Spacesuit

A spacesuit 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.

Spacesuit requirements

In order to function properly in the environment of space, there are several requirements which must be fulfilled to achieve proper system operation. A suit must provide:

• internal pressure stabalization (like the air pressure on Earth),
• breathing gas storage
• breathable gas mixture regulation (to balance oxygen, hydrogen, nitrogen, etc,.. for conditions)
• Exhaled gas storage or recycling
• temperature regulation, specifically cooling: While space is very cold, there's nowhere for the heat from the astronaut to go; also, the astronaut will likely be warmed by sunlight.
• radiation shielding.
• appropriate wear surfaces for use (shoes, knee pads, etc.)
• appropriate mount interfaces for loading and unloading gases and liquids.
• appropriate system mounts for maneuvering with space craft, through environmental locks, docking, releasing, tethering to system modules.

Theories of spacesuit design

Added to these requirements, each technically solvable, is the requirement for the spacesuit to be movable, and allow the user some degree of freedom of motion. This is actually one of the most difficult parts of spacesuit design.

Think of an movable part of the suit, for instance, an arm, when the arm is bent from an original position straight out. The arm is inside a gas-filled tube, largely identical in dynamics to the long balloons use to make balloon animals for children. If you attempt this same manuver with such a balloon you'll find it is actually difficult: the balloon will fold at some point along its length, which forces air out of the fold into the rest of the balloon, increasing pressure. If you release the force, the balloon, or spacesuit, will return to it's original unbent state.

This constant action against the user's motion can be seriously fatiguing, and make delicate control almost impossible. Current solutions focus on using bellows-like folds, the folds grow larger on the outside of the bend while the inside grows smaller, equalizing pressure. However these have a limited amount of motion, once the outside folds are all the way open, they cannot move any further. Such a system can be seen in the Apollo suit in the picture above, the diamond shapes in the fabric over the right elbow are caused by the bellows under it.

The goal of spacesuit design, then, is to provide all the needed requirements in a suit that is also highly mobile. Today's suit designs fail in this goal, although they are improving. More "radical" design concepts have been proposed.

There are three theoretical approaches:

• Flexible pressure suits are the kind most in use. They combine all the bad features: heavy weight, the need for a cool suit, and difficult motion because the suit wants to blow up like a balloon. Their one saving grace is that they do not limit the range of motion.
• Hard-shell suits have constant volumes, and motion is therefore very easy, because the pressure inside the suit does not oppose motion. Instead of air conditioning, most hard suits use a cool-suit with soft tubes carrying water, which is then evaporated into the vacuum for cooling. 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 in order to regain mobility.
• Skin suits use a heavy body stocking to compress the body, as opposed to pressurizing it with air. Most proposals use the body's natural sweat to keep cool. See space activity suit for more information.

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.

Specific suit models of historical significance

• High altitude suits
  • Wiley Post experimented with a number of hard-shell designs for record-breaking flights
• Russian suit models
  • Yuri Gagarin, first man in space orbits Earth
  • the Orlan suits for extra-vehicular activity
  • the Sokol suits worn by Soyuz crew members during lift-off and re-entry
• Mercury high-altitude/vacuum suit
• Gemini spacewalk suits
• Apollo lunar surface suits
• Skylab
• Space Shuttle
• Emerging technologies
  • Hard shell
  • Space activity suit

See also

• Manned maneuvering unit
• Space activity suit

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"Space Suit" is an instrumental track from They Might Be Giants' 1992 album Apollo 18.