Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: paul.fr on 18/05/2007 19:58:55
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Can sounds and smells travel in space?
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How many different answers do you want to this?
In a perfect vacuum, there can be neither sound nor smell; but since the nature of small is that it is created by trace amounts of chemicals, thus when you release these chemicals into a perfect vacuum, it then ceases to be a perfect vacuum.
If you are asking whether sounds and smell can travel within the mini-atmosphere of a spacecraft suitable for human habitation, then the answer is yes, since neither require gravity.
In real space, on the other hand, you do not have a perfect vacuum. In what we usually call space, the space surrounding the Earth, we are still in fact within the outer atmosphere of the Sun, and we are subject to shock waves comming from the Sun (these are technically not sound waves in the sense that we would regard speech to be composed of sound waves, but they are shock waves like you would have from an explosion). The atmosphere at this distance from the Sun (which is actually flowing past the Earth at supersonic speeds) is too rarefied to be compressible, and hence cannot transmit ordinary sound, but only shock waves that do not require compressibility of the gas that it is transmitted through.
As for whether you can detect smells in space - I would personally advise against trying to stick your nose outside the micro-environment of a spacecraft just to have a sniff of what is outside.
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How many different answers do you want to this?
how many do you have? [;)]
As for whether you can detect smells in space - I would personally advise against trying to stick your nose outside the micro-environment of a spacecraft just to have a sniff of what is outside.
Ok then, say we used an electronic nose. Would that detect any smells or odours?
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As for whether you can detect smells in space - I would personally advise against trying to stick your nose outside the micro-environment of a spacecraft just to have a sniff of what is outside.
Ok then, say we used an electronic nose. Would that detect any smells or odours?
The trouble is, what is an electronic nose?
There are chemicals (although very diffuse) in space, and there are ways of detecting those chemicals; but a smell is a particular biological response (one that involves an olfactory gland and a brain), and although it too is nothing more than a chemical detection device, it will have its own particular idiosyncrasies that might be very different to the particular strengths and weaknesses of your 'electronic nose'.
There is no doubt that we could build an 'electronic nose' that could detect 'smells' in space; but it is also very possible to build a different 'electronic nose' that could not detect anything meaningful is space - it all depends on how you fabricate your 'electronic nose' - but however it is, it will still be different from a biological nose.
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an electronic nose, is basically an electronic equivalent of a - if i remember this right - glass receptacle with chalk at the bottom, you use a little hand held pump to bring the "air" into the receptacle which gets trapped in to the chalk. you then analyse the chalk for the compounds!!!
damn, that is probably wrong but close - i hope
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found this
The University of Warwick has been actively involved in the research and development of electronic nose instrumentation since the early 1980s
here: http://www2.warwick.ac.uk/fac/sci/eng/eed/research/srl/contents/current_research/electronic_nose/
my memory being what it is, i may be wrong on the chalk thing. but im sure its pretty close.
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found this
The University of Warwick has been actively involved in the research and development of electronic nose instrumentation since the early 1980s
here: http://www2.warwick.ac.uk/fac/sci/eng/eed/research/srl/contents/current_research/electronic_nose/
my memory being what it is, i may be wrong on the chalk thing. but im sure its pretty close.
As you say, I don't think they use chalk (although it is plausible that it might once have been used).
The point is that there are many ways of creating electronic noses, although the use of coated semiconductor sensors is certainly a cheap and compact way of doing it, although mass spectrometry and light spectroscopy are other ways.
The point is still that all of these methods have their way of detecting chemicals in the environment.
http://science.nasa.gov/headlines/y2004/06oct_enose.htm
That's why NASA is developing the Electronic Nose, or ENose for short. It's a device that can learn to recognize almost any compound or combination of compounds. It can even be trained to distinguish between Pepsi and Coke. Like a human nose, the ENose is amazingly versatile, yet it's much more sensitive.
"ENose can detect an electronic change of 1 part per million," says Dr. Amy Ryan who heads the project at JPL. She and her colleagues are teaching the ENose to recognize those compounds -- like ammonia -- that cannot be allowed to accumulate in a space habitat.
Here's how it works: ENose uses a collection of 16 different polymer films. These films are specially designed to conduct electricity. When a substance -- such as the stray molecules from a glass of soda -- is absorbed into these films, the films expand slightly, and that changes how much electricity they conduct.
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fscience.nasa.gov%2Fheadlines%2Fy2004%2Fimages%2Fenose%2Fsensor_strip2.gif&hash=e303d01f554e409c1382625615965b39)
Because each film is made of a different polymer, each one reacts to each substance, or analyte, in a slightly different way. And, while the changes in conductivity in a single polymer film wouldn't be enough to identify an analyte, the varied changes in 16 films produce a distinctive, identifiable pattern.
Amongst other things, the above nose can sense 16 different chemical groups, whereas the human genome has about 347 different genes encoding for odours (I have not been able to determine how many different odour groups humans can detect, but it is likely that it is much greater than the 16 above).
Thus, while the machine sensor can be far more sensitive than the human nose, and can be fine tuned for specific environments, it probably is less selective than its human counterpart (which itself would be less selective or sensitive than a dogs nose).
There is no doubt that one can build electronic noses that can detect scents that the human nose could never detect; but it is still likely that it cannot detect with the same selectivity the whole variety that the human nose can detect at once.
Thus, one cannot say that because an electronic nose can detect something, that a human nose must be able to detect it, or visa versa (or even that every human nose can detect the same - and ofcourse, one can then speculate about what a dog might sense).