The goal of the Mars Microphone experiment, as its name implies, is to develop acoustic sensors -- microphones -- to record sounds on the surface of Mars. Given that sound waves need an atmospheric medium through which to travel, many people are surprised to learn that any sounds at all can be heard on Mars. The atmospheric pressure on the surface of the Red Planet is small, amounting to less than 1 percent of Earth's sea level pressure. But even at Mars' low pressure, acoustic signals within the frequency range of the human ear can be detected. And while the atmosphere of Mars is very different from Earth's, consisting mostly of carbon dioxide, there are similarities between these environments that should make the sound data worthwhile.
For example, there is weather on Mars, including winds, sandstorms, and dust devils, which are little tornadoes caused by local weather patterns. The Mars Microphone may be able to hear these winds and perhaps even a type of lightning within sandstorms. The microphone will also record noises made by a lander, such as the sound of a robotic arm digging for soil samples. The microphone can be triggered randomly by naturally occurring sounds or it can be programmed to listen to specific lander actions.
However, the most exciting sounds are likely to be ones that we don't even know about yet. Experience has demonstrated that whenever a new instrument is developed and flown in space, we learn something new about extraterrestrial environments, and therein lies the true spirit of the Mars Microphone concept. The instrument will also bring the public closer to Mars exploration. The sounds picked up by the Mars Microphone will be available to the public so that anyone will be able to hear for themselves what it sounds like on Mars.
Recordings from the Mars Microphone
Before and during the microphone's testing and development for the Mars Polar Lander and Netlander missions, the microphone system was rigorously tested here on Earth. The sounds you can listen to through the links below were recorded by the Mars Microphone.
Suppose you found yourself on Mars without a spacesuit. What would you say? Probably "Help!" because the air is more than 100 times thinner than Earth's, far too thin to breathe, and, furthermore, it's primarily carbon dioxide, a nasty toxin.
Your understandably poignant plea wouldn't go far in the Martian air, which will mute even the loudest screams to near whispers. Stranger still, your voice would be lower pitched than on Earth because of the lower sound speed. But suppose, suspending disbelief for a short while, that you really could speak on Mars. How would you sound?