Since arriving on Mars in February 2021, Perseverance has managed to capture more than five hours of recordings of the Red Planet’s sound environment. If you can’t hear Martians, you can perfectly make out the sound of the wind. The first observation is therefore that the activity on Mars is very calm: apart from this wind, it is difficult to identify other natural sound sources.
An international team of researchers, led by the Frenchman Paul Sabatier, including scientists from the CNRS and the Higher Institute of Aeronautics and Space, has just published in Naturean analysis of these sounds.
There are two speeds of sound on Mars
They were particularly interested in the shock waves generated by the robot, but also in the noise of its laser on the rocks. They thus show that the speed of sound is lower on Mars than on Earth, around 860 km/h once morest just over 1200 km/h here. But the most surprising thing is that there are actually two speeds of sound on Mars: one for highs and one for lows. In addition, the sound attenuation is stronger there, particularly the highs which can be lost very quickly, even at close range, unlike the lows. This means, for example, that it would be very difficult for two people only a few meters apart to get along.
Note that all these sounds were recorded using a microphone developed in France, in Toulouse. In the future, other robots equipped with this type of microphone might improve understanding of planetary atmospheres, on Mars and elsewhere.
