Space suit

2007 Schools Wikipedia Selection. Related subjects: Space transport

Space suit from Apollo moonwalk
Space suit from Apollo 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 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 (~63,000ft.), 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.

Spacesuit requirements

Several things are needed for the spacesuit 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.
  • electromagnetic radiation shielding
  • particle radiation shielding
  • micrometeoroid protection
  • mobility
  • a communication system
  • means to recharge and discharge gases and liquids
  • means to maneuver, dock, release, and tether on space craft

Theories of Spacesuit Design

A space suit should allow its user natural and 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 moving an arm or hand causes a change in the volume of the space suit, then the astronaut has to 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.

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 of 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 will cause 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 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 spacesuits 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.

There are three theoretical approaches:

  • 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 joins, and often end up in odd positions that must be manipulated to regain mobility.
  • Mixed suits have hard-shell parts and fabric parts. NASA's Extravehicular Mobility Unit uses a fibreglass 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.
  • Skintight suits, or mechanical counterpressure suits, use a heavy elastic body stocking to compress the body. The head is encompassed 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. See space activity suit for more information.

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".

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.

In May 2006, Fabio Sau, a student at the University of North Dakota, teamed up with forty other students in five North Dakota schools to develop a new spacesuit prototype to demonstrate technologies which could be incorporated into a suit used by astronauts that travel 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 million cost for a 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 differential, NASA's EMU suit operates at a pressure of 4.7 psi. To maintain enough oxygen for respiration, a functional spacesuit using pure oxygen must maintain a minimum pressure of just over 3 psi, equal to the partial pressure of oxygen in the Earth's atmosphere.

Spacesuit models of historical significance

High altitude suits

  • Evgeniy Chertanovskiy created his full-pressure suit or high-altitude skafander in 1931.
  • Wiley Post experimented with a number of hard-shell designs for record-breaking flights

Russian suit models

  • SK-1, the space suit of Yuri Gagarin, the first man in space to orbit Earth
  • Berkut, the space suit of Alexey Leonov, the cosmonaut who made first the spacewalk.
  • the Yastreb space suit for extra-vehicular activity
  • the Orlan suits for extra-vehicular activity
  • the Sokol suits worn by Soyuz crew members during lift-off and re-entry
  • the Strizh space suit developed for pilots of the Buran space shuttle

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

Chinese suit models

  • Shenzhou space suit

Emerging technologies

  • Hard shell
  • Space activity suit
    • MIT's Bio-Suit
  • ILC Dover's I-Suit

Spacesuits in fiction

Fiction authors have been trying to design spacesuits since the beginning of space fiction, as far as there was need to describe them in their stories. Most of them are flexible pressure suits, but usually not as bulky as in real spacesuits. Design was influenced by the real old-type Siebe Gorman Standard diving dress, including sometimes such features as side windows on the helmet.

Edison's Conquest of Mars (written in 1898) says "... yet since it was probable that necessity would arise for occasionally quitting the interior of the electrical ships, Mr. Edison had provided for this emergency by inventing an air-tight dress constructed somewhat after the manner of a diver's suit, but of much lighter material. Each ship was provided with several of these suits, by wearing which one could venture outside the car even when it was beyond the atmosphere of the earth. ...".

In H.G. Wells's The First Men in the Moon (publ. 1901) the Moon has a breathable atmosphere and spacesuits are not needed; the spacecraft has an airtight hatch but no airlock. In the film version made in 1964 the Moon has no atmosphere and no surface vegetation, and standard diving dresses fitted with a big backpack cylinder each are used as spacesuits. However clever an idea for a Victorian spacesuit, the idea is unworkable. First, film director Nathan Juran failed to provide a pressurized atmosphere inside the diving suit of his 1899 astronauts (he also forgot any kind of glove). Second, the rubberized material of a diving suit would have crumbled upon contact to the cold and vacuum of space; the volatiles in the rubberized material would have been lost immediately upon space exposure.

Many fictional spacesuits have two big backpack cylinders as their only life-support gear, as if the wearer breathes out to space like in ordinary sport open-circuit scuba. In the well-known Dan Dare series which started in April 1950 in the `Eagle' comic, the usual Spacefleet spacesuit has no backpack, and a corselet like in Standard Diving Dress. Comic-strip space story authors often do not know about the effects of internal pressure inflating the spacesuit in space, but draw the spacesuit in space hanging in folds like a boilersuit: that can often be seen in the Dan Dare stories.

Skintight spacesuits ( skinsuits) appear in the original Buck Rogers comics. The Buck Rogers scenario has become familiar enough to cause expressions such as "Buck Rogers outfit" for real protective suits that look somewhat like spacesuits. Skinsuits are more common in modern science fiction. On the other end of the spectrum one can find the ideas of heavy powered armor. Robert A. Heinlein's novel Have Space Suit-Will Travel draws on his experience designing pressure suits during World War II.

It is possible that fictional spacesuit design influenced real spacesuit design somewhat, at least in getting real spacesuits to use a hard helmet and not a soft pressurized hood.

Alien spacesuits in the Gerry Anderson UFO series are filled with a breathable liquid to resist acceleration stresses.

After NASA started, fictional spacesuits often followed real spacesuit design, in such features as having a large rectangular backpack. In making the spacesuits that are seen in the Dune movie, the prop and costume designers stated a need to avoid "that NASA look", and the same consideration may have arisen in some other movies and series.

Spacesuits are commonly used in the Gundam anime metaseries, but are often renamed to avoid confusion with space-use mobile suits. In the Universal Century timeline, spacesuits are called "normal suits"; the After Colony timeline calls them "astrosuit". Gundam spacesuits often have a pouch full of adhesive strips, used to temporarily seal tears in the suit or cracks in the helmet (as demonstrated in Mobile Suit Gundam and Char's Counterattack respectively).

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