GOOD VIBRATIONS
You just bought a brand new car. Years of working hard and saving money have put that vehicle in your driveway. Now
imagine driving it at speeds in excess of 90 miles per hour down a road riddled with gaping potholes. The vibration
alone would turn your prized possession into a bucket of bolts.
The rigors of liftoff can do the same type of damage to expensive flight hardware and science instruments. A Delta II
launch vehicle puts out 700,000 pounds of thrust in order to break the grip of gravity. That thrust
can rattle any spacecraft tucked in the payload fairing at the tip of the rocket. That's why it's so important for the
Mars Exploration Rovers to undergo vibration testing.
Different rockets have different patterns of vibration. Engineers at the Jet Propulsion Laboratory determine which
vibration test to use based on which rocket will do the launching. In one type of test, the spacecraft and its
instruments are shaken in all directions. This flushes out any components that could come loose during launch and
jeopardize the mission. Another type of vibration test is the acoustic test. It simulates the noise that is generated
at liftoff. The spacecraft is put in a sound chamber and blasted with a high dose of decibels for at least one minute.
If you've ever sat near the speakers at a rock concert, you know how much you can "feel" the amplified noise.
Vibration testing will ensure the Mars Exploration Rovers are "rock solid" so that years of work and millions of
dollars won't be lost during the stress of launch.
Web content editor/writer: Pamela R. Smith
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