amazing videos and photographs, and while images of Mars have taught humanity many things, it always seems as though a silent cosmic movie is being watched.
Right from the very beginning, while Perseverance was still being built, scientists knew they had to prepare the rover for its main mission - to find signs of life on Mars. However, a French-US team was convinced that sound could advance understanding of the planet. As a result, they went ahead and installed audio gear on the rover as well. They then waited patiently for the sounds of Mars to come through.
A new study published in Nature reveals that sound on Mars behaves very differently from how it does on Earth. The speed of sound is slower on the Red Planet so sounds tend to fade away faster. Mars is also dominated by deep silences only broken by howling winds and dust storms. Perseverance has been recording sounds since February 19, 2021, one day after it landed, with all sounds recorded between 20 Hz and 20 kHz making them within the human audible spectrum.
Mars Sounds Just Like It Should
At first, scientists working with the Perseverance audio samples thought the microphone had somehow been damaged and was broken. That’s how silent Mars is. Listening closely to the the Mars helicopter’s rotor can be heard. The strangest thing scientists discovered is that the speed of sound is not constant on Mars. High frequencies dim out very quickly while low frequencies tend to last longer.
The study focused on sound behavior to model how sound waves move in the Martian atmosphere as a medium. On Earth, sound travels at 343 meters per second. On Mars, however, it travels at between 240 and 250 meters per second depending on whether it is low-pitched or higher-pitched sounds. “All these various factors would make it difficult for two people standing only five meters apart to have a conversation,” the paper said.
The reason why sound behaves strangely on Mars is due to the atmosphere being 96% CO2, compared to 0.04% on Earth. This is in addition to the very low atmospheric surface pressure that's 170 times lower than Earth. Even now Perseverance continues recording sounds as it has done for more than a year. In fact, if all of the Perseverance Mars tracks were combined, the result would last more than five hours, making for quite the historical playlist.