Space suit

From Wikipedia, the free encyclopedia

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 (~63,000 ft/~19,000 m), pressurized suits are needed in the sparse atmosphere. Hazmat suits that resemble space suits are also used when dealing with certain types of biological hazards.

Contents 1 Spacesuit requirements 2 Theories of spacesuit design 2.1 Hard-shell suits 2.2 Mixed suits 2.3 Skintight suits 3 Contributing technologies 4 Spacesuit models of historical significance 4.1 High altitude suits 4.2 Russian suit models 4.3 American suit models 4.4 Chinese suit models 5 Emerging technologies 5.1 Mark III 5.2 I-Suit 5.3 Bio-Suit 5.4 North Dakota suit 5.5 NASA Constellation Space Suit System 6 Spacesuits in fiction 7 See also 8 References 9 External links

[edit] Spacesuit requirements

Several things are needed for the space suit to function properly in space. 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. Lower pressure allows for greater mobility, but introduces the requirement of pre-breathing to avoid decompression sickness.
• Breathable oxygen. Circulation of cooled and purified oxygen is controlled by the Primary Life Support System.
• Temperature regulation. Heat can only be lost in space by thermal radiation, or conduction with objects in physical contact with the space suit. Since heat is lost very slowly by radiation, temperature is regulated by a Liquid Cooling Garment and heavy insulation on the hands and possibly feet.
• Shielding against harmful electromagnetic radiation
• Shielding against particle radiation
• Protection against micrometeoroids, provided by a Thermal Micrometeoroid Garment, which is the outermost layer of the suit
• Mobility
• A communication system
• Means to recharge and discharge gases and liquids
• Means to maneuver, dock, release, and tether on space craft

[edit] 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 changes 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 your suit. It also makes delicate movements very difficult. The work required to bend a joint is dictated by the formula

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. Because pressure is dictated by life support requirements, the only means of 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. This makes up for the volume lost on the inside of the joint, and keeps the suit at a nearly constant volume. However, once the gores are opened all the way, the joint cannot be bent anymore without a considerable amount of work.

In some Russian space suits, strips of cloth were wrapped tightly round the spaceman'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:

[edit] 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.

[edit] 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 is the waist seal, bearings, and in the case of rear-entry suits, the back hatch, where all-soft alternatives are not viable.

[edit] 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, and reduces the possibility of a space suit depressurization. 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.

[edit] 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".

[edit] Spacesuit models of historical significance

[edit] High altitude suits

• Evgeniy Chertanovskiy 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.

[edit] Russian suit models

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

SK-1 space suit

Krechet space suit

Orlan space suit

Sokol space suit

[edit] American suit models

• Mercury high-altitude/vacuum suit
• Gemini spacewalk suits
• MOL space suits
• Apollo and Skylab EVA and moon suits
• Advance Crew Escape System Pressure Suit on the Space Shuttle
• Shuttle/ISS EMU on both the Space Shuttle and International Space Station

Mercury vacuum suit	Gemini spacewalk suits	MOL space suit	Apollo and Skylab EVA and moon suits
Advance Crew Escape System Pressure Suit	Shuttle/ISS EMU

[edit] Chinese suit models

• Shenzhou space suit

The suit worn by taikonaut 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. 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.

Shenzhou 5 space suit

Shenzhou 6 space suit

[edit] Emerging technologies

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

[edit] 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 (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 health risks such as the bends which can occur with rapid depressurization from an atmosphere containing Nitrogen.

[edit] 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.

[edit] Bio-Suit

The Bio-Suit is a space activity suit under development at MIT, which as of 2006 consists of several lower leg prototypes.

[edit] North Dakota suit

Starting in May 2006, 41 students from five North Dakota schools, including the University of North Dakota, developed a new spacesuit prototype to demonstrate technologies which could be incorporated into a suit used by astronauts travelling to Mars. The students worked off of a $100,000 grant by NASA, and the suit was tested in the Theodore Roosevelt National Park Badlands of western North Dakota. The suit weighs 47 pounds without a life support backpack, and costs only a fraction of the standard $22,000,000 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.^[1]

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 differential, NASA's EMU suit operates at a pressure of 4.7 psi. Generally, to supply enough oxygen for respiration, a spacesuit using pure oxygen must have a minimum pressure of 3 psi, equal to the partial pressure of oxygen in the Earth's atmosphere at sea level.

[edit] 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 a space suit system to meet the needs of Project Constellation.^[2] NASA forsees a single suit capable of supporting: survivability during launch, entry and abort; zero-gravity EVA; lunar surface EVA; and Mars surface EVA.

[edit] Spacesuits in fiction

Fiction authors have been trying to design space suits since the beginning of space fiction, as far as there was need to describe them in their stories. Most of them were essentially flexible pressure suits, but usually not as bulky as real spacesuits.

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.

[edit] See also

• Manned maneuvering unit
• Space activity suit
• Human adaptation to space

[edit] References

1. ^ http://www.signonsandiego.com/uniontrib/20060507/news_1n7suit.html
2. ^ http://prod.nais.nasa.gov/cgi-bin/eps/synopsis.cgi?acqid=121486

[edit] 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.

v • d • e Space suits
American models	Navy Mark V • Gemini Space suit • MOL Space suit • Apollo/Skylab A7L • Extravehicular Mobility Unit • Advanced Crew Escape Suit
Russian models	SK-1 • Yastreb • Krechet • Sokol • Orlan • Strizh
Developing technologies	Mark III • I-Suit • Bio-Suit • Space activity suit
Components	Hard Upper Torso • Liquid Cooling and Ventilation Garment • Primary Life Support System • Thermal Micrometeoroid Garment
Related topics	Extra-vehicular activity • Manned Maneuvering Unit • Pressure suit