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Oh

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plane engine start five four three two

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one zero booster ignition and liftoff of

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Columbia a new decade of spaceflight

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Roger Atlantis here go previa we're

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aboard the space shuttle Atlantis 280

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miles above the earth it's a busy time

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up here right now two of our crew

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members are preparing for one of space

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travels most exciting adventures space

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walking at NASA space walking is known

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as extra vehicular activity but most of

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the time we just call it an Eevee a EVs

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allow us to do a lot of useful things in

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space we can do many interesting

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experiments in the payload Bay and test

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new types of equipment we can also

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spacewalk out to an orbiting satellite

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to work on it but doing an Eevee a

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involves a lot more than just opening

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the door and stepping out into space

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EPA's take us into an environment that's

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entirely different from the one we live

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in on earth an environment that's

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hostile to human life that's because

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space is almost a perfect vacuum and

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that presents us with several problems

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problems that take a good knowledge of

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science to solve the first problem is no

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air to breathe the Sun poses another

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problem for space walkers because in

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space there's nothing to protect us from

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his harmful ultraviolet radiation the

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radiation from the Sun also affects the

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temperature in space in direct sunlight

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the temperature can soared over 120

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degrees Celsius more than hot enough to

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boil water back on earth but when we get

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away from the sun's rays the temperature

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can drop to minus 100 degrees Celsius

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far colder than Antarctica in the dead

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of winter space debris is also a problem

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so what makes the environment on earth

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and the environment in space so

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different

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the answer is Earth's atmosphere it is a

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dense mixture of nitrogen oxygen carbon

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dioxide and water vapor that surrounds

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our planet and makes life possible the

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atmosphere

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turns out harmful radiation and protects

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us from debris flying through space as

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it moves over the Earth's surface it

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distributes heat from the Sun and

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balances the temperature around the

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world think of the atmosphere as an

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ocean of gases when we're on the surface

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of the earth it's like being on the

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bottom of this ocean like the seawater

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all of the ingredients at this

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atmospheric ocean have weight too we

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measure this force as pressure this

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pressure pushes against us in all

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directions but the pressure can also

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change imagine that Jay and Jerry are on

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the Earth's surface

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we'll put Jamie in a dive suit and send

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him to the bottom of the ocean on the

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ocean floor

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jay is under tremendous pressure but as

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he starts back toward the surface the

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pressure decreases when Jay reaches the

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surface he's still under a small amount

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of pressure that pressure is the weight

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of the atmosphere and we call it

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atmospheric pressure now watch what

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happens when we put Gerry in a spacesuit

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and send him up to the shuttle as he

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rises through the atmosphere the

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pressure continues to decrease until

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he's in the near perfect vacuum of space

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there's no longer an atmosphere and

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there's no longer any pressure luckily I

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was wearing a spacesuit during that

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demonstration or I would have been in

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imagine that this balloon is my body and

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the water inside is my body fluids well

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put the balloon in a jar now we're going

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to pump all the air or atmosphere out of

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the jar so it will be similar to the

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vacuum of space look what's happening as

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air is removed from the jar the balloon

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swells and the water begins to boil like

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a soda pop that's the same thing that

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would happen to me if I didn't have on a

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but where did pressure suits come from

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aviation pioneers like Wiley Post were

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among the first to use them that's

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because those pilots who wanted to fly

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at high altitudes had to come up with a

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way to take their environment with them

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early pressure suits came in all shapes

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and sizes and although most of them were

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stiff and hard to move around in they

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laid the foundation for the suits we'd

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go for docking we know that space is a

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vacuum and we're going to have to take

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our environment with us when we go Evie

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a so let's build a spacesuit first it's

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going to get pretty hot in the suit

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after we've been working for a while so

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we need a garment laced with small tubes

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now we can flow chilled water through

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the tubes to cool us off on top of that

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we place a garment that creates the

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pressure we need and holds in oxygen for

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breathing now we need something to

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protect us from the extreme hot and cold

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of space and protect the entire suit

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from tearing and from tiny meteorite

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impacts we will use many layers of

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thermal insulation covered by a tough

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layer of white fabric let's give

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ourselves a helmet to enclose our head

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and will include a visor to protect our

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eyes from the sun's ultraviolet

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radiation on the front of the suit we'll

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put a console with some valves and

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gauges working everything else gave me

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like oxygen tanks cooling water

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batteries and radios we'll put in a

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backpack called the primary life-support

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system

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donning the suit is just a matter of

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putting on the pants just like I'd put

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on a pair of jeans then slipping into

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the top and locking the two halves

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together at the waist next come the

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and finally the helmet I've also got

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some tethers to keep me from floating on

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and this wrist mirror so that I can read

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the dials on my life support system

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putting the suit on is not the only

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thing Jay and Jerry have to practice

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they also have to practice working in

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the suit and that's done here at the

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weightless environment training facility

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or wet F this big swimming pool holds

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almost half a million gallons of water

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that's big enough to hold a full-size

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scuba divers are adding weights to Jerry

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and Jay suits to make them neutrally

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buoyant this means that they won't float

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to the surface or sink to the bottom the

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wet F isn't the perfect simulation of

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weightlessness but it's the closest we

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we spend a lot of time in the water

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it's time for the real thing

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during the next few hours Jerry and Jay

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are going to experiment with new ways of

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moving people and equipment around in

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space in the future we'll be going EBA

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to service satellites in orbit and to

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help build space station freedom beyond

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that people will work on the moon from

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permanent lunar bases and even explore

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the surface of Mars the spacesuit has a

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big role to play in our use and

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exploration of space and as new

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challenges come our way we're going to

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develop better suits but no matter where

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the epa's take us one thing will always

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remain the same as long as humans