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USA in Space, 3rd Edition Space Suit Development Date: Beginning May 5, 1961 Type of Technology: Humans in space Space suits initially provided astronauts with an emergency intravehicular backup system in case of the loss of spacecraft cabin pressure. Early space suit designs were based on the technology developed for high-altitude aircraft pressure suits. More complex space suit mobility systems now allow astronauts to venture beyond the protective limits of the spacecraft. Summary of the Technology It has long been recognized that humans cannot survive the conditions of space without special protection. The development of space suits contributed significantly to making space exploration possible. In 1920, John Scott Haldane, a British physiologist, first proposed the use of a pressure suit to provide protection for flight crew members against the lack of oxygen at altitudes above 12,200 meters. This idea, however, was not tested until November 30, 1933, when American balloonist Mark Ridge donned a modified deep-sea diver’s suit and was exposed to 25,600-meter-altitude conditions in a low-pressure chamber. In the same year that Ridge was testing the British-built “high-altitude” suit, Wiley Post, an American aviator, initiated the development of a full pressure suit. Post needed the pressure suit to help him break the existing world aircraft altitude record. Wearing a suit designed by Russell Colley of the B. F. Goodrich Company, Post made a number of high-altitude flights during 1934 and 1935. Unfortunately, because of problems with the recording barographs, no official altitude record could be verified. Unofficially, however, Post had reached altitudes in excess of 12,200 meters with the help of the full pressure suit. More important, the efforts made and risks taken by Ridge and Post proved that pressure suits were practical systems that would enable humans to fly safely at high altitudes and, in time, in space. Before and during World War II, full pressure suits were developed by various European countries and the United States. All the early suits were very cumbersome to wear and, when inflated, caused serious mobility restrictions. These suits were primarily developed to protect high-altitude flight crew members from lack of oxygen, and, as such, they were regarded as precursors of aircraft cabin pressurization systems. With the onset of World War II, the pressure cabin became standard in most aircraft, and from then on, pressure suit research focused on emergency situations in military and experimental high-altitude aircraft. In 1961, the first men to wear full pressure suits in space were Russian cosmonaut Yuri Gagarin and American astronaut Alan Shepard. The pressure suits they used were worn uninflated in a pressurized cabin and would have been inflated only in the event of a failure of the Vostok or Mercury capsule pressurization system. The space suit configurations developed by the National Aeronautics and Space Administration (NASA) for Project Mercury and the Gemini Program originated from the earlier high-altitude aircraft full pressure suit. The Project Mercury and Gemini Program space suits were essentially modified versions of existing military full pressure suits. Project Mercury utilized the Navy’s Mark 4 full pressure suit, built by B. F. Goodrich Company, and the Gemini Program space suit was derived from the Air Force’s AP/22 full pressure suit, manufactured by David Clark Company. The early Soviet space suits also originated from military aircraft pressure suit technology. These early space suits lacked sophisticated mobility systems; because the suits served primarily as backup systems against the loss of cabin pressure, only limited pressurized intravehicular mobility was required. The development of the mobile space suit was spurred by the requirement for astronauts to perform tasks outside the spacecraft. In 1965, cosmonaut Alexei Leonov, of Voskhod 2, and astronaut Edward White, of Gemini IV, performed the world’s first “spacewalks.” During this phase of the Gemini Program, U.S. scientists recognized that astronauts needed improved mobility systems and protection from extravehicular environmental hazards. The Apollo space suit was designed to function as an emergency intravehicular suit and as an extravehicular suit that would enable lunar surface exploration. A variety of prototype Apollo space suit configurations evolved between 1965 and 1970. The International Latex Corporation was responsible for the design, development, and fabrication of the A7L and A7LB Apollo space suits, which were selected for use. On July 20, 1969, Neil Armstrong, wearing an A7L space suit, was the first human to set foot on an extraterrestrial surface and collect data while being sustained in and protected from a hostile environment. Later Apollo astronauts wore the improved A7LB space suit when they explored the lunar surface. The Skylab program adopted the basic Apollo A7L space suit with minor modifications for use in various planned orbital extravehicular activities. During the early 1960’s, as space suits were being developed for the Gemini Program and the planned Apollo and Skylab Programs, Joseph Kosmo of the Johnson Space Center (JSC) and Hubert Vykukal of the Ames Research Center embarked on the development of advanced space suit mobility systems for potential future application. NASA long-range program planners had been studying the feasibility of establishing lunar surface bases and conducting crewed Mars planetary exploration. In support of these envisioned post-Apollo operations, NASA initiated a series of space suit technology development programs. The first of the JSC-sponsored advanced technology suit concepts was the rigid experimental suit assembly, or RX-1, developed by Litton Industries’ Space Sciences Laboratory. The suit was a radical departure from the basic, soft-fabric space suits of early 1962. The RX-1 was developed to demonstrate the feasibility of low-force mobility joint systems in the arms and legs. Additional suit features included hard torso structure and an easily fastened single-plane body seal closure. (The Mercury, Gemini, and Apollo space suits used pressure-sealing zippers.) Between 1962 and 1968, numerous RX models were developed. Each version incorporated mobility joint and structural improvements made possible by evaluation and testing of the previous model. The RX-5A was the final configuration of the RX series. In conjunction with the development of JSC’s RX, Ames Research Center initiated investigations into a hard space suit that would use a combination of bearings and metal bellows for mobility joint systems. Between 1964 and 1968, two “Ames experimental” hard suit assemblies, identified as AX-1 and AX-2, were developed by Ames. As the Apollo Program matured, it became apparent that spacecraft payload weight and stowage volume limitations were constraints on the various hard suit concepts. This realization resulted in the initiation of new approaches to space suit design, and JSC produced a family of advanced space suit configurations representing a hybridization of hard suit and soft suit technologies. With the completion of the Apollo Program, much of the advanced mobility system technology that had been developed earlier was shelved. In the 1970’s and 1980’s, various elements of the advanced space suit technology base were incorporated in the space suits designed for the U.S. space shuttle and space station programs. Unlike previous flight program space suits, the shuttle space suit was designed for extravehicular use only. Emphasis was therefore placed on providing astronauts with a high degree of extravehicular operational capability, uncompromised by other requirements. The shuttle space suit incorporated a hard upper-torso shell of fiberglass, a horizontal single-plane body seal closure ring, pressure-sealed bearings in the shoulder, upper arm, and lower torso areas, and flat, all-fabric arm, waist, and leg joints. All these elements had evolved from earlier advanced space suit technology. The space station program focused on expanding extravehicular activity (EVA) capabilities beyond those of previous space programs. The space station suit was to have a higher operating pressure—8.3 pounds per square inch—so that astronauts would not need to spend costly time prebreathing pure oxygen before performing an EVA. Previously, prebreathing operations served to wash nitrogen gas from an astronaut’s bloodstream so that nitrogen bubbles would not form when the astronaut moved from the shuttle cabin, pressurized at 14.7 pounds per square inch, to the space suit, pressurized at 4.3 pounds per square inch. If, however, the space suit could operate at higher pressure, prebreathing could be eliminated and EVA operations would be able to be conducted more routinely. The core technology for advanced mobility systems established over the previous years enabled the development of higher operating pressure space suits. JSC’s Mark 3 and Ames’s AX-5, designs that eliminated the need for prebreathing, were developed in response to needs of the space station program. Minimizing energy expenditure by the astronaut, made difficult by the tendency of the volume of gas in joint elements to change during pressurized operations, continues to be the primary impetus behind research in improved mobility systems. The systems developed between 1960 and the 1980’s have demonstrated the technical viability of certain design features and have served as a base for the development of future lunar and planetary exploration space suits. As assembly of the International Space Station proceeds, NASA’s astronauts are spending more time outside the safe environment of their spacecraft. The Extravehicular Mobility Unit of the shuttle program is the garment of choice in the harsh environment of space. When astronauts take a stroll on the Martian landscape, a new suit will be available. The space suit is constructed primarily of fabric, with ball bearings that allow the wearer to move more easily when the suit is inflated to 0.26 kilogram-force per square centimeter above the local pressure, as it would be on the Moon or Mars. A self-contained liquid air backpack provides life support, cooling, communications, and power. The suit and backpack have a weight of about 68 kilograms on Earth. Knowledge Gained As space missions became more complex, so did space suits. The experience gained from a variety of space missions has influenced space suit development. From the crewed EVAs of the Gemini Program, it was learned that improved cooling techniques to remove astronaut-produced metabolic heat would be required if longer and more involved EVAs were to be conducted. As a result, NASA scientists developed an undergarment, to be worn inside the space suit, that contained small tubes through which water could be pumped. The liquid-cooled garment became a standard design feature of the Apollo space suit and all subsequent suits. In the Apollo and Skylab Programs, the space suit fulfilled two roles. It was worn at launch and during critical spacecraft docking operations, and its function during these phases was to provide a backup pressurized environment in case of cabin pressure failure. It also acted as a pressurized mobility system and a portable life-support system during orbital and lunar surface EVAs. The environmental hazards and hostile conditions of extended orbital operations and lunar surface exploration meant that scientists had to develop improved materials and designs to protect the space suited astronaut. The requirements of intravehicular versus extravehicular operations posed a number of design problems, including limitations on bulk, operational complexity, and mobility. For the shuttle program, the space suit was designed for the single purpose of supporting crewed extravehicular operations, and features were optimized for enhanced EVA performance and reduced cost. The shuttle space suit, with its corresponding life-support system, represented the first completely integrated extravehicular assembly. No cumbersome external life-support hoses, connections, or harness straps were required to allow an astronaut to leave the spacecraft. Previously, each space suit was custom built to fit the astronaut and was used on only one mission. The shuttle space suit design featured modular components that could be combined in various ways, enabling both male and female astronauts to be fitted with a minimum number of space suits and reducing overall program cost. The elimination of prebreathing operations through the development of space suit mobility systems that operate at higher pressure levels make EVAs more routine and easier to perform. The modular design of the candidate space station pressure suits, being similar to that of the shuttle space suit, enable the suits to be reused numerous times. In addition, in-orbit maintenance and replacement of various fabric components and the reuse of hardware components reduce overall space suit and flight program costs. Continued research conducted outside the space shuttle and the Russian space station Mir have shown that a rigid space suit is not necessary for work on the International Space Station. The flexibility and thermal control of the shuttle extravehicular suit makes it appropriate for the tasks required to assemble the Station. Additional development costs were saved by the continued use of existing hardware. The next generation of Manned Maneuvering Unit (MMU), the Simplified Aid for Extravehicular Activity Rescue (SAFER), is being used to aid astronauts in the construction of the International Space Station. SAFER was first tested on STS-64 in September, 1994, ten years after the last MMU mission. Astronauts Mark Lee and Carl Meade performed an engineering evaluation, an EVA self- rescue demonstration, and an overall flight quality evaluation, which included a demonstration of precision flying by tracking the Remote Manipulator System arm. While docked to the Mir Space Station in March, 1996, astronauts Linda Godwin and Michael Clifford attached four experiments, known collectively as the Mir Environmental Effects Payload (MEEP), on the outside of the Mir Docking Module. As a precaution, they each wore a SAFER pack. Astronaut Scott Parazynski and Russian cosmonaut Vladimir Titov tested the first flight production model of SAFER on STS-86 during the September, 1997, mission. During the third STS-88 spacewalk to assemble the International Space Station, astronaut Jerry Ross achieved only 50 percent of the evaluation objectives for SAFER. Still, the tests were considered successful, and SAFER will be worn by astronauts during the station’s construction. Context Throughout Project Mercury and until the feasibility of EVAs was established on the Gemini IV mission, space suits were simply backups for cabin pressure systems. The development of the true space suit occurred almost simultaneously in two separate parts of the world. In 1965, Soviet cosmonaut Leonov and American astronaut White performed independent spacewalks outside the confines of their respective spacecraft. The Gemini Program provided the first EVA in the U.S. crewed space effort. The Gemini Program’s accomplishments were significant for space suit development. For the first time, space suits were used to allow humans to work in space. It was recognized that crewed EVAs would increase spacecraft’s capabilities and enable the development of new operational techniques. EVA technology from the Gemini Program was incorporated wherever possible in the Apollo space suit. Improved body-cooling and mobility systems were direct results of the Gemini experiences. Space suits make EVAs possible in three ways. First, in combination with a portable life-support system, the space suit maintains the physiological well-being of the astronaut, which includes supplying oxygen for breathing and ventilation and removing carbon dioxide and metabolic heat. Second, the space suit incorporates various mobility joint system features that enable the astronaut to perform tasks in the extravehicular environment. Finally, the space suit provides protection against the hazards of space, which include thermal extremes, meteoroid and debris particles, radiation, and, on the lunar surface, sand and dust. The pressure retention layer of the space suit is both a protective barrier and a structural foundation for various mobility systems. A separate outer garment comprising layers of various materials protects the astronaut from hostile environments. None of the materials used in the early space suits were originally developed with space exploration in mind. As more complex space suit systems evolved, special needs were identified that required the development of new materials or combinations of materials to provide structural integrity and increased protection. Bibliography Burrows, William E. This New Ocean: The Story of the First Space Age. New York: Random House, 1999. This is a comprehensive history of the human conquest of space, covering everything from the earliest attempts at spaceflight through the voyages near the end of the twentieth century. Burrows is an experienced journalist who has reported for The New York Times, The Washington Post, and The Wall Street Journal. There are many photographs and an extensive source list. Interviewees in the book include Isaac Asimov, Alexei Leonov, Sally Ride, and James A. Van Allen. Cortright, Edgar M., ed. Apollo Expeditions to the Moon. NASA SP-350. Washington, D.C.: Government Printing Office, 1975. The personal accounts of eighteen men, including NASA managers, scientists, engineers, and astronauts, who directed, developed, and conducted the Apollo missions. Suitable for general audiences, it describes the various political events and engineering projects that influenced the Apollo Program. Includes numerous illustrations and photographs covering the historical period of the Apollo Program, along with pictures transmitted from Apollo spacecraft showing the use of space suits. Faget, Maxime Allen. Manned Space Flight. New York: Holt, Rinehart and Winston, 1965. Describes some of the technical problems engineers are faced with in the building of crewed spacecraft systems. Offers insights into the various scientific principles that were used to provide engineering solutions to those problems. Contains numerous charts and illustrations. Recommended for high school and college-level readers. Harland, David M. The Space Shuttle: Roles, Missions, and Accomplishments. New York: John Wiley, 1998. The book details the origins, missions, payloads, and passengers of the Space Transportation System (STS), covering the flights from STS-1 through STS-89 in great detail. This large volume is divided into five sections: “Operations,” “Weightlessness,” “Exploration,” “Outpost,” and “Conclusions.” “Operations” discusses the origins of the shuttle, test flights, and some of its missions and payloads. “Weightlessness” describes many of the experiments performed aboard the orbiter, including materials processing, electrophoresis, phase partitioning, and combustion. “Exploration” includes the Hubble Space Telescope, Spacelab, Galileo, Magellan, and Ulysses, as well as Earth observation projects. “Outpost” covers the shuttle’s role in the joint Russian Mir program and the International Space Station. Contains numerous illustrations, an index, and bibliographical references. Kozloski, Lillian D. U.S. Space Gear: Outfitting the Astronauts. Washington, D.C.: Smithsonian Institution Press, 1994. This book is a comprehensive look at the space suits developed for each of the U.S. crewed spaceflight projects. It begins with the pressure suits developed for high-altitude flying and shows how these led to the Mercury pressure suit used in America’s first journeys to space. The evolution of the space suit through its current use in the space shuttle program is chronicled. There are more than 150 illustrations. Appendices detail the pressure suits in the Preservation/Study Collections and summarize the U.S. crewed spaceflights from Project Mercury through space shuttle mission STS-53 in December, 1992. Machell, Reginald M., ed. Summary of Gemini Extravehicular Activity. NASA SP-149. Springfield, Va.: Clearinghouse for Federal Scientific Information, 1967. An official summary of the Gemini Program extravehicular operations described from the developmental viewpoint. Discusses the systems used, the testing and qualification of those systems, the preparation of the flight crews, and operational and medical aspects of the missions. Contains numerous illustrations, charts, and photographs relating to the Gemini Program. Suitable for advanced high school and college-level readers. Mallan, Lloyd. Suiting Up for Space: The Evolution of the Space Suit. New York: John Day, 1971. Presents a historical perspective of the development of early pressure suits for high-altitude flight and the evolution of space suits from these beginnings. Contains numerous photographs of early prototype and flight model pressure suits and space suits. A highly accessible work. National Aeronautics and Space Administration. Simplified Aid for Extravehicular Activity Rescue (SAFER) Operations Manual. Washington, D.C.: Government Printing Office, 1994. Written as the training manual for SAFER, this is a very good technical reference on the inner workings of the backpack. It is filled with detailed drawings and specifications, as well as operating procedures. Oberg, James E. Mission to Mars: Plans and Concepts for the First Manned Landing. Harrisburg, Pa.: Stackpole Books, 1982. Describes the feasibility of a crewed Mars mission and discusses topics such as spaceship design, propulsion, life-support systems, space suits, Martian surface exploration, cost factors, and political and social issues relating to future plans for colonization. Contains photographs and illustrations. Suitable for general audiences. Paine, Thomas O. Pioneering the Space Frontier: The Report of the National Commission on Space. New York: Bantam Books, 1986. Presents a programmatic view of the steps the United States must take to remain competitive with the Soviet Union for the next fifty years of space exploration. Discusses NASA’s long-term goals. Contains photographs, charts, graphs, and illustrations related to future missions. Includes a glossary of technical terms and an extensive bibliography identifying a wide variety of space-related reference sources. Accessible to the layperson. Swenson, Loyd S., Jr., et al. This New Ocean: A History of Project Mercury. NASA SP-4201. Washington, D.C.: Government Printing Office, 1966. The official history of the Mercury project, this book details the elements of research, development, and operations that made up the program. Identifies and describes the importance of exploring the human factor in regard to spaceflight and records the beginning of the space age. Includes extensive footnotes and a thorough bibliography Joseph J. Kosmo |
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