NASA’s Perseverance Mars rover has found that sound travels much slower and more unexpectedly on the red planet than on Earth.

An international team of scientists first analyzed audio recordings Tuesday. Result: On the red planet, be quietIt was broken only by the occasional gust of wind.

“There are only a few natural sources other than wind,” the scientists explained when their study was published in the journal Nature. However, the five-hour sound recordings came as a surprise: Mars has two different speeds of sound.

NASA’s Perseverance rover records sounds on Mars

The recordings came from two microphones on NASA’s “Perseverance” Mars rover, which landed on Mars in February last year. They are now being analyzed for the first time by a team of researchers around the main author. Maurice Sylvester.

The recordings were very quiet, and scientists feared something was wrong with the measurements. But some could hear, for example, the roar of the “ingenuity” rotor blades on NASA’s ultralight mini-shuttle.

The speed of sound is slower than that of the earth

Through their study, scientists were able to prove for the first time that the speed of sound on Mars is 240 meters per second, less than on Earth, where sound travels at 340 meters per second. This was expected as the atmosphere of Mars was formed 95% carbon dioxide and 100 times more sensitive than Earth.

However, the laser-generated sound travels at a speed of 250 meters per second faster than expected. “I’m kind of panicked,” reports lead author Maurice. “I told myself that one of the two measurements must be wrong because there is only one speed of sound on earth,” he added.

Different sound velocities for higher and lower frequencies

So Mars has two speeds of sound: one for high-pitched sounds like lasers and one for low frequencies like the hum of helicopter rotors.

“All of these factors make it difficult for two people to communicate just five meters apart.”CNRS, a French research institute, explains.