NASA’s Mars Perseverance rover has discovered that sound travels much slower on the Red Planet than on Earth and behaves in unexpected ways that could have strange consequences for communication on the planet.
Sound waves travel slower through March‘atmosphere than they do on Earth. This makes sense, because the speed of sound depends on the density of the material the sound waves are passing through (and, additionally, on some other variables, including temperature). In earth’s atmosphereat 68 degrees Fahrenheit (20 degrees Celsius), sound travels at 1,125 feet (343 meters) per second, but in the much denser medium of water, it travels at 4,856 feet per second (1,480 m /s), according to Scientific alert.
Mars’ barely there atmosphere is more than 100 times thinner than Earth’s, so sound travels much slower through it, traveling at just 787 feet per second (240 m/s), according to ScienceAlert.
But NASA Perseverance rover, which landed on the red planet in February 2021, discovered oddities in sound on Mars that scientists did not expect, according to a new study presented at the 53rd Conference on Lunar and Planetary Sciences earlier this this month.
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Measurements made by a team of scientists at Los Alamos National Laboratory, a US Department of Energy facility in New Mexico, using a microphone on Perseverance’s SuperCam instrument revealed that high-pitched sound spreads faster on Mars than low notes, which it didn’t. t been observed anywhere else.
Scientists say this strange behavior could be explained by thermal fluctuations in the first 10 kilometers of Mars’ atmosphere above the planet’s surface. During the day, as the sun’s rays hit and heat the Martian rock, convective air currents and turbulence stir up this layer of Martian air, also known as the planetary boundary layer. This changes the behavior of carbon dioxide molecules. Atmosphere of Mars contains 96% carbon dioxide, but the atmospheric pressure is very low. (For comparison, Earth’s much denser atmosphere contains only 0.041% carbon dioxide.)
“Due to the unique properties of low-pressure carbon dioxide molecules, Mars is the only Earth-planet atmosphere in the Solar System that experiences a change in the speed of sound right in the middle of the audible bandwidth (20 Hertz to 20,000 Hertz) , ” write the researchers in a paper presented at the conference.
At frequencies above 240 Hertz, “the collision-activated vibrational modes of carbon dioxide molecules do not have enough time to relax or return to their original state,” the researchers said, which translates by sound waves at higher frequencies traveling over 32 feet. per second (10 m/s) faster than low frequencies.
This means that if you were standing on Mars listening to distant music, you would hear higher pitches before hearing lower pitches.
The team plans to continue using data from the SuperCam microphone to observe how things like daily and seasonal variations can affect the speed of sound on Mars. They also plan to compare acoustic temperature readings to readings from other instruments to try to understand large fluctuations, according to the statement in Science Alert.
The paper to be found on the conference website.
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