The Space Shuttle Extravehicular Mobility Unit (EMU)
As NASA changed from launching astronauts on expendable rockets
to the Space Shuttle system with its reusable orbiter and solid
rocket boosters, spacesuit engineers began development of a reusable
EMU. Previously, all spacesuits were one-time garments. Spacesuits
were custom-built to each astronauts body size. In the Apollo
program, for example, each astronaut had three custom suits- one
for flight, one for training, and one for flight backup. Shuttle
suits, however, are tailored from a stock of standard-size parts
to fit astronauts with a wide range of measurements.
In constructing the Shuttle spacesuit, designers were able to concentrate
all their designs toward a single function- going EVA. Suits from
earlier manned spaceflight programs had to serve multiple functions.
They had to provide backup pressure in case of cabin pressure failure
and, on Gemini missions, protection if ejection became necessary
during launch. They also had to provide an environment for EVA in
microgravity and in low gravity while walking on the Moon (Apollo
missions). Suits were worn during lift off and reentry and had to
be comfortable under the high-g forces experienced during acceleration
and deceleration. Shuttle suits are worn only when it is time to
venture outside the orbiter cabin. At other times, crew members
wear comfortable shirts and slacks, or shorts. For launch and reentry,
special orange-colored flight suits with helmets are worn.