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DAISY: At NASA, safety is job
one.

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Engineers go to extreme lengths
to ensure safe

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travels for astronauts...

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We’ll show you how they do it,
next on Real World.

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? [music] ?

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FLIGHT ATTENDANT: An oxygen
mask will automatically drop

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from a compartment above your
seat. To start the...

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DAISY: When you fly commercial,
you know there

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are lots of safety measures in
place...

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But if you go for a ride in the
Space Shuttle, multiply

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that to the 10th power and
you’ll get an idea of how

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much safety goes into every
Space Shuttle mission.

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NASA engineers divide shuttle
safety into three areas:

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Pre-flight, flight, and
post-flight.

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Pre-flight safety includes
planning the mission,

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testing Shuttle components and
procedures,

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and spacecraft design.

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In fact, the Shuttle recently
underwent some upgrades to

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make missions safer than ever
including a

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Cockpit Avionics Upgrade.

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It’s kind of like getting a
whole new set of gages

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for your car’s dashboard.

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The Cockpit Avionics Upgrade
brings news hardware and

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software, providing the crew
with better informational

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displays and warning functions.

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This upgrade helps the crew get
data on the

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Shuttle’s performance more
quickly.

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During flight, one of the
coolest safety features is a

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monitoring system for the
shuttle’s

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Thermal Protection System.

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It uses the Remote Manipulator
Arm along with an

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Orbiter Boom Sensor System. The
Orbiter Boom extends the

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Manipulator Arm and has a
camera at its end.

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While the Shuttle is orbiting,
astronauts take

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hundreds of images of the
Shuttle’s exterior.

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These images are beamed back to
earth and the Mission

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Evaluation Room where engineers
examine them

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looking for any damage that
might have occurred

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during the mission.

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Of course, while in flight,
NASA ground control is

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constantly monitoring and
checking every aspect

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of the mission and the Shuttle.

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MIKE MOSES: You get most of
your data by flying...

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DAISY: Mike Moses is Launch
Integration Manager for the

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Space Shuttle Program, and he
eats, sleeps,

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and breaths safety.

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MIKE: The real art of making
sure we stay safe every time

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is to look at that data.

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DAISY: Safety issues are again
addressed during post-

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flight, when NASA engineers
focus on how all the systems

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performed during the mission.

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They gain a little more
knowledge each time up.

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MIKE: On the last flight we saw
a signature as we were

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going uphill for ascent, one of
the pressures just didn’t

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respond the way it was supposed
to.

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DAISY: It didn’t cause any
problems during the mission,

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STS-126, but after landing,
engineers rolled up their

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sleeves to take a closer look
at the issue.

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MIKE: When we started looking
at it we found

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the valve itself was cracked.
DAISY: The pressure that Mike

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is talking about inside the
Shuttle’s external fuel tank

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is measured in pascal units.

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For example, the pressure of
the air all around us at sea

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level... called standard
atmospheric pressure...

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is 101,325 pascal.

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Pascal units measure force per
unit area, such as 1

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newton per square meter. A
Newton is a unit of force.

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It was the release of pressure
that caused the

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valve to crack.
MIKE: This is the inside of

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the valve so there’s a sleeve
outside of this and it goes

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up and down. And what it’s for
is, the big external tank

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has hydrogen and oxygen in it,
and we need to keep them

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pressurized to feed the engines
at the right rate.

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So we kind of boot strap, we
siphon off a little bit of

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that hydrogen, burn it through
the engine, and make

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it into hot gas, and then we
send it back up into the tank

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to pressurize it. So this valve
controls the rate at

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which we keep that tank
pressurized. So this little

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tiny lip, here, it was
fluttering up in down in...

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we call it the wind,
basically... as the hydrogen

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rushed past, it made this thing
flap and eventually it

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stressed it and broke it off.
And we never expected that

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there would be that type of
flow past this little valve.

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When this valve was designed,
now, probably 30 year ago,

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it was state of the art. It’s
exactly what it should

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do. Now that we have all these
advanced computational

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fluid dynamic modeling, you
can, in a computer, model

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exactly how this flow works and
know the exact velocities

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and speeds. It’s absolutely
amazing.

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DAISY: Thanks to computer
modeling and math, engineers

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are able to visualize how the
flow of hydrogen and nitrogen

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caused the valve to fail.

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From there, they can
calculate the likelihood

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that the component will fail
again.

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MIKE: We did a whole bunch of
math to show basically that

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when this thing cracks we know
how the little stresses

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will propagate around and we
can say it probably won’t be

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more than a 90 degree piece
that breaks off. And then you

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want to look at what that
little piece does as it goes

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downstream. Is it going to hit
a line and make a hole?

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Is it going to let too much
hydrogen through so the tank

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gets over pressurized? So we
boiled our way down through

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all those options. And
basically, at the end of the

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day, we found that it was
acceptable. The probability

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of any one of those things
happening was pretty small.

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DAISY: The issue delayed the
next flight, STS-119, by two

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weeks, but all that math
certified that that

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mission would go off safely.

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MIKE: Space flight is really
hard and it’s really hard

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because it’s so
complicated... everything has

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to play just right with each
other.

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DAISY: So as you can see, when
it comes to safety, NASA

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engineers really sweat the
details...doing all they can

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to make sure crews come back
safely.

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? [music] ?