After the Perseverance rover landed on Mars in February of last year, its two microphones began recording, allowing scientists to hear what our “neighboring planet” is “saying.”
In a study published in the journal Nature, NASA researchers presented their initial analysis of the sounds captured on the Red Planet.
Sylvestre Maurice, the lead author of the study and co-scientific director of SuperCam, a shoebox-sized instrument mounted on the mast holding the main microphone, stated that the sounds revealed previously unknown disturbances on Mars.
Since landing on Mars over a year ago, NASA’s Perseverance rover has been using its microphone to record sounds on the Red Planet. These recordings have helped scientists discover that the speed of sound on Mars differs from that on Earth, according to AFP.
The research team used data from the microphone to measure the speed of sound on Mars. Specifically, they measured the time it took for the sound emitted from Perseverance’s laser firing to return to the rover’s microphone. The rover fires lasers at rocks to analyze their composition.
This study confirmed for the first time that sound on Mars travels slower than on Earth, at a speed of 240 meters per second compared to 340 meters per second on Earth.
However, this research also revealed another issue on Mars: different sound frequencies travel at different speeds. Sounds from helicopter blades or natural sounds with lower frequencies travel at the previously mentioned speed, but higher frequency sounds, such as those from Perseverance’s laser, travel at 250 meters per second, which is 10 meters per second faster.
“I was a bit shocked,” Maurice said. “I told myself that one of the two measurements must be wrong because on Earth, you only have one speed of sound.”
The reason for this phenomenon is hypothesized to be due to Mars’ atmosphere, which is composed of 95% carbon dioxide, while on Earth it is only 0.04%. Additionally, Mars’ atmosphere is about 100 times thinner than Earth’s, making sounds weaker by 20 decibels, which affects the speed of sound.
They discovered that there are two sound speeds on the surface of Mars: one for high-intensity sounds, like laser noises, and another for lower frequencies, like the humming of helicopter blades. The microphone also helps measure the surface temperature around the rover. This is because sound travels at different speeds depending on temperature. By measuring the speed of sound each time Perseverance fires its laser, researchers can quickly calculate temperature changes. The research team plans to continue monitoring and analyzing Martian sounds for a year to learn more about changes under different conditions on the Red Planet, such as during winter or dust storms.
This means that human ears will hear high-frequency sounds slightly earlier.
“On Earth, the sound of an orchestra reaches your ears at the same speed, regardless of whether they are low or high sounds. But imagine on Mars, if you move away from the stage a bit, you would perceive the sound reaching your ears as somewhat chaotic, as high-frequency sounds arrive first, while lower frequency sounds reach your ears later,” Maurice explained.
Dr. Thiery Fouchet from the Paris Observatory, a member of the research team, stated that studying sound propagation on Mars and listening for background noise like wind disturbances will allow them to refine numerical models to predict climate and weather on the Red Planet.
Sound on Mars also travels shorter distances due to the planet’s thin atmosphere. On Earth, sound slows down at a distance of 65 meters, while on Mars, that distance is only 4 meters. This means that a few meters can be quite far if we were to converse on this planet. NASA has also released the recorded sounds for people to gain a new perspective on the Red Planet.
Billions of years ago, Mars had a thick atmosphere rich in carbon, with lakes and oceans formed from liquid water, and there may have even been fine clouds floating in the sky. At that time, the sun was much smaller than it is today, and the light was weaker, but when solar storms occurred, their strength was much greater than today.
The size of Mars is smaller than that of Earth, meaning it cools down much faster than Earth – Earth’s core remains molten – the continuously rotating iron core still generates a strong magnetic field, which can deflect solar winds and prevent them from impacting us.
After Mars cooled down, its core solidified, and the planet’s magnetic field gradually disappeared. After about 100 million years, solar winds stripped away Mars’ atmosphere. The air pressure on Mars dropped to near vacuum levels, surface oceans gradually boiled away, and eventually, the entire planet became extremely arid.
In other words, the solar system today is much more habitable than it was 3 billion years ago. Yet, Mars remains lifeless and devoid of life.
