Oh
plane engine start five four three two
one zero booster ignition and liftoff of
Columbia a new decade of spaceflight
begins
Roger Atlantis here go previa we're
aboard the space shuttle Atlantis 280
miles above the earth it's a busy time
up here right now two of our crew
members are preparing for one of space
travels most exciting adventures space
walking at NASA space walking is known
as extra vehicular activity but most of
the time we just call it an Eevee a EVs
allow us to do a lot of useful things in
space we can do many interesting
experiments in the payload Bay and test
new types of equipment we can also
spacewalk out to an orbiting satellite
to work on it but doing an Eevee a
involves a lot more than just opening
the door and stepping out into space
EPA's take us into an environment that's
entirely different from the one we live
in on earth an environment that's
hostile to human life that's because
space is almost a perfect vacuum and
that presents us with several problems
problems that take a good knowledge of
science to solve the first problem is no
air to breathe the Sun poses another
problem for space walkers because in
space there's nothing to protect us from
his harmful ultraviolet radiation the
radiation from the Sun also affects the
temperature in space in direct sunlight
the temperature can soared over 120
degrees Celsius more than hot enough to
boil water back on earth but when we get
away from the sun's rays the temperature
can drop to minus 100 degrees Celsius
far colder than Antarctica in the dead
of winter space debris is also a problem
so what makes the environment on earth
and the environment in space so
different
the answer is Earth's atmosphere it is a
dense mixture of nitrogen oxygen carbon
dioxide and water vapor that surrounds
our planet and makes life possible the
atmosphere
turns out harmful radiation and protects
us from debris flying through space as
it moves over the Earth's surface it
distributes heat from the Sun and
balances the temperature around the
world think of the atmosphere as an
ocean of gases when we're on the surface
of the earth it's like being on the
bottom of this ocean like the seawater
all of the ingredients at this
atmospheric ocean have weight too we
measure this force as pressure this
pressure pushes against us in all
directions but the pressure can also
change imagine that Jay and Jerry are on
the Earth's surface
we'll put Jamie in a dive suit and send
him to the bottom of the ocean on the
ocean floor
jay is under tremendous pressure but as
he starts back toward the surface the
pressure decreases when Jay reaches the
surface he's still under a small amount
of pressure that pressure is the weight
of the atmosphere and we call it
atmospheric pressure now watch what
happens when we put Gerry in a spacesuit
and send him up to the shuttle as he
rises through the atmosphere the
pressure continues to decrease until
he's in the near perfect vacuum of space
there's no longer an atmosphere and
there's no longer any pressure luckily I
was wearing a spacesuit during that
demonstration or I would have been in
big trouble let me show you what I mean
imagine that this balloon is my body and
the water inside is my body fluids well
put the balloon in a jar now we're going
to pump all the air or atmosphere out of
the jar so it will be similar to the
vacuum of space look what's happening as
air is removed from the jar the balloon
swells and the water begins to boil like
a soda pop that's the same thing that
would happen to me if I didn't have on a
pressurized suit
but where did pressure suits come from
aviation pioneers like Wiley Post were
among the first to use them that's
because those pilots who wanted to fly
at high altitudes had to come up with a
way to take their environment with them
early pressure suits came in all shapes
and sizes and although most of them were
stiff and hard to move around in they
laid the foundation for the suits we'd
later wear into space
go for docking we know that space is a
vacuum and we're going to have to take
our environment with us when we go Evie
a so let's build a spacesuit first it's
going to get pretty hot in the suit
after we've been working for a while so
we need a garment laced with small tubes
now we can flow chilled water through
the tubes to cool us off on top of that
we place a garment that creates the
pressure we need and holds in oxygen for
breathing now we need something to
protect us from the extreme hot and cold
of space and protect the entire suit
from tearing and from tiny meteorite
impacts we will use many layers of
thermal insulation covered by a tough
layer of white fabric let's give
ourselves a helmet to enclose our head
and will include a visor to protect our
eyes from the sun's ultraviolet
radiation on the front of the suit we'll
put a console with some valves and
gauges working everything else gave me
like oxygen tanks cooling water
batteries and radios we'll put in a
backpack called the primary life-support
system
donning the suit is just a matter of
putting on the pants just like I'd put
on a pair of jeans then slipping into
the top and locking the two halves
together at the waist next come the
gloves
and finally the helmet I've also got
some tethers to keep me from floating on
and this wrist mirror so that I can read
the dials on my life support system
putting the suit on is not the only
thing Jay and Jerry have to practice
they also have to practice working in
the suit and that's done here at the
weightless environment training facility
or wet F this big swimming pool holds
almost half a million gallons of water
that's big enough to hold a full-size
mock-up of the orbiter payload Bay
scuba divers are adding weights to Jerry
and Jay suits to make them neutrally
buoyant this means that they won't float
to the surface or sink to the bottom the
wet F isn't the perfect simulation of
weightlessness but it's the closest we
can come to on earth
we spend a lot of time in the water
practicing until
it's time for the real thing
during the next few hours Jerry and Jay
are going to experiment with new ways of
moving people and equipment around in
space in the future we'll be going EBA
to service satellites in orbit and to
help build space station freedom beyond
that people will work on the moon from
permanent lunar bases and even explore
the surface of Mars the spacesuit has a
big role to play in our use and
exploration of space and as new
challenges come our way we're going to
develop better suits but no matter where
the epa's take us one thing will always
remain the same as long as humans
venture into space we will always have
to take some of our environment with us
you