Two microphones have recently been placed on Mars and their recordings have now yielded some startling conclusions.

This is apparent from an extensive analysis of the sound recordings, which appeared in the magazine Nature† The authors of the study base their conclusions mainly on recordings made by a microphone that adorns the mast of Mars rover Perseverance. In addition, the analysis also included sound recordings made by a microphone on the chassis of the rover. Where previous Mars rovers already showed what the Martian surface looks like by means of beautiful photos, thanks to these microphones we can now hear for the first time what Mars sounds like. And an analysis of the sound recordings now yields quite a number of surprising conclusions.

Speed ​​of sound

For example, the speed of sound on Mars appears to be much lower than on Earth and to depend on the frequency of the sound. Where sounds on Earth usually travel at a speed of 343 meters per second, they are considerably less in a hurry on Mars. High frequency sounds travel at a speed of 250 meters per second, while lower frequency sounds get stuck at a speed of 240 meters per second.

Different atmosphere

It can all be traced back to the fact that Mars’ atmosphere is very different from Earth’s. For example, the Martian atmosphere is much thinner and colder and consists for the most part of CO2. Because researchers already had a good idea of ​​the composition of Mars’ atmosphere prior to the launch of Mars rover Perseverance, they had already expected that the speed of sound on Mars would be different than on Earth, but it has now also been proven for the first time. .

In addition, the sound recordings indicate that sounds on Mars – again due to the thin atmosphere – do not get that far. While sounds on Earth can be heard tens of meters away, low-frequency sounds on Mars don’t extend much further than 8 meters. And high-frequency sounds kick it even less.

Of course, it’s really cool to hear sounds recorded on Mars. But that hasn’t been the primary reason for sending a microphone to Mars. By recording sounds, researchers can also learn more about the atmosphere through which they travel. In addition, the microphones offer researchers an additional way to assess the health and functioning of Mars rover Perseverance. For example, an unusual sound can indicate that something is not quite right.

Silence

The conclusions described above may suggest that the microphones on Mars were working overtime. But nothing is less true; where the silence here on Earth is sometimes hard to find, it is very different on Mars, the researchers discovered. “At one point we thought the microphone was broken, it was that quiet,” says researcher Sylvestre Maurice. That too can be traced back to that thin atmosphere. “Mars is very quiet because of the low air pressure,” said researcher Baptiste Chide. “But,” he adds immediately. “The pressure changes with the seasons on Mars.” And that means it could be getting a little noisier on the planet as autumn approaches on Mars. “We are now entering a season where the air pressure is higher,” said Chide.

Scientists will continue to listen to their ear – through the microphones – in the coming period. “It’s a new way of research that we haven’t used on Mars before,” says Maurice. “I expect many more discoveries to be made.”

Now that the microphones give researchers an increasingly clear picture of how sound behaves on Mars, they can also reveal how sounds we regularly hear here on Earth would sound on Mars. An anthology, from top to bottom: birdsong in a busy city, a truck backing up, waves in the ocean and spoken (famous) words.