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Hi my name is Elizabeth Thiel.

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I'm from Komachin Middle
School in Washington state

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and you're watching NASA Now.

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Hi, I'm Matt and
this is NASA Now.

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At NASA, every part
of the manufacturing

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and assembly process of
a spacecraft is critical

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to ensuring mission success.

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Today, we'll meet an expert

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who explains the science
behind welding and why a weld

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that works on Earth doesn't
mean it will hold up in space.

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That's ahead, first here's
what's happening at NASA Now.

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Did water ever exist on Mars?

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Recent images taken from NASA's
Mars Reconnaissance Orbiter

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reveal that it could have.

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This image of the McLaughlin
Crater, stretching 57 miles wide

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by 1.4 miles deep,
shows layered,

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flat rocks containing
carbonate and clay minerals

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that usually form in
the presence of water.

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Scientists also observed small
channels close to the bottom

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of the crater that could have
marked the surface of a lake.

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This observation,
combined with the lack

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of any large inflow channels,

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suggest this may have
once been the site

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of a groundwater-fed lake.

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Building a spacecraft that
can withstand the rigors

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of space takes a lot
of testing and design.

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When the design is ready and
it's time to build a prototype,

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that's where welding engineer
Shane Brooke and hundreds

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of other people have a big role.

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Shane took some time to
give us a firsthand look

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at the important
role welding plays

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as human beings push further
and further into space.

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[ Music ]

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Welding is used on everything.

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We use it on engines.

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We use it on cryogenic tanks.

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It's used with the space
frame of the shuttle.

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It's used in electronics,
so there's a wide array

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of welding processes that a lot
of people don't give credit to,

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but that are, indeed,
welding processes.

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[ Music ]

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Generally speaking, there
are two types of welding.

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There's fusion welding
and solid-state welding.

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Some of the fusion processes,
we're more familiar with,

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you know, that's
the stick electrode

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or the gas metal arc welding,
mostly what you find in shops

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and garages across America.

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The solid-state welding
is a bit different

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in that it doesn't use melting.

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For example if we have this
complicated aluminum alloy,

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it's difficult to
fusion weld some

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of these materials
that we create.

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But we can use the
friction stir process

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because it doesn't
melt the material

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to join the two parts together.

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There is no external
heat source.

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It's friction alone
to heat the material

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to reach this plastic
state, much like if you were

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to just rub your hands
together really hard

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and really fast,
you generate heat.

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[ Music ]

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There are two types of
friction stir welding.

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We classify them as
conventional and self-reacting.

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They both use similar
heating processes.

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Conventional has a
one-sided pin tool

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where we plunge into the part.

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We plasticize it, form it
into like a taffy or a putty.

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We have an anvil
behind the part.

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So as we plunge into the part,
the anvil reacts that load

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so the part doesn't move, and
then it's forged together.

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The self-reacting process
does not have an anvil.

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So we basically have a
shoulder on both sides pushing,

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canceling out the loads,
traversing through the joint.

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So as both shoulders rotate,

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the pin will traverse
through the joint.

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The material is plasticized
and forged together

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with a pinching load and we
have a perfectly welded part.

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[ Music ]

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Currently, we're using
friction stir welding

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for large space vehicle
cryogenic tank production.

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These large vehicle tank
structures are aluminum,

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and aluminum, as we know, is
a softer metal than steel.

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So for the larger space
applications, it works great

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for cryogenic tank production.

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Looking towards the future at
different high-strength steels,

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we're currently working on
friction stir technology

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that will allow us to weld
these higher strength steels.

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[ Music ]

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Not necessarily, different
materials have different

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properties at different
temperatures.

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So here on earth at 70 degrees a
weld may be great but if you get

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into space at -300 degrees
where it's very, very cold now

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that weld may be very brittle.

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So we don't want it to fail when
the astronauts need it most.

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We do all sorts of testing,
as you could imagine.

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There is testing called,
nondestructive evaluation,

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where we use ultrasonic
technology, x-ray technology,

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dye penetrate inspection, where
we inspect these welds to see

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if there are any surface
defects or volumetric defects.

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We also do mechanical testing

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where we will weld
up a test panel.

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We'll cut it into strips,

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and we will mechanically
pull the weld until it fails.

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And then based on that
strength or that number,

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we know how strong that weld is.

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And then we can use
those numbers

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to factor how safe is
it to fly this vehicle.

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[ Sound Effects ]

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Did you know that
a material used

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to make jet engine fan
cases is also being used

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in sports and healthcare?

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Together, NASA and private
industry have developed a carbon

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fiber, reinforced composite.

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This braided, lightweight
material is being used

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to create jet engine fan
cases that are stronger

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and lighter-making them safer
and more fuel-efficient.

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This same technology is being
used to create more durable,

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lightweight sports equipment
and prosthetic devices.

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Now you know.

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[ Sound Effects ]

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You've just learned
how welding is critical

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to holding together a spacecraft
during the launch process

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and in the harsh
environment of space.

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Now it's time to test your
own engineering ability.

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Here's a great project where you

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and your students can build
a spacecraft structure strong

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enough to withstand three
successful launches.

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Look for Engineering
Design Challenge:

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Spacecraft Structures.

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You'll find it by checking
out the extension activity

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for this program on the NASA
Explorer Schools Virtual Campus.

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Well that's it for NASA NOW.

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Be sure to visit our facebook
page and leave a comment.

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We'll see you next
time on NASA NOW!

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