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Audio recordings were evaluated.  Mars is a silent spot.

Audio recordings were evaluated. Mars is a silent spot.

Not particularly friendly to people, but quiet: Mars.

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An international team of researchers has evaluated audio recordings from Mars for the first time. The result: silence reigned on the Red Planet. However, there are two different speeds of sound.

Mars would be a good place to rest for those who need a rest: “There are only a few natural sources of sound, except for wind,” scientists explained on the occasion of the publication of their study in the journal Nature on Friday. However, the five-hour audio recordings came as a surprise: There are two different speeds of sound on Mars.

The recordings come from two microphones of NASA’s “Perseverance” rover, which landed on Mars in February last year. Now they have been evaluated for the first time by a research team led by lead author Sylvester Morris.

There was such a silence on the recordings that scientists began to fear something was wrong with the measurements. But then something can be heard, for example the hum of the rotor blades of the tiny, ultra-lightweight helicopter “Ingenuity” of the NASA rover.

It will be difficult to have conversations

Through their studies, scientists were able for the first time to prove that the speed of sound on Mars is 240 meters per second, that is, slower than the speed of sound on Earth, where sound travels at a speed of 340 meters per second. This was expected because Mars’ atmosphere is 95% carbon dioxide and about 100 times thinner than Earth’s.

Surprisingly, however, the sound produced by the laser traveled at 250 meters per second – faster than expected. “I panicked a little,” lead author Morris said. “I told myself that one of the two scales must be wrong because there is only one speed of sound on Earth.”

There are two speeds of sound on Mars: one for high-pitched sounds, such as lasers, and one for low frequencies, such as the hum of a helicopter. “All these factors will make it difficult for two people who are only five meters apart to hold a conversation,” said the French research institute CNRS.