The density of the Martian atmosphere is 1% of that of the planet we live on. This means that the sound wave is very weak compared to what we know. This is also what comes out of the two microphones installed on the Preserver's SUV
Seemingly a banal question. We will walk around on the surface of Mars without a spacesuit and try to listen to the whispers of the wind. What does it sound like? Although Mars has an atmosphere, it is very thin compared to Earth's: its density is 1% of that of the planet we live on. This means that the sound transmission is very weak compared to what we know, which means that the voices will be much weaker than what we are familiar with. On the red Perseverance SUV, two microphones were installed, one on the top and one in the belly. From the moment these two devices were activated, the sounds of the wind were heard, but their intensity was weak.
On Earth, the speed of sound waves is 343 meters per second at a temperature of 20 degrees Celsius at sea level, in water the speed is 1430 meters per second and in metal 5.1 km per second. The higher the density of the material, the faster the sound travels. The density of the Earth's atmosphere is 1.2 kg /m0.02 and that of Mars 12 kg/mXNUMX. These numbers clearly show how sound travels in the atmosphere Mars is relatively weak. As you go up, the density of the atmosphere decreases. This rule applies to any planet or moon with a particularly thin atmosphere, for example, the transmission of sound is negligible.
On Mars there is a phenomenon that is unknown on Earth. The content of the Martian atmosphere is carbon dioxide, and with the onset of winter the temperature drops below the freezing point of carbon dioxide and it begins to cool until it freezes and accumulates on the ground, especially at the poles, and turns into dry ice. In the summer it thaws and in the process of sublimation returns to the atmosphere. This means that with the onset of winter, the density of the atmosphere decreases and, as a result, the sound conduction in the atmosphere also decreases. A reverse process occurs with the onset of summer. The carbon dioxide evaporates and the atmosphere becomes denser. We have a seasonal process of increasing sound conduction in the summer and weakening it in the winter. For the sake of illustration, if we walk outside in the crimson winter (assuming we survive its extreme conditions) and were and will be equipped with headphones, we will have to raise the volume in order to hear our surroundings and in the summer we will turn it down.
There are very low places on Mars where sound travels a little differently than average. Let's take Hellas Crater for example. It is a huge crater, 2400 km in diameter and 9 km deep. The average atmospheric pressure of Mars is 7 millibars. The atmospheric pressure at the bottom of this crater is 12.5 millibars, which is almost 2 times. This means that the sound velocity is higher in this place than in the open plains of Mars.
In future studies of Mars, it will be possible to weave its soil with a web of loudspeakers and to hold balloons with loudspeakers in the atmosphere and to test the behavior of sound waves on a global scale.
It is also possible to do simulations in laboratory conditions regarding other bodies in laboratory conditions. For example, take an empty chamber, install speakers in it and make sounds at a power of, for example, 50 decibels and fill it with nitrogen at a pressure of 1.6 atmospheres, like Titan's atmosphere, and see what happens. Since Titan's atmosphere is denser than Earth's, sound transmission is stronger. What ours sounds like 50 decibels on Titan can sound like 70 decibels (the numbers I present are just a guess). The atmospheric pressure on Venus is 90 atmospheres, so the sound transmission there will be even greater. From the point of view of the person, every beep can be heard as deafening.
Another factor to consider is dust storms on Mars. It often happens that there are storms on a global scale. Such a case occurred when Mariner 9 entered orbit around Mars in 1969. The intensity of the dust storm was such that for 3 months it was impossible to operate the spacecraft's research instruments until the storm subsided and all the dust settled to the ground. Such storms increase the air density not only because of the atmospheric components, but because of the dust. As the density increases, the sound conduction also increases as more dust accumulates in the atmosphere, and it decreases with the weakening of the storm and the settling of the dust to the ground. A topic worthy of research. Defining the subject - Seasonal changes in sound transmission in the Martian atmosphere following the occurrence of dust storms.
Another way to study sound transmission in the atmosphere of Mars is to place recording devices on balloons and raise them to heights in the Earth's atmosphere where the atmospheric pressure is the same as that prevailing on the surface of Mars, and to compare the measurements with the recordings made by the Mars ground vehicle, Perseverance. It is possible that in the future it will be possible to place balloons in the Martian atmosphere for this purpose.
Another topic worthy of research is micro meteoroids that enter the earth's atmosphere, during this penetration they ignite and burn. It is likely that during their movement they encounter other meteorites that also get hot and burn. It is possible that the collisions create any noise. On the ground it is impossible to hear it because the distance is too great, but it is possible that such noise, if it does exist, will be picked up by recording devices that will be placed on balloons that will travel at these heights.
Intrusion of micro meteorites into the Martian atmosphere also exists. It will be possible to measure these noises using balloons that will travel in the Martian atmosphere. These findings can be compared with the corresponding national findings.
The study of sound in different planetary environments opens the door to a completely new and extremely fascinating type of research.
More of the topic in Hayadan:
One response
Wait, so if the pressure on Mars is so low, our blood won't boil without a pressure suit?