The Complete Book of Spaceflight: From Apollo 1 to Zero Gravity

spacesuit Daniel Barry, STS-96 mission specialist, wears a training version of the extravehicular mobility unit spacesuit
during an underwater simulation of a spacewalk planned for an early Internal Space Station mission. NASA
Gemini helmets, which were closely fitted and moved
with the crewman’s head, the Apollo helmet was fixed
and the head free to move within. While walking on
the Moon, Apollo crewmen wore an outer, goldcoated
visor to shield against ultraviolet radiation and
help keep the head and face cool. Completing the
Apollo astronaut’s ensemble were lunar gloves and
boots, both designed for the rigors of exploring, and
the gloves for adjusting sensitive instruments. Modified
Apollo suits were also used on the Skylab missions
and the Apollo-Soyuz Test Project.
Shuttle and ISS Garb
During ascent to and descent from orbit, Shuttle
astronauts wear special orange partial pressure suits
with helmet, gloves, and boots in case of a loss of
cabin pressure. Once in orbit, crew members inside
the Shuttle enjoy shirtsleeve comfort. To work in the
Shuttle’s open cargo bay or perform other tasks outside
the spacecraft, they don spacesuits known as
extravehicular mobility units (EMUs), more durable
and flexible than any previous suits. The EMU is
modular, enabling it to be built up from a number of
parts depending on the particular task in hand. Also,
the upper torso, lower torso, arms, and gloves are not
individually tailored but made in a variety of sizes
that can be put together in combinations to fit crew
members of any size, man or woman. Each suit has
supplies for a 6.5-hour spacewalk plus a 30-minute
reserve and is pressurized to just under one third of
atmospheric pressure. Before donning the suit, astronauts
spend several hours breathing pure oxygen
because the suit also uses 100% oxygen, whereas the
habitable decks on the Shuttle use an Earth-normal
21% oxygen/79% nitrogen mixture at atmospheric
pressure (reduced to 0.69 atmosphere before an EVA).
This preparation is necessary to remove the nitrogen
dissolved in body fluids to prevent its release as gas
bubbles when pressure is reduced, a condition commonly
called the bends.
The following parts of the EMU go on first: a
urine-collection device, a liquid-cooled undergarment
plumbed with 100 m of plastic tubing through which
water circulates, an in-suit drink bag containing
600 grams of potable water, a communications system
(known as the Snoopy Cap) with headphones
and microphones, and a biomedical instrumentation
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