For the first time, the speed of sound on Mars has been measured, and it differs significantly from that on Earth. The Perseverance Mars rover is equipped with microphones and lasers, which have been used to detect the speed of sound in its surroundings. Of course, some may assume that this is all a ruse to allow science fiction fanatics in charge of the rover to fire lasers on another planet and make the closest thing to pew sounds. For the last 50 years, cameras aboard spacecraft have allowed us to glimpse other planets, sometimes at wavelengths of light that are beyond the human eye’s ability to see. Perseverance, on the other hand, is the first to include microphones, giving us a new way to explore another universe.
Apart from Titan, Mars is the only location our probes have gone where a microphone would be useful because no one can hear you scream or make any other noise in space. Perseverance also has lasers that it can use to vaporize adjacent rocks. Dr. Baptiste Chide of the Los Alamos National Laboratory discussed combining the two pieces of equipment to detect the delay as the sound from the laser hitting rocks was picked up by a microphone at the 53rd Lunar and Planetary Science Conference. The local speed of sound might then be calculated by dividing the distance traveled by the delay by the distance traveled by the delay.
Although the speed of sound in Earth’s atmosphere is commonly said to be 343 m/s, this is only true under certain circumstances. Because the speed of sound in air varies with temperature and the stiffness of the conducting material, there is no one sound speed on Mars or Earth. Nonetheless, the research demonstrates the pace of Jezero Crater under a number of circumstances. That speed was usually approximately 240 m/s (540 mph).
The findings were obtained by firing 30 laser bursts at target sites during a 10-second period, with 5-10 of those bursts aimed at areas a few millimeters apart. The shock wave formed by the plasma emitted by the lasers hitting the Martian rocks produced a high-frequency sound. The daylight Martian temperature decreases by an incredible 40 degrees Kelvin (72 degrees F) between ground level and 2 meters (6.6 feet) above the surface, according to a property of the Martian atmosphere mentioned in the conference presentation.
That results in a 10% change in sound speed, providing some incredible audio phenomena if anybody could hear them, as well as a reversal of how sound may be focused while traveling over water. Because the microphone is at 2.1 meters and the rocks are, by definition, at ground level, the sound captured was an average of the heights in between, rather than a single altitude.
The writers also mention “The Mars idiosyncrasy,” which refers to the fact that carbon dioxide at low pressure has certain peculiar acoustic properties. CO2 molecules can’t relax their vibrational modes once a peak has passed at 240 Hz (just below a piano’s middle C), hence sounds above this frequency move 10 m/s quicker than those below it.
According to the conference report, “it may create a distinct listening experience on Mars with an early entrance of high-pitched sounds relative to bass.” This would only be observable on Mars, the sole planet in the Solar System. More study will be done to discover how speed varies throughout the course of a Martian year, as well as during one of the planet’s legendary dust storms.
