astronaut gets thirsty, a visor which shields rays from the bright sun, and a camera which records extra vehicular activities. Since space walks can last over seven hours at a time, the suit is fitted with a urine collection system to allow for bathroom breaks. The MSOR assembly attaches to the outside of the helmet. This device (also known as a "Snoopy Cap") snaps into place with a chin strap. It consists of headphones and a microphone for two way communication. It also has four small "head lamps" which shine extra light where needed. The visor is manually adjusted to shield the astronaut's eyes.
To maintain temperature, a liquid cooling and ventilation garment is worn under the outer garment. It is composed of cooling tubes, which have fluid flowing through them. The undergarment is a mesh one-piece suit composed of spandex. It has a zipper to allow for front entry. It has over 300 ft of plastic tubing intertwined within which it circulates cool water. Normally, the circulating water is maintained from 40-50° F (4.4-9.9° C). The temperature is controlled by a valve on the display control panel. The lower garment weighs 8.4 lb (3.8 kg) when loaded with water.
The lower torso assembly is made up of the pants, boots, "brief unit, knee and ankle joints and the waist connection. It is composed of a pressure bladder of urethane-coated nylon. A restraining layer of Dacron and an outer thermal garment composed of Neoprene-coated nylon. It also has five layers of aluminized Mylar and a fabric surface layer composed of Teflon, Kevlar, and Nomex. This part of the suit 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 urine storage device is also located in this section of the suit. Old models could hold up to 950 milliliters of liquid. Currently, a disposable diaper type garment is used.
The arm assembly is adjustable just like the lower torso assembly. 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 hard upper torso is constructed with fiberglass and metal. It is where most of the suit pieces attach including the helmet, arms, life support system display, control module and lower torso. It includes oxygen bottles, water storage tanks, a sublimator, a contaminant control cartridge, regulators, sensors, valves, and a communications system. Oxygen, carbon dioxide and water vapor leave the suit through the ventilation garment near the astronaut's feet and elbows. A drinkbag in the upper torso can hold as much as 32 oz (907.2 g) of water. The astronaut can take a drink through the mouthpiece that extends into the helmet.
Chest mounted control module lets the astronaut monitor the suit's status and connect to external sources of fluids and electricity. It contains all the mechanical and electrical operating controls and also a visual display panel. A silver zinc, rechargeable battery which operates at 17 volts is used to power the suit. This control module is integrated with the warning system found in the hard upper torso to ensure that the astronaut knows the status of the suit's environment. The suit connects to the orbiter through an umbilical line. It is disconnected prior to leaving the airlock.
The white suit weighs about 275 lb (124.8 kg) on earth and has a product life expectancy of about 15 years. It is pressurized to 4.3 lb (1.95 kg) per square inch and can be recharged by hooking up directly to the orbiter. The existing spacesuits are modular so they can be shared by multiple astronauts. The four basic interchangeable sections include the helmet, the hard upper torso, the arms and the lower torso assembly. These parts are adjustable and can be resized to fit over 95% of all astronauts. Each set of arms and legs comes in different sizes which can be fine-tuned to fit the specific astronaut. The arms allow for as much as a one inch adjustment. The legs allow for up to a three inch adjustment.
It takes about 15 minutes to put on the spacesuit. To put the spacesuit on the astronaut first puts on the lower garment that contains the liquid cooling and ventilation system. The lower torso assembly is put on next with the boots being attached. Next, the astronaut slides into the upper torso unit which is mounted with the life-support backpack on a special connector in the airlock chamber. The waste rings are connected and then the gloves and helmet are put on.
The Manufacturing
Process
The manufacture of a spacesuit is a complicated process. It can be broken down into two phases of production. First the individual components are constructed. Then the parts are brought together in a primary manufacture location, such as NASA headquarters in Houston, and assembled. The general process is outline as follows.
Helmet and visor assembly
- 1 The helmet and visor may be constructed using traditional blow molding techniques. Pellets of polycarbonate are loaded into a injection-molding machine. They are melted and forced into a cavity which as the approximate size and shape of the helmet. When the cavity is opened, the primary piece of the helmet is constructed. A connecting device is added at the open end so the helmet can be fastened to the hard upper torso. The ventilation distribution pad is added along with purge valves before the helmet is packaged and shipped. The visor assembly is similarly fitted with "head lamps" and communication equipment.
Life-support systems
- 2 The life support systems are put together in a number of steps. All the pieces are fitted to the outer backpack housing. First, the pressurized oxygen tanks are filled, capped, and put into the housing. The carbon dioxide removal equipment is put together. This typically involves a filter canister that is filled with lithium hydroxide which gets attached to a hose. The backpack is then fitted with a ventilating fan system, electrical power, a radio, a warning system, and the water cooling equipment. When completely assembled, the life support system can attach directly to the hard upper torso.
Control module
- 3 The key components of the control module are built in separate units and then assembled. This modular approach allows key parts to be easily serviced if necessary. The chest mounted control module contains all of the electronic controls, a digital display and other electronic interfaces. The primary purge valve is also added to this part.
Cooling garment
- 4 The cooling garment is worn inside the pressure layers. It is made out of a combination of nylon, spandex fibers and liquid cooling tubes. The nylon tricot is first cut into a long underwear-like shape. Meanwhile, the spandex fibers are woven into a sheet of fabric and cut into the same shape. The spandex is then fitted with a series of cooling tubes and then sewn together with the nylon layer. A front zipper is then attached as well as connectors for attachment to the life support system.
Upper and lower torso
- 5 The lower torso, arm assembly, and gloves are made in a similar manner. The various layers of synthetic fibers are woven together and then cut into the appropriate shape. Connection rings are attached at the ends and the various segments are attached. The gloves are fitted with miniature heaters in every finger and covered with insulation padding.
- 6 The hard upper torso is forged using a combination of fiberglass and metal. It has four openings where the lower torso assembly, the two arms, and the helmet attach. Additionally, adapters are added where the life support pack and the control module can be attached.
Final assembly
- 7 All the parts are shipped to NASA to be assembled. This is done on the ground where the suit can be tested prior to use in space.
Quality Control
The individual suppliers conduct quality control tests at each step of the production process. This ensures that every part is made to exacting standards and will function in the extreme environment of space. NASA also conducts extensive tests on the completely assembled suit. They check for things such as air leakage, depressurization, or nonfunctional life support systems. The quality control testing is crucial because a single malfunction could have dire consequences for an astronaut.
The Future
The current EMU design is the result of many years of research and development. While they are a powerful tool for orbital operations, many improvements are possible. It has been suggested that the spacesuit of the future may look dramatically different than the current suit. One area that can be improved is the development of suits that can operate at higher pressures than the current EMU. This would have the advantage of reducing time currently required for prebreathing prior to a space walk. To make higher pressure suits improvements will have to be made in the connecting joints on each part of the suit. Another improvement can be in the resizing of the suit in orbit. Currently, it takes a significant amount of time to remove or add extending inserts in the leg and arm areas. One other possible improvement is in the electronic controls of the suit. What now requires complex command codes will be done with the push of a single button in the future.
Where to Learn More
Books
Suited for Spacewalking. NASA, 1998.
Other
Hamilton-Standard Company. http://www.hamilton-standard.com/.
—PerryRomanowski