For most of us, spacesuits are mysterious, wondrous devices. Utilizing little more than some bulky fabric, complex looking equipment and a visor, these suits allow human beings to exist safely in the vacuum of space - an environment where humans cannot normally survive for long. How is this possible?
Spacesuits are, in essence, self-contained shells that allow the astronaut to operate independently of their ship or space station for limited periods of time. Because space is a dangerous environment for an exposed human, spacesuits must fulfill a battery of requirements, and include the following components:
- A stable internal pressure, much like that for workers at great depths underwater. This pressure is typically kept low, allowing the astronaut to operate more quickly in space;
- A system for the delivery of oxygen and the removal of carbon dioxide, the primary factor for the limited nature of time in a spacesuit;
- A comfortable environment, neither too hot nor too cold, as space is both wickedly cold but also does not reflect the sun's rays away from the astronaut;
- Protection from micrometeoroids that may stray too close via puncture-resistant materials;
- A communications system for relaying and receiving messages with other astronauts and ground control;
- Mechanisms for tethering to spacecraft and/or space stations; and
- The ability to both maneuver safely and see properly.
In short, a spacesuit must effectively recreate Earth-like conditions in which a human can survive comfortably. All this makes the average spacesuit a fiendishly complex creation, one with thousands of parts that can prove surprisingly fragile - yet they must remain tough, for any of these systems failing can, in the high-danger region of space, prove disastrous to an astronaut.
Typically, spacesuits come complete with tethers that allow them to remain safely fixed to a space station or shuttle. These tethers also provide a steady flow of oxygen to the astronaut. Before going out into space, the astronaut is prepared by breathing pure oxygen for a period of time - Earth's normal air contains insufficient amounts of oxygen to keep astronauts from passing out - which will continue to be filtered through the suit during a space walk. The carbon dioxide generated by inhalation and exhalation is filtered out of the suit's atmosphere via carbon dioxide scrubbers before it can rise to lethal levels.
While working in space, astronauts are subjected to zero gravity and the problems of movement in an inflated suit, both of which make maneuvering and working difficult. Flexing an arm is difficult, and slight motions can send astronauts flying in the wrong direction since they are not rooted down by gravity. To compensate for these problems spacecraft are peppered with restraints and footholds to help astronauts work, and their suits have extra joints to aid in unobstructed arm and leg movement. Astronauts are also thoroughly trained on Earth in underwater conditions, which closely simulate zero gravity, to acclimate to the feeling of weightlessness that comes with wearing a spacesuit.
Protection, as noted above, is of great importance to a spacesuit, as radiation moves freely in space and the severe temperature can quickly get to an astronaut. To compensate for these problems spacesuits are typically coated in Mylar and come equipped with environmental systems that keep the astronaut at a stable temperature throughout the space walk. Most such forays into space are also planned for times of low solar activity that can prove disastrous for an exposed astronaut. Spacesuits can only protect against so much.
In order to understand just how a spacesuit works, however, it's best to watch them in action. Keep what you've read in mind and check out NASA's website, which contains many videos of astronauts working in their spacesuits. Keep in mind, too, what would happen to a person were they left out in the vacuum without a spacesuit, and you'll quickly realize just how important advanced spacesuit technology is to astronauts - not to mention how impressive these spacesuits are in practice.