Question about sound in space.

[piplipa]

Hey guys, I'm brand new to the forums, bear with me.
I have a few recordings that were taken in space, and I was wondering if sound is distorted or goes fast or slower when out of the atmosphere, sort of like it does under water.

I would appreciate honest, educated answers. I am working on a project for NASA at the moment.
Thanks,

-Alex

 

[3488]

Welcome to SDC Alex.

There is no sound in space. There is no medium for sound waves to travel through. On bodies with no atmosphere, like Mercury or the Moon, it is silent. Mars may have a little, but sound waves may not travel well in that pathetically thin atmosphere, approx same density as Earth's is at 35 KM above sea level.

Andrew Brown.

 

[MeteorWayne]

Andrew is absolutely correct. There is no sound in space.

If you have heard recordings, they are electromagnetic signals (which can not be heard) converted into sound. That is often done because sound is our most discriminating sense.

What NASA project are you working on?

Welcome to Space.com.

 

[Yuri_Armstrong]

Sound needs a medium to travel through. Since space is mostly a vacuum there probably is a very minute amount of sound but it's so tiny that we can't detect it. Similar to the microgravity on the ISS I'd say. As Andrew said planets with thin atmospheres will be quieter.

 

[a_lost_packet_]

Hey guys, I'm brand new to the forums, bear with me.
I have a few recordings that were taken in space, and I was wondering if sound is distorted or goes fast or slower when out of the atmosphere, sort of like it does under water.

I would appreciate honest, educated answers. I am working on a project for NASA at the moment.
Thanks,

-Alex

Sound is communicated by vibrations.

Vibrations occur in a medium.

There is no suitable medium in space by which acoustic vibrations (sound) can be transmitted.

A table transmits sounds because when you bang on the table, it vibrates. If you press your ear against the table and hit it with your hand, you'll hear a very loud sound. That's because there are lots of molecules packed closely together - They transmit vibrations very easily.

Underwater, you can hear sounds very well. A tap on a piece of metal on the other side of the pool will easily be heard by most people when they are underwater. Even for those who have their heads above water, sometimes sounds are easily heard or even felt. That's because the water molecules are vibrating, transmitting those vibrations straight to their body, which vibrates in turn, passing those vibrations through to the ear.

Tapping yourself on the skull produces "sound" in the same way even though there aren't any vibrations of much consequence being transmitted through the air. The vibrations travel through your skull, straight to your ear.

Clapping your hands in air also creates vibrations in molecules. But, they're not as many of them and they aren't packed as densely as they would be in a table, water or even in your skeleton. So, if you stood 100 feet away and clapped your hands, someone could probably hear them. But, if they set their ear against a table and you used the same amount of force to hit that table, they'd hear that much better because the molecules being packed so much more closely together in the table end up transmitting the vibrations much more easily and rapidly than the air does.

In the movies, and sometimes in real life, a character will put their ear to the ground to listen for cavalry, tanks, trains, etc.. They do this because the ground can sometimes transmit sound much better than air - The molecules are closer together so they don't have as far to move in order to get other molecules to vibrate as well. (Just be careful trying to listen for trains and cars using that method.. you might get run over before you get a chance to figure out what direction their coming from.)

In space, there simply aren't many molecules available to vibrate. There are a few hydrogen atoms (or occasionally others) per cubic centimeter. That is much, much, less dense than even our atmosphere. It is certainly less dense than water, a table or our own skulls. In fact, space is so much more empty than anything else it's the closest approximation of a natural vacuum that we know of. Because of that, there is nothing there to react to vibrations and nothing there to transmit vibrations. There's really not enough "stuff" in space to vibrate in response to acoustic vibrations.

If you could hear sounds in space with your ears, it would mean there was some sort of medium there that transmitted physical, acoustic vibrations. If there was such a medium, the Earth would have tremendous difficulty going around the Sun and we'd be subjected to an extremely strong "wind" coming from space as we moved through it. Thankfully, there is no such medium in space.

So, you can't hear any sound in space simply because there's nothing there to vibrate.

 

[kg]

Perhaps Alex has been tasked with editing footage of astronauts aboard the ISS, space shuttle, or Soyuz capsule ("recordings that were taken in space")?
If the sound in such recordings is odd could it be caused by different pressure or concentrations of gasses than we are used to here on earth?

 

[a_lost_packet_]

...If the sound in such recordings is odd could it be caused by different pressure or concentrations of gasses than we are used to here on earth?

Pressure differences or the presence of gases (like helium) in the mix that effect the vocal cords would be the only thing that could cause such an effect in that way. And, if pressure was different enough from Sea Level to make a marked impact on sound quality, I'm afraid the astronauts wouldn't be speaking for very long. AFAIK, everything is kept at normal atmospheric pressure and gas mix.

Breathing Easy on the ISS

A sample vid tour of the ISS by Astronaut Michael Barratt:

[youtube]http://www.youtube.com/watch?v=-1OTSbIzcwI[/youtube]

(Note: Astronaut's voices can be effected by their body's reaction to micro-gravity. Sinus problems, stuffiness, etc..)

 

[kg]

Thank you lost_packet,
I guess I was getting confused with the pure oxygen environment of the Apollo era space capsules and the oxygen/helium used by divers.

 

[MeteorWayne]

The point from the OP is, that in space, there are not enough molecules to transmit a pressure wave, so there is no sound.

 

[EarthlingX]

Easy to remember :
http://www.telegraph.co.uk : In space, no one can hear you bark.

[youtube]http://www.youtube.com/watch?v=hp30nXYOrdA[/youtube]

More barking :

[youtube]http://www.youtube.com/watch?v=3JKhqtcFK4w[/youtube]

 

[adrenalynn]

Thank you lost_packet,
I guess I was getting confused with the pure oxygen environment of the Apollo era space capsules and the oxygen/helium used by divers.

There's no good excuse for flying exotic diving gasses. The pressure in the capsule is, per-force, maintained. Exotics are used to lower the oxygen narcosis and increase bottom times and max depths. They're necessary under _high_ pressures, not low pressures. I've dove heliox and it does raise the voice formant pitches and give something of a slurred speech effect, especially if you're a little "narc'd". Trimixes are more common, though, and don't have nearly as much effect.

 

[neilsox]

Pressure waves, similar to sound propagate in space at much lower frequencies, and high attenuation. Sound inside the spacecraft is almost normal. Air pressure as low as 4 psi is desirable to reduce the probability of a blow out and reduce the violence of the blow out if one occurs. 4psi requires about 99% oxygen. Neil

 

[adrenalynn]

That would be a pressure-altitude in the neighborhood of 32,000ft.

 

[MeteorWayne]

Pressure waves, similar to sound propagate in space at much lower frequencies, and high attenuation. Sound inside the spacecraft is almost normal. Air pressure as low as 4 psi is desirable to reduce the probability of a blow out and reduce the violence of the blow out if one occurs. 4psi requires about 99% oxygen. Neil

Facts:

Several systems are currently used on board the ISS to maintain the spacecraft's atmosphere, which is similar to the Earth's. Normal air pressure on the ISS is 101.3 kPa (14.7 psi); the same as at sea level on Earth. An Earth-like atmosphere offers benefits for crew comfort, and is much safer than the alternative, a pure oxygen atmosphere, because of the increased risk of a fire such as that responsible for the deaths of the Apollo 1 crew. It is approximately 78% nitrogen and 21% oxygen just like down here.
That's why for EVA's, the astronauts must prebreath pure oxygen overnight, to purge the nitrogen from their blood. The EVA suits operate with pure oxygen at much lower pressure:

The suit's regulator and fans activate when the servicing umbilicals are removed and the suit reaches an internal pressure of 4.3 psi (30 kPa). A typical EMU can support an astronaut for 8½ hours, with 30 minutes of reserves in the case of primary life support failure. To perform an EVA from the shuttle the cabin pressure is reduced from 14.7 psi to 10.2 psi for 24 hours, then an astronaut must pre-breathe for 45 minutes. EVAs onboard the ISS, the astronaut must pre-breathe for about four hours.

 

[adrenalynn]

I like the idea that we pressurize it at an altitude above the "death zone", and pump it full of oxidizers, better. Seems more sensible.

 

[kg]

...The EVA suits operate with pure oxygen at much lower pressure:
The suit's regulator and fans activate when the servicing umbilicals are removed and the suit reaches an internal pressure of 4.3 psi (30 kPa)....

Does this lower pressure change sound within the suit? I don't recall astronauts sounding different while in their spacesuits, "One small step...". Also, does the lower pressure cause dryness to the lungs and throat?

 

[adrenalynn]

It would lower the volume. But those microphones are already tuned for that.

It would also make them short of breath. They're effectively climbing Mt. Everest. At 4.3 PSI, the pressure-altitude is about 9239 m. Mt. Everest is just under 8900m, I believe.

Which is something I observe when listening to EVA traffic - short burst of speech, the start of a pant, the squelch nails it, then another short burst of speech.

 

[Yuri_Armstrong]

Hey guys, I'm brand new to the forums, bear with me.
I have a few recordings that were taken in space,

This wouldn't happen to be those Voyager recording you were talking about would they?

 

[MrUniverse]

I like the idea that we pressurize it at an altitude above the "death zone", and pump it full of oxidizers, better. Seems more sensible.

oxidizers meaning O[sub]2[/sub]?
Are you being sarcastic? If not, then I would have to agree. Seems more sensible to me that a spacecraft be pressurized at the low pressure and same gas content as the spacesuits currently are. If the spacecraft were punctured by micrometeor, the crew could dawn spacesuits until the hole was patched without fear of nitrogen narcosis. They also wouldn't have to pre-breath to prepare for an EVA. EVA's could be done with little notice instead of needing to prepare for hours.

It seems to me that the capsule (or whatever the design) could be made to be lighter, since the hull would only have to be made to contain about a third of the pressure.

As I understand it, it wouldn't be a fire hazard because the partial pressure of the oxygen (the pressure that the oxygen contributes) in the craft would be the same as at sea level on Earth (3.0 psi). This is in contrast to the 14.7 psi of pure oxygen in the Apollo I capsule that resulted in the infamous fire. Of course I could be way off base.

 

[MeteorWayne]

There are a few reasons for the lower pressure in an EVA suit. One is less pressure differential between inside and outside, i.e. less likely to burst.

The other is flexability. A suit pressurized to 14.7 PSI, would be too stiff to do any work in.

 

[xXTheOneRavenXx]

I guess I have my own question in regards to this then. Of course sound can't exist without a medium. However, what about the gases, particles, etc... within a nebula? Couldn't sound be propigated through these mediums? Or on Io? According to this article CoRoT has an acoustic capability to measure the seismic waves from stars in deep space?

http://www.space.com/scienceastronomy/star-sound-waves-magnetic-cycle-100826.html

Using the CoRoT (COnvection ROtation and planetary Transits) satellite, the astronomers measured the star's acoustic fluctuations, which CoRoT detected as slight variations in light intensity. By analyzing the vibrations, the researchers were able to map out some key details of HD49933's magnetic activity cycle.

Or am I misinturpreting what the means by which they are measuring this "sound". Until I read this article, I too though sound required a medium. Then just now I though about the gases etc contained within a nebula.

 

[EarthlingX]

You mean something like this :

chandra.harvard.edu : Galactic Super-volcano in Action

For Release: August 18, 2010


Credit: X-ray (NASA/CXC/KIPAC/N. Werner, E. Million et al); Radio (NRAO/AUI/NSF/F. Owen)

A galactic "super-volcano" in the massive galaxy M87 is erupting and blasting gas outwards, as witnessed by NASA's Chandra X-ray Observatory and NSF's Very Large Array. The cosmic volcano is being driven by a giant black hole in the galaxy's center and preventing hundreds of millions of new stars from forming.

Astronomers studying this black hole and its effects have been struck by the remarkable similarities between it and a volcano in Iceland that made headlines earlier this year.

With Eyjafjallajokull, pockets of hot gas blasted through the surface of the lava, generating shock waves that can be seen passing through the grey smoke of the volcano. The hot gas then rises up in the atmosphere, dragging the dark ash with it. This process can be seen in a movie of the Eyjafjallajokull volcano where the shock waves propagating in the smoke are followed by the rise of dark ash clouds into the atmosphere.

[youtube]http://www.youtube.com/watch?v=oRm0fnWyklo[/youtube]

NASAtelevision | August 24, 2010

Earlier this year, a powerful volcano in Iceland erupted and caused havoc with air traffic around Europe. Elsewhere in the Universe, a similar galactic super volcano has been erupting for millions of years. This composite image from NASAs Chandra X-ray Observatory with radio data from the Very Large Array shows a cosmic volcano being driven by a black hole in the center of the M87 galaxy. This eruption is pumping energy into the black holes surroundings and preventing hundreds of millions of new stars from forming just as the volcano in Iceland caused disruptions in the Earth's atmosphere. The comparison between the black hole in M87 and the volcano in Iceland shows that even though astronomical phenomena occur in exotic settings and over huge scales, the physics can be very similar to events on Earth.

Check about 17s in the video :
[youtube]http://www.youtube.com/watch?v=zXBER2uwepc[/youtube]

freysi007 | April 20, 2010

Amazing footage of the Icelandic Volcano Eyjafjallajökull recorded by Ómar Ragnarsson. Mother nature is one powerful creature that shows it strength in this video. You can actually see the shock waves coming from the Volcano.

 

[adrenalynn]

which CoRoT detected as slight variations in light intensity.

Stretching the definition of "sound" a bit there... (emphasis mine)

You can map any shift in frequency over time to audio, since that's all sound is - a change in frequency over time. That doesn't mean that it started out being something a human could hear. Radio active decay can be mapped the same way - which is exactly what a Geiger counter/detector does.