How does a spacesuit work?

This should be entitled: how does a spacesuit protect an astronaut in space?

We've seen spacesuits in real situations such as when the Apollo astronauts walked on the moon, or when the ISS (International Space Station) astronauts go out for an EVA or extra vehicular activity.

A space suit has the functionality to protect a human in space. This is a tall order because space is hostile. First of all it's a vacuum, and to make things worse it's very cold, or it can be very hot. The space suit must supply an artificial atmosphere and be able to both cool and heat the human inside, depending upon the conditions. The astronaut will be cold if in a shadow and hot if directly in sunlight. In other words the suit must provide good temperature regulation.

The astronaut needs oxygen at a pressure consistent with breathing. Most suits supply oxygen at a lower pressure, but the astronaut must breath pure oxygen for a period of time before going to this lower pressure to avoid the bends, better known as decompression sickness. This sickness results because the nitrogen in a human's blood bubbles out at lower pressure to cause all sorts of tissue damage. Breathing pure oxygen and exercising will prevent this, but it runs the risk of fire. Remember what happened to the astronauts in the Apollo-1 disaster. A spark caused the capsule, pressurized with pure oxygen, to burn, killing them.

The other important spacesuit function is that while keeping the astronaut alive it has to allow for mobility. This makes it even more difficult to make a suit that does all of these life-saving functions, but the astronaut has to have some mobility in order to do work in outer space.

There are also other needs. A communication system is needed so that the astronaut can keep in contact with mission control or the spacecraft. The suit also needs a bodily fluid and solid waste containing system. There are no bathrooms in outer space.

What's really wild is that some spacesuits are made mostly from fabrics. They allow the most mobility. NASA uses suits that are a combination of hard materials like metals and plastics and fabrics. In many cases the joints are on bearings and look like robot appendages. One advantage of a hard suit is it can use higher pressures, alleviating the problem of pre-breathing oxygen.

The ideal spacesuit would be a skintight one, something that resembles a divers wet suit. This would eliminate a lot of the pressurization problems because only the helmet would have an atmosphere. I like this idea especially for Mars exploration, but it's still in the design phase. The ideal suit would also have some way to protect an astronaut from not only micro meteor hits (this is the case with current hard suits) but also protect him or her from radiation. This is not easy because strong radiation in space can penetrate most everything.

With current technology, each suit must be carefully fitted to the astronaut that will wear it. All of this is expensive. Just consider how the spacesuit gloves had to be made in order for the astronaut to do work in space. They are a marvel of both material technology and smart design.

Thanks for reading.