| Spacesuits
are designed to protect astronauts from the many dangers in
space. When an astronaut steps outside the spacecraft,
there is little or no atmosphere. Therefore, spacesuits
must have a pressurized atmosphere, giving the astronaut
oxygen and removing the carbon monoxide.
The spacesuit
provides air pressure keeping the body in a liquid
state. Without the air pressure the astronaut's blood
and body fluid would "boil" and then freeze.
Spacesuits
cannot use normal air. The low pressure would cause low oxygen
concentrations in the lungs and blood. Therefore, most
suits provide a pure oxygen atmosphere for breathing.
The oxygen will come from either from a spacecraft via an
umbilical cord or a backpack life support system.
Since the space
suit is a confined space, the carbon dioxide that the
astronaut breathes out would build to deadly levels.
Therefore, excess carbon dioxide must be removed from the
atmosphere. Spacesuits use lithium hydroxide canisters
to remove the carbon dioxide. These are located in the
the suit's life support backpack or within the
spacecraft.
The astronaut
will face drastic changes in temperature such as 248 degrees
fahrenheit to -148 degrees fahrenheit, therefore, the
suit must be designed to maintain a comfortable
and safe temperature .
Most spacesuits
are heavily insulted with layers of fabric and covered with
reflective outer layers (mylar) to reflect the sunlight. The
astronaut does many strenuous activities producing heat.
If the heat is not removed, the sweat will fog up the helmut
and cause the astronaut to become severely dehydrated.
Therefore, spacesuits must have either fans or heat exchangers
to blow cool air, or water-cooled garments.
In order
to protect the astronaut from micrometeoroids or
orbiting debris, the spacesuits have multiple layers of
durable fabrics such as Dacron or Kevlar. These layers
prevent the suit from tearing on exposed surfaces.
In
addition to extreme temperatures, the astronaut must be
protected from various types of radiation, cosmic rays and
solar wind. Spacesuits offer limited protection with
reflective coatings of Mylar which are built into the
suits. Since the spacesuit does not provide much
protection from a solar flare, spacewalks are planned during
periods of low solar activity.
While the
spacesuit must protect the astronaut from all these potential
dangers, it must also be designed so that the astronaut can
see clearly, can move easily inside the spacesuit, allow
movement around the outside of the spacecraft and allow
the astronaut to talk with others.
Spacesuits have
helmets made of clear plastic or durable polycarbonate.
Most have coverings that reflect sunlight, and tinted visors
to reduce glare. The inside faceplates of the helmet are
sprayed with an anti-fog compound before an astronaut begins a
spacewalk. Modern helmets coverings include mounted
lights enabling the astronaut to see into the shadows.
Spacesuits are
equipped with special joints or tapers in the fabric which
help the astronauts bend their hands, arms, legs, knees, and
ankles.
The astronauts
communicate with ground controllers and other astronauts with
transmitters/receivers that are located in the chestpacks and
backpacks that they wear. The astronauts wear headsets
with microphones and earphones.
Space suits
have undergone many changes over the years.
Project Mercury
- became an official NASA program on October 7, 1958. (Photo)
"spacesuits were a modified version of a U.S. Navy high
altitude jet, aircraft pressure unit. The design was
made of two layers. The first layer retained pure
oxygen, consisted of an inner gas-bladder layer of
neoprene-coated fabric and an outer restraint layer of
aluminized nylon; the second layer prevented the first from
expanding like a balloon. Mobility was limited to the
arms and legs with simple fabric break lines sewn into the
suit."
(The
Official Souvenir Book of Space
Center Houston 2001)
Project Gemini
- the 10-flight Gemini program began in April 8, 1964. (Photo)
"life-giving oxygen was fed to the spacesuit by a 25-foot
umbilical cord to a chest-mounted pressure regulator and
ventilation assembly. Improvements to the suit allowed
greater mobility in the shoulders and arms. The pressure
bladder was made of Neoprene-coated nylon and covered by a
load-bearing link-net woven from Dacron and Teflon
cords. The net layer, being slightly smaller than the
pressure bladder; reduced the stiffness of the suit when
pressurized and served as a sort of structural shell, like an
innertube.
(The
Official Souvenir Book of Space
Center Houston 2001)
Project Apollo-
(Photos)
"Apollo suits had to serve as a backup pressure system to
the space capsule and give more mobility to the
astronaut. Besides allowing flexibility in the shoulder
and arm areas, they also had to permit movements of the legs
and waist. Astronauts needed to bend to stoop to pick up
samples on the Moon. A self-contained portable
life-support system was created for the "moon
walk." The rechargeable backpack unit provided
oxygen for breathing and pressurization, water for cooling and
radio communications for lunar surface excursions lasting up
to eight hours. Apollo space helmets were fixed into
place on the spacesuit, freeing the astronaut to move his head
within the helmet. The lunar boot was made from
metal-woven fabric with a silicone rubber sole. Lunar
surface gloves had special thumb and fingerprints molded of
silicone rubber to permit a degree of sensitivity and
"feel."
(The
Official Souvenir Book of Space
Center Houston 2001)
Space Shuttle
"Astronauts of today's Space Shuttle era have more than
one wardrobe for space flight. What they wear depends on the
job they are doing.
During ascent
and entry, each crew member wears special equipment consisting
of a partial-pressure suit, a parachute harness assembly and a
parachute pack. The partial pressure suit consisting of
a helmet, communication assembly torso, gloves and boots,
provides counter-pressure and anti-exposure functions in an
emergency situation in which the crew must parachute form the
orbiter. The suit has inflatable bladders that fill it
with oxygen from the orbiter. These bladders inflate
automatically at reduced cabin pressure. They can also
be manually inflated during entry to prevent the crew member
from blacking out. Without the suit pressing on the
abdomen and the legs, the blood would pool in the lower part
of the body and cause a person to black out as the spacecraft
returns from microgravity to Earth's gravity."
(The
Official Souvenir Book of Space
Center Houston 2001)
The Extravehicular
Mobility Unit
To work in
the open cargo by of today's 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. 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 to each astronaut as were spacesuits
used in previous NASA manned space flight programs.
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 in-suit drink bag, and biomedical instrumentation
subsystem, is 107 pounds.
1.
How
Spacesuits Work, by Craig
C. Freudenrich,
Ph.D.
http://www.howstuffworks.com/space-suit1.htm
2.
The Official Souvenir
Book of Space Center Houston
2001
|
