The Spacesuit - A Primer on Spacesuits

During orbit, astronauts work inside the space shuttle in shirt-sleeve comfort. Prior to a mission, crew members are outfitted from a selection of clothing including flight suits, trousers, lined zipper jackets, knit shirts, sleep shorts, soft slippers, and underwear. The materials of every component of the clothing are flame retardant. Covering the exterior of the garments are close-able pockets for storing such items as pens, pencils, data books, sunglasses, a multipurpose Swiss army pocketknife, and scissors.

Working Outside the Space Shuttle

To work in the open cargo bay of the space shuttle or in space, astronauts wear the shuttle extravehicular mobility unit (EMU) spacesuit, which was developed to be more durable and more flexible than previous spacesuits were. The suit is modular in design, with many interchangeable parts. The upper torso, lower torso, arms, and gloves are manufactured in different sizes and can be assembled for each mission in combinations needed to fit men and women astronauts. This design is cost-effective because the suits are reusable and not custom fitted as were spacesuits used in previous NASA manned space flight programs.

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.

All fabric-to-hardware connections are made with either mechanical joints or adhesive bonding. Materials used in the construction of the suit are selected to prevent fungus or bacteria growth; however, the suit must be cleaned and dried after flight use.

The entire suit assembly is rated with a minimum 8-year life expectancy. The nominal operating atmospheric pressure in the suit is 4.3 psid. The suit comprises several layers including a polyurethane-coated nylon pressure bladder, a polyester structural restraint layer with folded and pleated joints (for mobility), and a woven Kevlar, Teflon, and Dacron anti-abrasion outer layer.

The maximum total weight of the largest size spacesuit assembly, including the liquid cooling and ventilation garment, urine collection device, helmet and visor assembly, communications carrier assembly, insuit drink bag, and biomedical instrumentation subsystem, is 107 pounds.

The astronaut is ready to go to work in space and secures the necessary tools to the mini-workstation of the suit. The EMU lights are mounted on the helmet and are a necessity because during orbital operations approximately every other 45 minutes are spent in darkness.