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Homework Help: Science: Outer Space: Space Suits
by Melanie Madeira
Introduction
To explore and work in space, humans have to take their environment with
them because there is no atmospheric pressure and no oxygen to sustain
life. Inside the spacecraft, the atmosphere can be controlled so that
special clothing isn?t needed, but when outside, humans need the protection
of a spacesuit.
The Job of a Space Suit
Outer space is an extremely dangerous place. If you were to step outside
a spacecraft such as the International Space Station, or onto a world with
little or no atmosphere, such as the moon or Mars, and you were not wearing
a spacesuit, you would be in a very deadly situation. An astronaut would
become unconscious within fifteen seconds because there is no oxygen. Most
spacesuits provide a pure oxygen atmosphere for breathing. Spacesuits get
the oxygen either from a spacecraft or from a backpack life support system
that the astronaut wears. Your blood and body fluids would boil and then
freeze because there is little or no air pressure. The cabin pressure of
either the shuttle itself or an airlock must be reduced before an astronaut
gets suited up for a space walk. A space walking astronaut runs the risk
of getting the bends because of the changes in pressure between the
spacesuit and the shuttle cabin. The bends is when your lungs contract in
size by a factor of two. There is twice as much pressure around the air in
your lungs. You would be exposed to various types of radiation, such as
cosmic rays and charged particles from the sun. Spacesuits do not offer a
lot of protection for radiation, but the reflective coatings of Mylar that
are built into the suits offer some protection. You could also be hit by
small particles of micrometeoroids. A micrometeoroid is a very small,
often dust-sized meteoroid. Space suits have many layers of durable
fabrics called Dacron or Kevlar. These layers also prevent the suit from
tearing on exposed surfaces of the spacecraft or a planet or moon. They
give you oxygen and remove carbon dioxide. The astronaut breathes out
carbon dioxide. In the small space of the suit, carbon dioxide
concentrations would build up to deadly levels. Therefore, excess carbon
dioxide must be removed from the spacesuit's atmosphere. Spacesuits use
lithium hydroxide canisters to remove carbon dioxide. These canisters are
located either in the spacesuit's life support backpack or in the
spacecraft, which are accessed through an umbilical cord. The space suits
keep comfortable temperatures. Spacesuits are heavily insulated with layers
that are called Neoprene, Gore-Tex, and Dacron. They are covered with
reflective outer layers called Mylar to reflect sunlight. The astronaut
produces heat from their body, especially when doing strenuous activities.
If this heat is not removed, the sweat produced by the astronaut will fog
up the helmet and cause the astronaut to become severely dehydrated. To
remove this extra heat, spacesuits have used either heat exchangers to blow
cool air or water-cooled garments The space suit lets you see clearly.
Spacesuits have helmets that are made of clear plastic or durable
polycarbonate. Most helmets have coverings to reflect sunlight and tinted
visors to reduce glare. Before the space walk, the helmets are sprayed with
an anti-fog compound. These helmets also have mounted lights so the
astronauts can see into the shadows. The space suit lets you talk with
ground controllers and other astronauts Spacesuits are equipped with radio
transmitters and receivers so that space walking astronauts can talk with
ground controllers and other astronauts. The astronauts wear headsets with
microphones and earphones. The transmitters and receivers are located in
the chest packs and backpacks worn by the astronauts. And last but not
least, the space suits let you move around the outside of the spacecraft.
Moving within an inflated spacesuit is tough, so to help this problem,
spacesuits are equipped with special joints or tapers in the fabric to help
the astronauts bend their hands, arms, legs, knees and ankles.
Parts of the Space Suit
The Space Suit is made up of the: Liquid Cooling and Ventilation Garment,
the Primary Life Support Subsystem, the EMU Battery, the Pressure Vessel,
the Display and Controls Module (DCM), the Secondary Oxygen Pack (SOP), the
Improved Hard Upper Torso (HUT), the Pressure Helmet, and the Lunar
Overshoe. The Liquid Cooling and Ventilation Garment is a one-pieced suit
made of spandex. Water circulates through it to keep the astronauts body
temperature stable. The Primary Life Support Subsystem (PLSS) truly is the
most important part of the EMU. The PLSS consists of oxygen tanks, water
storage tanks, contaminant control cartridges, radio electrical power,
ventilating fans, a sublimator, and a microprocessor cauting and warning
systems. The astronauts wear the PLSS as a backpack. The EMU Battery is
mounted behind the main tank and above the contaminant control cartridge.
Each EMU uses a battery. The EMU is made of zinc cells connected in series
providing 27 amp-hours. The battery is the Extravehicular Activity (EVA)
electrical power source for the EMU. It can be recharged in the space
shuttle, and can be used for a minimum of 6 EVA missions. The Pressure
Vessel makes the space suits a livable place to be. It has seven layers of
material. These materials are called Kevlar, Dacron, and polyurethane
plastic. These layers contain the pressure in the space suit. The Display
and Controls Module (DCM) contains all the mechanical and electrical
operating controls necessary to operate the EMU. It also contains software
programs allowing it to run a series of system checks to view the condition
of the individual components of the EMU. The DCM can be seen directly
through the helmet or through the use of the mirrors mounted on the sleeves.
The Secondary Oxygen Pack (SOP) is located directly under the Primary Life
Support Subsystem (PLSS). The SOP functions as a back up system for all
life-support functions. The SOP contains two tanks. Each tank contains 1.2
kg of oxygen. When the oxygen pressure is low, the SOP oxygen supply
automatically turns on. The Improved Hard Upper Torso is a hard-shell
fiberglass structure that contains the Primary Life Support System and the
Display and Controls Module. It is attached to the legs, helmet, and arms
of the space suit. The pressure helmet consists basically of an aluminum
neck ring and a transparent shell made of polycarbonate plastic. The shell
is connected to the neck ring, which fits into and locks with a similar
neck ring on the torso limb suit. The Lunar Overshoe fits over both the
thermal meteoroid garment boot and the suit boot and is used for
extravehicular activity. It consists of an insulation and liner, and an
outer shell. The liner is Teflon-coated Beta cloth and the insulation is 13
layers of aluminized Kapton film separated by 12 layers of Beta
Marquisette. The sole part contains two additional layers of Beta felt
interspaced between the uppermost film and spacer layers. The outer shell
features a silicone rubber sole sewn to a laminated structure made up of
four layers of two-ply Beta Marquisette.
Homework Help: Science: Outer Space
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