Open with music.
Narrator: If the Mars rovers could talk, what a tale they'd tell of their dusty, bumpy journey. Finally we hear from them.
I'm Jane Platt with NASA's Jet Propulsion Laboratory in Pasadena, California.
For the past six years, we've marveled at all the diverse pictures from Mars, beamed back by Spirit and Opportunity. You've heard scientists and engineers waxing poetic about the rovers. But you've never heard the rovers themselves speak -- until now.
Audio clip of rover Spirit
Narrator: OK, so that's not exactly Spirit talking. The rovers have no onboard microphone. But that is audio the engineers made from an instrument on the rovers -- in this case, from Spirit. A motion sensor, called an accelerometer, measures bumps and vibrations in the rocky Martian road as the rovers roam around. The sensor's data were converted to audio files. The original purpose -- to help determine whether Spirit had bumped into a rock. A familiar concept to us.
Belluta: Actually, you're driving your car, and all of a sudden you hear a funny noise, a funny sound, and from the type of sound, you can have a hint of the type of trouble that your car might have.
Narrator: Rover driver Paolo Bellutta of JPL. They do have software to analyze the data from the rover's accelerometer, but Bellutta says they figured, why not try using our good ol' human ears.
Bellutta: On compact discs, the sound is encoded in numbers, so I followed the same principle. I took the numbers from the accelerometer and generated a file that has the same format as a compact disc and then converted to an mp3, the file format that we all use in our iPods and other devices.
Narrator: The audio frequency was super-low, much too low for us Earthlings to hear. So engineers sped things up about a thousand times, so we could hear it. OK, so this audio clip was made from sensor data in 2005, when Spirit was exploring "Husband Hill."
Repeat of audio clip of rover Spirit
Narrator: And now listen to audio from Opportunity's recent journeys. You can tell she's had smoother sailing than Spirit. Fewer bumps and vibrations.
Audio clip of Opportunity
Narrator: Now that we've whetted your appetite, if you want to hear the longer versions of those audio clips, go to http://bit.ly/9I36I9 , that's bit.ly/9I36I9 , http://bit.ly/9I36I9. And for more info on the rovers, visit www.nasa.gov/rovers . Thanks for joining us for this podcast from NASA's Jet Propulsion Laboratory.