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The space suit: a mini-spacecraft

The suit that protects astronauts when they perform a spacewalk is one of the most complex and important pieces of equipment they use.

It is, in fact, a mini spacecraft in itself, providing the essentials of life needed to keep astronauts alive and safe while working outside.

Officially known as the Extravehicular Mobility Unit or EMU, the suit has two main components: the Space Suit Assembly (SSA) and the Primary Life Support System (PLSS).

The SSA includes:

• urine collection device: collects body wastes, which are later transferred to the Shuttle’s waste management system.
  
  
• bioinstrumentation system: monitors the astronaut’s heart rate during spacewalks.
  
  
• liquid cooling and ventilation garment: a "long-john" made of spandex, containing 90 metres of small tubes that circulate cooling water over the body.
  
  
• communications carrier assembly: a "Snoopy" cap containing headphones and microphones for two-way communications. Newer models allow up to five people to talk together.
  
  
• lower torso assembly: the pants and attached boots, comprised of several layers of fabric that protect the astronaut from extreme temperatures and micrometeroids. The outer layer has three anti-abrasion materials, including Kevlar, the fabric that bullet-proof vests are made of.
  
  
• hard upper torso (HUT): the top half of the suit, made of fibreglass, which supports the Primary Life Support System.
  
  
• gloves: the heavy gloves have rubber tips to increase dexterity. Newer models have fingertip heaters to keep the hands warm.
  
  
• helmet and visor assembly: the helmet and adjustable visor protect the head and eyes from direct sunlight, ultraviolet and infrared radiation and micrometeroids. It’s mounted with headlamps to illuminate the work area when astronauts work in darkness.
  
  

The suit components come in several sizes and can be adjusted to fit men and women ranging from 5 to 95 percent of body sizes. The HUT comes in four sizes, while the pants have six waist sizes. There are two boot sizes, but can be adjusted with slipper inserts that come in six sizes. The gloves come in nine sizes and are the most customizable parts of the suit.

The Shuttle suits have been adapted for use on the Space Station. Rather than being returned to Earth for cleaning and repair after each mission, the Station suits will be stored on the Station for up to 25 spacewalks and will be cleaned and maintained on orbit.