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No one could survive in space for more than a minute without an astronaut suit. Beyond being a complex set of garments, what exactly does a space suit do and how does it protect the wearer?
There are several goals that an astronaut suit has to meet/provide:
First, is 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 has the down side that the wearer has to breathe pure oxygen for a time before wearing it to avoid decompression sickness.
The suit has to allow ease of motion. Movement is typically limited by the suit’s pressure, but mobility is achieved by joint design.
The astronaut has to have access to breathable oxygen at all times…this is provided by the primary life support system(PLSS).
Along with oxygen, temperature control is extremely important. In space heat is lost only by thermal radiation or conduction by physical contact. Temperatures on the outside of the suit vary greatly between sunlight and shadow, so the suit is heavily insulated. The internal temperature is regulated by the liquid cooling garment that is in contact with the astronaut’s skin and the air temperature maintained by the PLSS.
The suit must also protect the astronaut from dangers inherent to space: ultraviolet radiation, particle radiation, and micrometeorites.
Other features include a method to recharge and exchange gases and liquids, communications, a way to tether to a spacecraft, and a means to collect and contain human wastes.
An astronaut suit is essential for extravehicular activity. Each suit has 18,000 and it contains everything an astronaut needs to stay alive. For example, the suits used on Apollo/Skylab missions included eleven layers in all: an inner liner, a liquid cooling and ventilation garment, a pressure bladder, a restraint layer, another liner, a thermal micrometeoroid garment consisting of five aluminum coated insulation layers, and an external layer of white Ortho-Fabric. These spacesuits are capable of protecting an astronaut from temperatures ranging from -156 °C to +121 °C.