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Resonance -- Clint Black on the Power of Acoustics
02.03.06
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Clint Black on the Power of Accoustics

[ STANDARD OPENING]

MIKE ARRINGTON:
Whether you're launching a career in music like that of Country star Clint Black ...

Or, launching a rocket ship like NASA's Space Shuttle...

… You'd better use a lot of SOUND judgment! And, in case you haven’t heard… the two have a lot in common… so says Clint Black in a recent Public Service Announcement campaign he recorded for NASA aimed at getting students interested in math and science… including the power of acoustics. And, he does so with the musical question…

CLINT BLACK:
"Did you know my guitar is like a rocket?"

ARRINGTON:
And, aerospace engineer Rodney Rocha of NASA's Johnson Space Center in Houston... you might say... is singing from the same sheet of music.

RODNEY ROCHA:
"They both resonate,"

ARRINGTON:
The popularity of music and the guitar, as well as the excitement of space travel may strike a chord that brings science -- even rocket science –down to Earth for America's students.

CLINT BLACK:
“When you pick up an acoustic guitar, one of the first things you'll notice is the body is basically an air chamber. The shape of the instrument is designed to be 'in tune' with the sound from the strings. And you’ll notice that it’s made with lightweight and flexible wood. It all works together to let sound waves build upon themselves to amplify and enrich the music. We call this 'resonance' and it's a big part of what makes a great guitar.”

“Rockets resonate too, but what’s good for your guitar isn’t always good for your spacecraft. Unchecked resonate vibrations can get so strong they damage your ship. Building rockets with less flexible material helps control sound vibration, but that’s not the only technique spacecraft designers use. Sometimes they even modify the rocket to detune it from itself.”

ARRINGTON:
The tie-in there between the pleasant acoustics of music, and the potentially deadly physical forces that resonate through spacecraft is neither a stretch... nor purely academic. Anyone who has witnessed a Space Shuttle launch knows you don't just see it, and hear it... you FEEL IT!

[SFX - SHUTTLE LAUNCH! ]

ARRINGTON:
And if anyone has ever wondered why NASA makes people watch a launch from miles away... Engineer Rodney Rocha explains that at THAT particular show, nobody wants a front row seat.

RODNEY ROCHA:
"When the shuttle lifts off, the main engines roar so loudly that a person standing near the pad might be killed—not just by the heat of the exhaust, but by the intense sound of the engines,"

ARRINGTON:
So just imagine the challenge NASA faces in designing spacecraft that can tolerate that type of strumming as it roars toward orbit.

RODNEY ROCHA:
"We can’t let these sounds find and over-excite a sympathetic resonance. If they do the sound is amplified into structural stress, vibrations increase. Bolts can become unscrewed, covers ripped off, joints loosened."

CLINT BLACK:
"They damage your ship, and really shake up your mission."

ARRINGTON:
The engines cause a major acoustical challenge all by themselves. But there are other sources of noise as well, like the air that rushes past the spacecraft as it hurtles through the atmosphere.

RODNEY ROCHA:
"You can get a good idea of this kind of aerodynamic noise just by rolling down your car window while driving,"

ARRINGTON:
Now imagine what it might sound like if you did that while going from a standstill to 17,500 miles per hour in about eight minutes. In either case, for safety sake, don't stick your hand out.

Safely now in orbit, the noises, and the challenges they present continue with every firing of a maneuvering thruster, and certainly when they dock with another spacecraft like the International Space Station.

RODNEY ROCHA:
"The goal of engineers is, by design, to make sure these vibrations die out quickly, before they do any harm. In the language of musicians, rocket designers must avoid sustain."

ARRINGTON:
The designers of guitars, on the other hand, have just the opposite challenge. Composers and performers need sounds that DO sustain for a long time as well as those that don't. If you play guitar, like David Higganbotham, you probably recognize this sound as a High E, the top string, or in the language of engineers, 82 Hz. By combining a variety of sounds, David composes his own music... hit it Dave.

[ Brief Music Up Full ]

ARRINGTON:
The art ...

[ Crossfade between David's music and a Shuttle launch ]

ARRINGTON:
... and science of accoustics.

NASA engineers use jam sessions of their own to make sure that rockets will survive the tremendous acoustical forces that will be generated during flight. They rehearse until they get it right. And their NASA test facilities are equipped with speakers that really COULD blow you away.

RODNEY ROCHA:
"There are huge sonic chambers where we take pieces and components of our rockets and expose them to loud noises.One of our 165 decibel acoustic horns at JSC can make as much noise as a space shuttle main engine."

ARRINGTON:
Through such tests, engineers fine tune their design, and they have a proven track record that dates back four decades to the Apollo program.

NEIL ARMSTRONG:
“That’s one small step for a man…”

ARRINGTON:
In those days, NASA engineers tested sections of Saturn rockets using loud sounds in special laboratories. And when the space shuttle came along those components were tested in the same way. Now with America on a return course to the Moon, on to Mars and beyond, how might the future Crew Exploration Vehicle, or CEV, be fine tuned?

RODNEY ROCHA:
"I'm sure the Crew Exploration Vehicle will get its turn in a sound chamber, too."

ARRINGTON:
And one thing they will bear in mind...

RODNEY ROCHA:
"The most vulnerable articles tend to have low mass and lots of surface area—like a guitar."

CLINT BLACK:
"So you see, controlling your sound is just as important to rocket scientists as it is to musicians."

ARRINGTON:
The public service announcement campaign is designed to help make sure there will be enough American scientists and engineers to meet the technological challenges of the next generation.

This podcast was written, produced, and narrated by Mike Arrington, and it was based upon a story at Science@NASA written by Tony Phillips. David Prince was the audio editor and additional audio support was provided by Royce Bowie. Original music was written and performed by David Higginbotham.

[ :20 - OUTRO, CREDITS and FOR MORE INSO LINK ]

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