The first audio recordings on Mars reveal a quiet planet with occasional gusts where two different sound speeds would have an oddly delayed effect on hearing, scientists said Friday.
After NASA’s Perseverance rover landed on Mars last February, two microphones began recording, giving scientists the first opportunity to hear what it’s like on the Red Planet.
In a study published Friday in the journal Nature, the scientists gave their first analysis of the five hours of sound picked up by Perseverance’s microphones.
The audio revealed previously unknown turbulence on Mars, said Sylvestre Maurice, the study’s lead author and co-scientific co-director of the shoebox-sized SuperCam mounted on the rover’s mast and containing the main microphone.
The international team listened to flights from the small Ingenuity helicopter, a sister vessel to Perseverance, and heard the rover’s laser zap rocks to study their chemical makeup — making a “click-clack” sound, Maurice told AFP.
“We had a very localized sound source, between two and five meters (six to 16 meters) from the target, and we knew exactly when it was going to fire,” he said.
The study confirmed for the first time that the speed of sound on Mars is slower, traveling at 240 meters per second, compared to Earth’s 340 meters per second.
This was expected because Mars’ atmosphere is 95 percent carbon dioxide — compared to Earth’s 0.04 percent — and is about 100 times thinner, making the sound 20 decibels weaker, the study said.
But the scientists were surprised when the laser’s sound hit 250 meters per second — 10 meters faster than expected.
“I panicked a little,” Maurice said. “I told myself that one of the two measurements was wrong, because on Earth you only have one speed of sound.”
They had discovered that there are two speeds of sound on the surface of Mars: one for high frequencies, such as the laser’s zap, and another for lower frequencies, such as the hum of a helicopter’s rotor.
This means that human ears would hear high-pitched sounds a little earlier.
“On Earth, the sounds of an orchestra reach you at the same speed, whether they are low or high. But imagine on Mars, if you are a little far from the stage, there will be a big delay,” Maurice said.
“All of these factors would make it difficult for two people to have a conversation just five meters (16 feet) apart,” France’s research institute CNRS said in a statement.
‘Scientific guess’ pays off
It was otherwise so quiet on Mars that scientists repeatedly feared something was wrong, the CNRS said, possibly evoking memories of two failed previous attempts in 1999 and 2008 to record sound there.
“There are few natural sources of sound, except for the wind,” the scientists said in a statement linked to the study.
The microphones picked up numerous “screeches” and “clank” sounds as the rover’s metal wheels interacted with rocks, the study said.
The recording can also warn of problems with the rover, such as how drivers sense something is wrong when their car starts making strange noises.
Maurice said he thought the “scientific gamble” to bring microphones to Mars was a success.
Thierry Fouchet of the Paris Observatory, who was also involved in the study, said listening for turbulence, such as vertical winds known as convection plumes, “will allow us to refine our numerical models for forecasting climate and weather.” “.
Future missions to Venus or Saturn’s moon Titan can now also be equipped with microphones.
And Perseverance is far from done with eavesdropping. While its core mission will last just over two years, it could remain operational for much longer — the Curiosity rover kicks off another nine years in a planned two-year period.
(This story was not edited by DailyExpertNews staff and was generated automatically from a syndicated feed.)