Sound Travels Much Slower on Mars, Researchers Find (cbsnews.com) 52
"For 50 years, interplanetary probes have returned thousands of striking images of the surface of Mars, but never a single sound." So says the largest fundamental science agency in Europe, the French National Centre for Scientific Research (France's state research organisation).
Then they made a surprising discovery, reports CBS News: Researchers studying recordings made by microphones on NASA's Perseverance rover found that sound travels much slower on Mars than it does on Earth... In addition, the researchers realized that there are two speeds of sound on Mars — one for high-pitched sounds and one for low-pitched sounds. This would "make it difficult for two people standing only five meters apart to have a conversation," according to a press release on the findings.
The unique sound environment is due to the incredibly low atmospheric surface pressure. Mars' pressure is 170 times lower than Earth's pressure. For example, if a high-pitched sound travels 213 feet on Earth, it will travel just 26 feet on Mars.
While sounds on Mars can be heard by human ears, they are incredibly soft. "At some point, we thought the microphone was broken, it was so quiet," said Sylvestre Maurice, an astrophysicist at the University of Toulouse in France and lead author of the study, according to NASA. Besides the wind, "natural sound sources are rare," the press release said.
But NASA scientists think Mars may become more noisy in the autumn months, when there is higher atmospheric pressure. "We are entering a high-pressure season," co-author of the study Baptiste Chide said in the press release. "Maybe the acoustic environment on Mars will be less quiet than it was when we landed."
Then they made a surprising discovery, reports CBS News: Researchers studying recordings made by microphones on NASA's Perseverance rover found that sound travels much slower on Mars than it does on Earth... In addition, the researchers realized that there are two speeds of sound on Mars — one for high-pitched sounds and one for low-pitched sounds. This would "make it difficult for two people standing only five meters apart to have a conversation," according to a press release on the findings.
The unique sound environment is due to the incredibly low atmospheric surface pressure. Mars' pressure is 170 times lower than Earth's pressure. For example, if a high-pitched sound travels 213 feet on Earth, it will travel just 26 feet on Mars.
While sounds on Mars can be heard by human ears, they are incredibly soft. "At some point, we thought the microphone was broken, it was so quiet," said Sylvestre Maurice, an astrophysicist at the University of Toulouse in France and lead author of the study, according to NASA. Besides the wind, "natural sound sources are rare," the press release said.
But NASA scientists think Mars may become more noisy in the autumn months, when there is higher atmospheric pressure. "We are entering a high-pressure season," co-author of the study Baptiste Chide said in the press release. "Maybe the acoustic environment on Mars will be less quiet than it was when we landed."
Difficult to have a conversation (Score:3)
When you're gasping for air.
This is news? (Score:2)
Wait till they get to the moon!
Or the upper atmosphere of earth . Or under water.
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The speed of sound underwater is about 3300 mph, almost five times faster than in air. This leads to some problems while scuba diving, trying to determine what direction something is located or how far away it is. It was especially troublesome when diving in shallow water where there was also boat traffic. You would be certain a boat was coming directly toward you, ignoring your dive flag. When the sound got so loud and so close but you still couldn't see any surface traffic, you would counterintuitivel
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In related news ... (Score:2)
The unique sound environment is due to the incredibly low atmospheric surface pressure. Mars' pressure is 170 times lower than Earth's pressure. For example, if a high-pitched sound travels 213 feet on Earth, it will travel just 26 feet on Mars.
NASA adds data point for Alien [wikipedia.org] premise that, "In space no can hear you scream" ...
In related, related news, this has already been experimentally confirmed here on Earth, Confirmed: In space no one can hear you scream [phys.org]
The old tagline "in space no one can hear you scream" has been confirmed by a South African mother loudly shouting for her children to tidy their room from 33,000 meters above the ground. Or not so loudly, as the case appears to be.
The experiment, carried out by a graduate engineer from Brunel University London and the BBC Radio show "The Naked Scientists," involved sending a microphone and speaker on a custom-built Screaming Satellite to near-space to test how high-up the scream could still be heard.
Science suggests that as the payload's altitude increases—and the air becomes correspondingly thinner—the level of the sound picked up by the microphone should decrease.
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The unique sound environment is due to the incredibly low atmospheric surface pressure. Mars' pressure is 170 times lower than Earth's pressure. For example, if a high-pitched sound travels 213 feet on Earth, it will travel just 26 feet on Mars.
This needed "research"? I'm sure any 19th century physicist could have told you that.
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The old tagline "in space no one can hear you scream" has been confirmed by a South African mother loudly shouting for her children to tidy their room from 33,000 meters above the ground.
I've got news for you - two people, both at ground level, who are 33000 meters apart cannot hear each other scream either.
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I've got news for you - two people, both at ground level, who are 33000 meters apart cannot hear each other scream either.
The article could be written more clearly. The experiment was conducted at 33km up, but was between a speaker and microphone *on* the rig.
To ensure that the sound vibrations coming out of the speaker were not simply transferred to the microphone through the polystyrene box containing the device, a rig had to be devised specially by science exhibition-builder Dave Ansell, a regular on The Naked Scientists, to isolate the two devices between sets of springs.
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We might can't hear them scream...but can we at least still enjoy watching them scream? ;-)
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In space no one can hear you scream
This is just confident ignorance spewed from the Dunning-Kruger Peak.
In space, usually nobody hears you scream, but sound is carried by vibrations in a gas, and in a near-vacuum released gasses expand. And of importance here, a scream is not merely conveyed by gasses; in that case, the claim would be true. For example, nobody can hear your boom-box in space. But a scream? A scream provides it's own gasses! If you're on a space-walk and you start screaming and then remove your helmet, people inside the ship
Re: In related news ... (Score:1)
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In your moronic link, the experiment was actually "can you hear shit on earth from 33km away." Neither the surface of the Earth nor the balloon were "in space."
No need to be ugly... The article could be written more clearly. The experiment was conducted at 33km up, but was between a speaker and microphone *on* the rig.
To ensure that the sound vibrations coming out of the speaker were not simply transferred to the microphone through the polystyrene box containing the device, a rig had to be devised specially by science exhibition-builder Dave Ansell, a regular on The Naked Scientists, to isolate the two devices between sets of springs.
This isn't news.... (Score:3)
Speed of sound is directly related to atmospheric pressure. This has been known for decades.
Pretty sure we had this conversation in high school physics class discussing speed of sound on Earth, Mars, and Jupiter. FYI, in case someone wants a news scoop, the speed of sound in Jupiter's atmosphere is ridiculous as get closer to the center of the planet.
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Re:This isn't news.... (Score:4, Insightful)
It's not even about pressure. Martian atmosphere is mostly cold carbon dioxide. Its mean molecular velocity will be significantly lower than the warmer nitrogen on Earth.
Yes temperature is important too because of the density of the gas.
Density is what matters. That's also why it is so much faster underwater, and even faster still in a metal rod.
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However according to the Newton-Laplace equation, if you just increase the density of a gas, while leaving everything the same, then the speed of sound though that gas would be reduced.
The speed of sound through a gas increases with the root of the division of bulk modulus of the material (a measure for stiffness/compressability) over density. The bulk modulus is dependent on pressure, which again is dependent on temperature. Thus GP was quite correct.
Sound is faster under water m
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It's not even about pressure. Martian atmosphere is mostly cold carbon dioxide. Its mean molecular velocity will be significantly lower than the warmer nitrogen on Earth.
Yes temperature is important too because of the density of the gas.
Density is what matters. That's also why it is so much faster underwater, and even faster still in a metal rod.
Density and compressibility (adiabatic or otherwise), for the simplest model. And sound speed is /inversely/ proportional to the sqrt of density. So you're right: it matters, but in exactly the opposite way you claim.
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It's not even about pressure.... mean molecular velocity will be significantly lower...
That is literally the definition of temperature.
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It's not even about pressure.... mean molecular velocity will be significantly lower...
That is literally the definition of temperature.
...and there I go posting without sufficiently previewing. Comment editing sure would be a nice feature on a platform like this in 2022...
Anyways, I was gonna say some stuff about the relationship between pressure and temperature, and how mean molecular velocity is a key attribute of both, but the moment has now passed. So it goes.
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Speed of sound is directly related to atmospheric pressure. This has been known for decades.
Speed of sound in an ideal gas equals the square root of (gamma RT/m), where gamma is the ratio of specific heats, R is the ideal gas constant, T is the (absolute) temperature, and m is the molecular mass.
For carbon dioxide, the ratio of specific heat is a strong function of temperature (since as a triatomic molecule, it has a lot of internal degrees of freedom). Not a strong function of pressure.
Isn't this obvious? (Score:2)
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Yes, we already knew this. Recent studies have definitively confirmed that Slashdot dupes [slashdot.org] travel more slowly on Mars.
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Hey, at least they didn't claim the speed of light is slow on mars.
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Hey, at least they didn't claim the speed of light is slow on mars.
So people can still appear bright, and if you can't hear them you will never know any better.
The Numbers Add Up (Score:2)
Yes, we already knew this. Recent studies have definitively confirmed that Slashdot dupes [slashdot.org] travel more slowly on Mars.
March 24th? Note that just as a Mars echo takes longer to occur, the Mars dupe also appears later than the common dupe.
Re: Isn't this obvious? (Score:1)
Temperature and molecular weight, NOT density. (Score:2)
Don't we already know that the speed of sound is determined by the density of the medium?
The speed of sound in a gas is essenaially an aggregate of the speed of the brownian motion of the molecules. The temperature is proportional to the energy per molecule so (for an ideal gas) a molecule's velocity is proportional to the square root of the temperature divided by the molecular weight.
The pressure does not affect the speed of sound at all - a given mix of gasses will have the same speed of sound at a given
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a molecule's velocity is proportional to the square root of the temperature divided by the molecular weight.
square root of the quantity (temperature divided by molecular weight), i.e. ... sqrt (T / m)
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OK, that makes sense. But presumably they already knew that CO2 was dispersive across the frequency range they were testing so it still shouldn't be that big of a surprise to observe a speed-frequency effect. Not criticsing, just observing that they probably got what they were expecting.
BTW, I assume from your sig that the four-note song produced by Bantam Dominique roosters is in the same sequence as Happy Birthday, correct?
Happy birthday bird. (offtopic) (Score:2)
BTW, I assume from your sig that the four-note song produced by Bantam Dominique roosters is in the same sequence as Happy Birthday, correct?
Correct. Exactly the same timing, tone, and emphasis. (I tried to describe it but couldn't get it past the lameness filter.) Most of our bantam doms did it that way, and it's also a common crow pattern among American Game Bantams.
We did have one that did a three-note call - exactly the pitch, emphasis, and timing of the instrumental third through sixth notes of the
No testing on Earth? (Score:2)
Did nobody (especially NASA) not ever test this on Earth in a low vacuum with a Mars-like atmosphere? Did they launch the mic without testing it?
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Did nobody (especially NASA) not ever test this on Earth in a low vacuum with a Mars-like atmosphere? Did they launch the mic without testing it?
Someone did, sort of: Confirmed: In space no one can hear you scream [phys.org]
The old tagline "in space no one can hear you scream" has been confirmed by a South African mother loudly shouting for her children to tidy their room from 33,000 meters above the ground. Or not so loudly, as the case appears to be.
The experiment, carried out by a graduate engineer from Brunel University London and the BBC Radio show "The Naked Scientists," involved sending a microphone and speaker on a custom-built Screaming Satellite to near-space to test how high-up the scream could still be heard.
Science suggests that as the payload's altitude increases—and the air becomes correspondingly thinner—the level of the sound picked up by the microphone should decrease.
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Seems that guy didn’t test frequency ranges or even do a very scientific experiment. My question is why NASA didn’t bother to do testing of the mic in a Mars-like atmospheric simulation. I mean it seems like a very obvious thi bc to do. They tested true Mars helicopter that way.
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Why would you "test" those things when there is a solid theoretical understanding going back hundreds of years?
You calculate what you need, then you test the engineering in the part of the range where it is easiest to get accurate readings to make sure the device works as intended.
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Uh, yeah you test the engineering. And since they were surprised by this result, it shows that they were overconfident in their modeling. Like does the mic work in a low vacuum. You know the rover budget is millions of dollars right? They can’t bother to turn on the mic for a few minutes when testing the rover .. assuming they even bothered to test the rover .. after all it can all be calculated. No need for control experiments.
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Nobody was surprised by the result. You made the insane presumption that the grammar of the clickbait was meaningful.
The only thing even close to surprise described in the article is when they thought maybe the mic was broken, because it was picking up so little sound. And that has nothing to do with the engineering, it is just a technician figuring out the gain for the headset.
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Ok, you're correct it was clickbait. I just saw the paper in Nature I didn't click on before which states it followed the theoretical models.
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Who cares! (Score:1)
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You also have to listen for approaching Elon's in order to get your B.S. guard up in time.
sound on Jupiter (Score:2)
"On Mars, few people can hear you scream" (Score:2)
Nah, it loses something when used that way. lol ;)
Old news (Score:2)
a=sqrt(gamma*R*T)
Sound slow (Score:2)
Sound may be slow on Mars, but journalists are slow on earth.