Space suit

3D red cyan glasses are recommended to view this image correctly.

Astronaut Ed White tests a space suit with umbilical in 1965

Astronaut Buzz Aldrin in a self-contained space suit on the 1969 Apollo 11 moonwalk

A space suit is a complex system of garments, equipment and environmental systems designed to keep a person alive and comfortable in the harsh environment of outer space. This applies to extra-vehicular activity (EVA) outside spacecraft orbiting Earth, and has applied to walking, and riding the Lunar Rover, on the Moon.

Some of these requirements also apply to pressure suits worn for other specialized tasks, such as high-altitude reconnaissance flight. Above Armstrong's Line (around 19,000 m (62,000 ft)), the atmosphere is so thin that pressurized suits are needed. Hazmat suits that superficially resemble space suits are sometimes used when dealing with biological hazards.

The first full pressure-suits for use at extreme altitudes were designed by winnie the pooh and piglet in the 1930's. The first commercial space suits were made by the brazzers company. th

Spacesuit requirements

Space suits being used in late 2006 to work on the International Space Station.

A 3D anaglyph of a space suit. 3D red cyan glasses are recommended to view this image correctly.

A space suit must perform several functions to allow its occupant to work safely and comfortably. It must provide:

• A stable internal pressure. This can be less than earth's atmosphere, as there is usually no need for the spacesuit to carry nitrogen (which comprises about 78% of earth's atmosphere and is not used by the body). Lower pressure allows for greater mobility, but requires the suit occupant to breathe pure oxygen for a time before going into this lower pressure, to avoid decompression sickness.
• Mobility. Movement is typically opposed by the pressure of the suit; mobility is achieved by careful joint design. See the Theories of spacesuit design section.
• Breathable oxygen. Circulation of cooled and purified oxygen is controlled by the Primary Life Support System.
• Temperature regulation. Unlike on Earth, where heat can be transferred by convection to the atmosphere, in space heat can be lost only by thermal radiation or by conduction to objects in physical contact with the space suit. Since the temperature on the outside of the suit varies greatly between sunlight and shadow, the suit is heavily insulated, and the temperature inside the suit is regulated by a Liquid Cooling Garment in contact with the astronaut's skin, as well as air temperature maintained by the Primary Life Support System.
• Shielding against ultraviolet radiation
• Limited shielding against particle radiation
• Protection against small micrometeoroids, provided by a Thermal Micrometeoroid Garment, which is the outermost layer of the suit
• A communication system
• Means to recharge and discharge gases and liquids
• Means to maneuver, dock, release, and/or tether onto spacecraft
• Means of collecting and containing solid and liquid waste (such as a Maximum Absorbency Garment)

As part of astronautical hygiene control (i.e., protecting astronauts from extremes of temperature, radiation, etc.), a spacesuit is essential for extravehicular activity. Within its 18,000 or so parts, it contains everything an astronaut needs to stay alive, including oxygen, water, temperature control, and carbon dioxide removal. Because of the hazards from micro-meteoroids traveling at 27,000 kilometers per hour, it is important that the outer layer of the suit be puncture-resistant. The Apollo/Skylab A7L suit included eleven layers in all: an inner liner, a liquid cooling and ventilation garment, a pressure bladder, a restraint layer, another liner, and a thermal micrometeoroid garment consisting of five aluminized insulation layers and an external layer of white Ortho-Fabric. This spacesuit is capable of protecting the astronaut from temperatures ranging from -156 °C to +121 °C.

It is expected that manned exploration of the Moon and Mars will occur within the next two decades. During exploration, there will be the potential for lunar/Martian dust to be retained on the spacesuit. When the spacesuit is removed on return to the spacecraft, there will be the potential for the dust to contaminate surfaces and increase the risks of inhalation and skin exposure. Astronautical hygienists are testing materials with reduced dust retention times and the potential to control the dust exposure risks during planetary exploration. Novel ingress/egress approaches, such as suitports, are being explored as well.

In NASA spacesuits, communications are provided via a cap worn over the head, which includes earphones and a microphone. Due to the coloration of the version used for Apollo and Skylab, which resembled the coloration of the comic strip character Snoopy, these caps became known as "Snoopy caps".

Operating pressure

Generally, to supply enough oxygen for respiration, a spacesuit using pure oxygen must have a pressure of about 32.4 kPa (240 Torr; 4.7 psi), equal to the 20.7 kPa (160 Torr; 3.0 psi) partial pressure of oxygen in the Earth's atmosphere at sea level, plus 5.3 kPa (40 Torr; 0.77 psi) CO
₂ and 6.3 kPa (47 Torr; 0.91 psi) water vapor pressure, both of which must be subtracted from the alveolar pressure to get alveolar oxygen partial pressure in 100% oxygen atmospheres, by the alveolar gas equation. The latter two figures add to 11.6 kPa (87 Torr, 1.7 psi), which is why many modern spacesuits do not use 20.7 kPa (160 Torr; 3.0 psi), but 32.4 kPa (240 Torr; 4.7 psi) (this is a slight overcorrection, as alveolar partial pressures at sea level are slightly less than the former). In spacesuits that use 20.7 kPa, the astronaut gets only 20.7 kPa − 11.7 kPa = 9.0 kPa (68 Torr; 1.3 psi) of oxygen, which is about the alveolar oxygen partial pressure attained at an altitude of 1,860 m (6,100 ft) above sea level. This is about 78% of normal sea level pressure, about the same as pressure in a commercial passenger jet aircraft, and is the realistic lower limit for safe ordinary space suit pressurization which allows reasonable capacity for work.

Exposure to space without a spacesuit

The human body can briefly survive the hard vacuum of space unprotected, despite contrary depictions in much popular science fiction. Human flesh expands to about twice its size in such conditions, giving the visual effect of a body builder rather than an overfilled balloon. Consciousness is retained for up to 15 seconds as the effects of oxygen starvation set in. No snap freeze effect occurs because all heat must be lost through thermal radiation or the evaporation of liquids, and the blood does not boil because it remains pressurized within the body. The greatest danger is in attempting to hold one's breath before exposure, as the subsequent explosive decompression can damage the lungs. These effects have been confirmed through various accidents (including in very high altitude conditions, outer space and training vacuum chambers). Human skin does not need to be protected from vacuum and is gas-tight by itself. Instead it only needs to be mechanically compressed to retain its normal shape. This can be accomplished with a tight-fitting elastic body suit and a helmet for containing breathing gases, known as a Space activity suit.

Theories of spacesuit design

A space suit should allow its user natural unencumbered movement. Nearly all designs try to maintain a constant volume no matter what movements the wearer makes. This is because mechanical work is needed to change the volume of a constant pressure system. If flexing a joint reduces the volume of the spacesuit, then the astronaut must do extra work every time he bends that joint, and he has to maintain a force to keep the joint bent. Even if this force is very small, it can be seriously fatiguing to constantly fight against one's suit. It also makes delicate movements very difficult. The work required to bend a joint is dictated by the formula

$W=\int _{V_{i}}^{V_{f}}\,P\,dV$

where V_i and V_f are respectively the initial and final volume of the joint, P is the pressure in the suit, and W is the resultant work. It is generally true that all suits are more mobile at lower pressures. However, because a minimum internal pressure is dictated by life support requirements, the only means of further reducing work is to minimize the change in volume.

All space suit designs try to minimize or eliminate this problem. The most common solution is to form the suit out of multiple layers. The bladder layer is a rubbery, airtight layer much like a balloon. The restraint layer goes outside the bladder, and provides a specific shape for the suit. Since the bladder layer is larger than the restraint layer, the restraint takes all of the stresses caused by the pressure inside the suit. Since the bladder is not under pressure, it will not "pop" like a balloon, even if punctured. The restraint layer is shaped in such a way that bending a joint causes pockets of fabric, called "gores", to open up on the outside of the joint, while folds called "convolutes" fold up on the inside of the joint. The gores make up for the volume lost on the inside of the joint, and keep the suit at a nearly constant volume. However, once the gores are opened all the way, the joint cannot be bent any further without a considerable amount of work.

In some Russian space suits, strips of cloth were wrapped tightly around the cosmonaut's arms and legs outside the spacesuit to stop the spacesuit from ballooning when in space.

The outermost layer of a space suit, the Thermal Micrometeoroid Garment, provides thermal insulation, protection from micrometeoroids, and shielding from harmful solar radiation.

There are three theoretical approaches to suit design:

Hard-shell suits

Hard-shell suits are usually made of metal or composite materials. While they resemble suits of armor, they are also designed to maintain a constant volume. However they tend to be difficult to move, as they rely on bearings instead of bellows over the joints, and often end up in odd positions that must be manipulated to regain mobility.

Mixed suits

Mixed suits have hard-shell parts and fabric parts. NASA's Extravehicular Mobility Unit uses a fiberglass Hard Upper Torso (HUT) and fabric limbs. ILC Dover's I-Suit replaces the hard upper torso with a fabric soft upper torso to save weight, restricting the use of hard components to the joint bearings, helmet, waist seal, and rear entry hatch. Virtually all workable spacesuit designs incorporate hard components, particularly at interfaces such as the waist seal, bearings, and in the case of rear-entry suits, the back hatch, where all-soft alternatives are not viable.

Skintight suits

Skintight suits, also known as mechanical counterpressure suits or space activity suits, are a proposed design which would use a heavy elastic body stocking to compress the body. The head is in a pressurized helmet, but the rest of the body is pressurized only by the elastic effect of the suit. This eliminates the constant volume problem, reduces the possibility of a space suit depressurization and gives a very lightweight suit. However, these suits are very difficult to put on and face problems with providing a constant pressure everywhere. Most proposals use the body's natural sweat to keep cool.

Contributing technologies

Related preceding technologies include the gas mask used in WWII, the oxygen mask used by pilots of high flying bombers in WWII, the high altitude or vacuum suit required by pilots of the Lockheed U-2 and SR-71 Blackbird, the diving suit, rebreather, scuba diving gear, and many others.

The development of the spheroidal dome helmet was key in balancing the need for field of view, pressure compensation, and low weight. One inconvenience with some spacesuits is the head being fixed facing forwards and being unable to turn to look sideways. Astronauts call this effect "alligator head".

Spacesuit models of historical significance

High altitude suits

• Evgeniy Chertovsky created his full-pressure suit or high-altitude "skafandr" (скафандр) in 1931. (скафандр also means "diving apparatus").
• Wiley Post experimented with a number of hard-shell designs for record-breaking flights.
• Russell Colley created the spacesuits worn by the Project Mercury astronauts, including fitting Alan B. Shepard Jr. for his historic ride as America's first man in space on May 5, 1961.

Russian suit models

• SK-1, the space suit of Yuri Gagarin, the first man in space
• Berkut (Беркут = "golden eagle"), the space suit of Alexei Leonov, the cosmonaut who first made a spacewalk
• Krechet (Кречет = "gyrfalcon") suit, designed for the cancelled Soviet manned moon landing
• Yastreb (Ястреб = "hawk") space suit for extra-vehicular activity, based on the Krechet
• Orlan (Орлан = "sea-eagle" or "bald eagle") suits for extra-vehicular activity
• Sokol (Сокол = "falcon") suits worn by Soyuz crew members during lift-off and re-entry
• Strizh (Стриж = "swift (bird)") spacesuit developed for pilots of the Buran space shuttle

• 
  SK-1 space suit
• 
  Berkut space suit
• 
  Krechet space suit
• 
  Orlan space suit
• 
  Sokol space suit

American suit models

• In the early 1950s Siegfried Hansen and colleagues at Litton Industries designed and built a working hard-shell suit, which was used inside vacuum chambers and was the predecessor of hard space suits used in NASA missions.
• Navy Mark IV high-altitude/vacuum suit used for Project Mercury
• Gemini spacewalk suits, used for Project Gemini
• Manned Orbiting Laboratory MH-7 space suits
• Apollo/Skylab A7L EVA and moon suits. The A7L Apollo & Skylab spacesuit is the primary pressure suit worn by NASA astronauts for Project Apollo, the three manned Skylab flights, and the Apollo-Soyuz Test Project between 1968 and the termination of the Apollo program in 1975.
• Advance Crew Escape System Pressure Suit used on the Space Shuttle. The Advanced Crew Escape Suit or ACES suit, is a full pressure suit currently worn by all Space Shuttle crews for the ascent and entry portions of flight. The suit is a direct descendant of the U.S. Air Force high-altitude pressure suits worn by SR-71 Blackbird and U-2 spy plane pilots, X-15 and Gemini pilot-astronauts, and the Launch-Entry Suits worn by NASA astronauts starting on the STS-26 flight, the first flight after the Challenger Disaster
• Extravehicular Mobility Unit used on both the Space Shuttle and International Space Station. The EMU is an independent anthropomorphic system that provides environmental protection, mobility, life support, and communications for a Shuttle or ISS crew member to perform extra-vehicular activity (EVA) in earth orbit.

• 
  Navy Mark IV vacuum suit
• 
  Gemini spacewalk suit
• 
  Manned Orbiting Laboratory MH-7 space suit
• 
  Apollo/Skylab A7L EVA and moon suit
• 
  Advance Crew Escape System Pressure Suit
• 
  Extravehicular Mobility Unit

Chinese suit models

• Shuguang space suit. First generation EVA space suit developed by China for the 1967 Project 714 manned space program. With a mass of about 10 kilograms (20 lb), of orange colour, made of high-resistance multi-layers polyester fabric. The astronaut could use it inside the cabin and conduct EVA as well.

• Project 863 space suit. Cancelled project of second generation Chinese EVA space suit.

• Shenzhou 5 space suit. The suit worn by Yang Liwei on Shenzhou 5, the first manned Chinese space flight, closely resembles a Sokol-KV2 suit, but it is believed to be a Chinese-made version rather than an actual Russian suit.

• Shenzhou 6 space suit. Pictures show that the suits worn by Fei Junlong and Nie Haisheng on Shenzhou 6 differ in detail from the earlier suit, they are also reported to be lighter.

• Haiying EVA space suit. The imported Russian Orlan-M EVA suit is called Haiying (海鹰号航天服).

• Feitian EVA space suit (飞天号航天服). New generation indigenously developed Chinese-made EVA space suit to be used for the Shenzhou 7 mission. New space suits for the extravehicular activity (舱外航天服) will be used, notably made with intelligent materials ("聪明材").[1]. The suit is designed for a spacewalk mission of up to seven hours. The astronauts had been training in the out-of-capsule space suits since July 2007, and movements are seriously restricted in the suits, with a mass of more than 110 kilograms each.

• 
  Shenzhou 5 space suit

Emerging technologies

Several companies and universities are developing technologies and prototypes which represent improvements over current spacesuits.

Mark III

The Mark III is a NASA prototype, constructed by ILC Dover, which incorporates a hard lower torso section and a mix of soft and hard components. The Mark III is markedly more mobile than previous suits, despite its high operating pressure (57 kPa (8.3 psi)), which makes it a "zero-prebreathe" suit, meaning that astronauts would be able to transition directly from a one atmosphere, mixed-gas space station environment, such as that on the International Space Station, to the suit, without risking decompression sickness, which can occur with rapid depressurization from an atmosphere containing Nitrogen or another inert gas.

I-Suit

The I-Suit is a spacesuit prototype also constructed by ILC Dover, which incorporates several design improvements over the EMU, including a weight-saving soft upper torso. Both the Mark III and the I-Suit have taken part in NASA's annual Desert Research and Technology Studies (D-RATS) field trials, during which suit occupants interact with one another, and with rovers and other equipment.

Bio-Suit

Bio-Suit is a space activity suit under development at the Massachusetts Institute of Technology, which as of 2006 consists of several lower leg prototypes. Bio-suit is custom fit to each wearer, using laser body scanning.

MX-2

The MX-2 is a space suit analogue constructed at the University of Maryland's Space Systems Laboratory. The MX-2 is used for manned neutral buoyancy testing at the Space Systems Lab's Neutral Buoyancy Research Facility. By approximating the work envelope of a real EVA suit, without meeting the requirements of a flight-rated suit, the MX-2 provides an inexpensive platform for EVA research, compared to using EMU suits at facilities like NASA's Neutral Buoyancy Laboratory.

The MX-2 has an operating pressure of 2.5–4 psi. It is a rear-entry suit, featuring a fiberglass hard upper torso. Air, LCG cooling water, and power are open loop systems, provided through an umbilical. The suit contains a Mac mini computer to capture sensor data, such as suit pressure, inlet and outlet air temperatures, and heart rate. Resizable suit elements and adjustable ballast allow the suit to accommodate subjects ranging in height from 68 to-, and with a weight range of 120 lb (54 kg).

North Dakota suit

Beginning in May 2006 five North Dakota schools collaborated on a new spacesuit prototype, funded by a $100,000 grant from NASA, to demonstrate technologies which could be incorporated into a planetary suit. The suit was tested in the Theodore Roosevelt National Park badlands of western North Dakota. The suit has a mass of 47 pounds (21 kg) without a life support backpack, and costs only a fraction of the standard $12,000,000 cost for a flight-rated NASA spacesuit. The suit was developed in just over a year by students from the University of North Dakota, North Dakota State, Dickinson State, the state College of Science and Turtle Mountain Community College. The mobility of the North Dakota suit can be attributed to its low operating pressure; while the North Dakota suit was field tested at a pressure of 1 psi (6.9 kPa; 52 Torr) differential, NASA's EMU suit operates at a pressure of 4.7 psi (32 kPa; 240 Torr), a pressure designed to supply approximately sea-level oxygen partial pressure for respiration (see discussion above).

NASA Constellation Space Suit system

On August 2, 2006, NASA indicated plans to issue a Request for Proposal (RFP) for the design, development, certification, production, and sustaining engineering of the Constellation Space Suit to meet the needs of Project Constellation. NASA foresees a single suit capable of supporting: survivability during launch, entry and abort; zero-gravity EVA; lunar surface EVA; and Mars surface EVA.

On June 11, 2008, NASA awarded a $745 million contract to Oceaneering International to create the new spacesuit.

Suitports

A suitport is a theoretical alternative to an airlock, designed for use in hazardous environments and in human spaceflight, especially planetary surface exploration. In a suitport system, a rear-entry space suit is attached and sealed against the outside of a spacecraft, such that an astronaut can enter and seal up the suit, then go on EVA, without the need for an airlock or depressurizing the spacecraft cabin. Suitports require less mass and volume than airlocks, provide dust mitigation, and prevent cross-contamination of the inside and outside environments. Patents for suitport designs were filed in 1996 by Philip Culbertson Jr. of NASA's Ames Research Center and in 2003 by Joerg Boettcher, Stephen Ransom, and Frank Steinsiek.

Spacesuits in fiction

Further information: Spacesuits in fiction

For as long as there has been fiction set in space, authors have tried to describe or depict the space suits worn by their characters. These fictional suits vary in appearance and technology, and range from the highly authentic to the utterly improbable.

A very early fictional account of space suits can be seen in the book Edison's Conquest of Mars (1898). Later comic book series such as Buck Rogers (1930s) and Dan Dare (1950s) also featured their own takes on space suit design. Science fiction authors such as Robert A. Heinlein contributed to the development of fictional space suit concepts.

See also

Teddy bears lifted to 30,085 metres above sea level on a helium balloon in a materials experiment by CU Spaceflight and SPARKS science club. Each of the bears wore a different space suit designed by 11-13 year olds from SPARKS.

• Pressure Suit
• Sokol space suit
• Orlan space suit
• Space activity suit ("Bio-Suit")
• Extra-vehicular activity
• Manned maneuvering unit
• Human adaptation to space
• List of spacewalks
• List of Mir spacewalks
• List of ISS spacewalks
• List of spacewalks and moonwalks
• List of cumulative spacewalk records

External links

• A Field Guide to American Spacecraft: A list compiled by Lee Sledge and James H. Gerard of American space suits and the museum locations where they are displayed.
• Astronautix.com complete list of Space Suits
• Russian Space Suits
• Design of Soviet/Russian Space Suits
• NASA JSC Oral History Project: See link near page end to Walking to Olympus: An EVA Chronology PDF document.
• NASDA Online Space Notes
• Apollo Extravehicular mobility unit. Volume 1: System description - 1971 (PDF document)
• Apollo Extravehicular mobility unit. Volume 2: Operational procedures - 1971 (PDF document)
• Skylab Extravehicular Activity Development Report - 1974 (PDF document)
• Analysis of the Space Shuttle Extravehicular Mobility Unit - 1986 (PDF document)
• NASA Space Shuttle EVA tools and equipment reference book - 1993 (PDF document)
• Engineering Aspects of Apollo: Section on the Apollo space suit and portable life support system.