Suiting up
The EMU comprises the spacesuit assembly, the primary life support system (PLSS), the display and control module, and several other crew items designed
for spacewalks and emergency life support. The EMU accommodates a variety of interchangeable systems that interconnect easily and securely in single-handed
operation for either normal or emergency use. When preparing to work in space, the astronaut goes into the airlock of the space shuttle orbiter and puts
on the following parts of the EMU:
• A urine-collection device that receives and stores urine for transfer later to the orbiter waste management system.
• A liquid cooling and ventilation garment, a one-piece mesh suit made of spandex, zippered for front entry, and weighing 6.5 pounds dry. The garment has
water-cooling tubes running through it to keep the wearer comfortable during active work periods.
• An in-suit drink bag containing 21 ounces of potable water, the "Snoopy Cap," or communications carrier assembly, with headphones and microphones for
two-way communications and caution-and-warning tones, and a biomedical instrumentation subsystem.
To put on the spacesuit, the astronaut first dons the lower torso assembly and then rises into the top section of the two-piece EMU spacesuit hanging on the
wall of the airlock. The upper torso of the spacesuit is a hard-shell fiberglass structure that contains the primary life support system and the display control
module. Connections between the two parts must be aligned to enable circulation of water and gas into the liquid cooling ventilation garment and return. Then,
the gloves are added and last to be donned is the extravehicular visor and helmet assembly, which provides protection from micrometeoroids and from solar
ultraviolet and infrared radiation. Bearings in the shoulder, arm, wrist, and waist joints allow the crewmember freedom of movement. Bending, leaning, and
twisting motions of the torso can all be done with relative ease.