NASA's Perseverance Mars rover hears an alien soundscape that changes with the seasons

Cue Simon & Garfunkel — Mars is all about the sound of silence.

NASA's Perseverance rover has been recording the ambient sounds on Mars for the past year, and scientists have trimmed those recordings to a five-hour "Martian playlist." The main takeaway? It's very quiet on Mars. In fact, the few natural noises on the Red Planet, including wind, are about 20 decibels quieter than the same noises on Earth.

"It is so quiet that, at some point, we thought the microphone was broken!" Baptiste Chide, a postdoctoral fellow at Los Alamos National Lab who is working with the sound recordings, said in a statement.

Related: Listen to the Mars wind blow in these 1st sounds from the Perseverance rover

Despite having limited audible material to work with, scientists are still making discoveries. They determined, for example, that Martian wind has extreme variability, abruptly changing from a gentle breeze to violent gusts.

The researchers have also proved a hypothesis about unusual sound behavior on Mars. By using specifically timed laser sparks emitted from the Perseverance rover, the team has studied sound dispersion on Mars, confirming that high-pitched sounds travel faster than low-pitched ones.

"Mars is the only place in the solar system where that happens in the audible bandwidth because of the unique properties of the carbon dioxide molecule that composes the atmosphere," Chide said.

The carbon dioxide in Mars' atmosphere also plays a role in the seasonality of sound, the researchers suggested. As carbon dioxide freezes at the Martian poles during the winter, the atmosphere becomes less dense, so the volume of sound varies about 20% between the seasons on Mars.

Chide presented the findings, which are also described in a paper, on Wednesday (May 25) at the 182nd meeting of the Acoustical Society of America in Denver.

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