Many people have wondered what it would be like to walk on the surface of Mars, exploring the red planet that has been a continual source of fascination for humankind. Colorful panoramic images from both the Viking landers and more recently Mars Pathfinder have given us all a view of the surface of Mars in detail, and spurred yet more interest in this unique environment that could almost best be described as a cold, high altitude desert.

But as we explore Mars, perhaps someday walking around on its surface, what would we hear?

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. While the atmosphere on the surface of Mars is indeed very thin, amounting to less than 1% of the pressure on Earth, laboratory experiments and theoretical calculations show that it is possible that sounds on Mars could be detected by standard microphone technology.

The original Mars Microphone instrument was constructed for the ill-fated NASA Mars Polar Lander (MPL) mission, which lost contact with Earth shortly after its descent to the Martian surface and was never recovered. Nevertheless, during the MPL mission we demonstrated that a low-cost (<$100,000), small (25 cc) and lightweight (50g) instrument could be constructed for a major NASA planetary mission.

Interest in the Mars Microphone project was so intense that immediately following the loss of MPL, a second opportunity to fly the microphone experiment was provided by the Centre National d'Etudes Spatiales (CNES), the French space agency, on the NetLander mission to Mars in 2007. NetLander will land four small identical landers on Mars to study the atmosphere and the planetary subsurface and interior core. The Mars Microphone experiment is currently being redesigned to fit within the camera head of the NetLander probes being built by the German space agency (DLR).