Science Fair Project Encyclopedia
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.
In order to function properly in the environment of space, there are several requirements which must be fulfilled to achieve proper system operation. A spacesuit must provide:
- Internal pressure stabilization. This can be less than earth's atmosphere, as there is usually no need for the spacesuit to carry nitrogen.
- A breathing set. In all independent real spacesuits this is a rebreather, which recycles the exhaled gas.
- Temperature regulation, specifically cooling. Space is very cold, but there is no matter in space to carry heat away from the astronaut, so he can only lose heat by radiating heat; also, the astronaut will likely be warmed by sunlight.
- Radiation shielding.
- Ability to make normal body joint movements
- A two-way radio for communication.
- 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.
An example of this challenge can be understood by imagining the task of bending an arm inside a straight, pressurized sleeve. The arm is inside a gas-filled tube, largely identical in dynamics to the long balloons used in balloon modelling. If such a tube is caused to fold at some point along its length, air is forced out of the fold into the rest of the balloon, increasing pressure. Unless this pressure is released somehow, the resulting force will tend to return the tube (balloon or spacesuit) to its 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.
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.
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".
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.
- Skintight 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.
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.
Spacesuit models of historical significance
- High altitude suits
- Wiley Post experimented with a number of hard-shell designs for record-breaking flights
- Russian suit models
- Mercury high-altitude/vacuum suit
- Gemini spacewalk suits
- Apollo lunar surface suits
- Space Shuttle
- Emerging technologies
- Hard shell
- Space activity 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. In H.G. Wells's The First men in the Moon (publ. 1901) Standard Diving Dresses are fitted with a big backpack cylinder each and used as spacesuits. 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.
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.
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.
After NASA started, fictional spacesuits often followed real spacesuit design, in such features as having a large rectangular backpack.
- 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)
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