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One of the most striking
features of the James Webb

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Space Telescope
is the sunshield,

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probably because it's about
the size of a tennis court.

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Now that's too big to be
sent into space that way.

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So at launch, it's in a
folded up configuration.

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When the James Webb
Space Telescope

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reaches its destination one
million miles from Earth,

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the sunshield is then deployed.

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Different contractors are
working right now together

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on a mechanism or
several mechanisms

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to control the
sunshield's deployment.

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One of those is Northrop
Grumman's Astro Aerospace here

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in Carpinteria, California.

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One of the lead project
engineers here at Astro

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Aerospace is Larry Heinlein.

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Hey, Larry.

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So what exactly are you
guys working on here?

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This is a mid-boom assembly for
the James Webb Space Telescope.

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So what exactly is
mid-boom assembly?

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So there's one base tube.

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And there's five
deploying tubes.

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The five deploying
tubes deploy out.

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And as they deploy
out, they unfold

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the layers of the sunshield.

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[MECHANICAL WHIRRING]

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And you have separate
tubes because?

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Because during launch, it needs
to stove within about five feet

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of length.

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And when it's fully
deployed, it's about 25 feet.

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But on the end of that boom
is a 5-foot long spreader bar,

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which the sunshield
layers are attached to.

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Oh, OK.

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That puts the layers of the
sunshield in position, right?

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That's correct.

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OK, kind of reminds me
of an antenna of sorts.

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Yes, it kind of looks like
your old-fashioned deploying

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antenna.

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So, Larry, how do you
make these tubes extend?

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Well, inside the
carbon graphite tubes

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is something that we
call the STEM deployer.

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And Tim Martinez will
help explain that.

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This is called a STEM deployer.

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And this amounts to the
bottom of the base tube.

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And this is what
drives the assembly

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and pushes the tubes up.

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And the way it works
is that it pushes

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this material called STEM out.

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And the concept is
like a tape measure.

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So when it's coming
out, it becomes round.

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But when it's around this
spool that's inside, it's flat.

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And there's a motor that
drives the whole thing out.

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It doesn't feel very heavy.

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But it's strong?

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Yeah, it's made out
of very thin sheet

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of corrosion resistant steel.

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But that's what's
great about it.

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It's really light.

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But it can push up 100 pounds.

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And then there's also a
requirement to pull back.

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And so it can actually
pull back 400 pounds.

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And why would you
even pull back?

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Once the booms are completely
deployed, it pulls back.

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And the tubes are
connected to a cable which

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tensions the whole sunshield and
separates the five membranes.

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Thanks for joining us
for another edition

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of Behind the Webb.

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[MUSIC PLAYING]

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