Can we 'sniff out' explosives at a distance?

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Paul Anderson

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Can we 'sniff out' explosives at a distance?
« on: 06/01/2010 12:30:02 »
Paul Anderson  asked the Naked Scientists:
Hi Chris and team,

Drug dogs sniff out drugs.  Is there any way that what they sniff can be made visible on some sort of distant electronic instrument?

Astronomers look at distant objects and say that there is presence of this or that chemical.

I have just heard on the BBC about the lives lost in the most recent bombings in Baghdad.

If folk at check points had a gadget which could detect bomb material from a distance, they might be able to stop these bombers getting close to the check points. I admit that this would only be applicable to a situation out in the open desert, on the approaches to country or city boundaries, and not where there are check points in the hearts of cities.

What do you think?
« Last Edit: 06/01/2010 12:30:02 by _system »


Offline LeeE

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Can we 'sniff out' explosives at a distance?
« Reply #1 on: 06/01/2010 15:26:17 »
Olfactory sensors need a molecule to travel from its source to the sensor, so while dogs may be able to smell explosives etc. they can only identify their location by intensity.  If you're outdoors then you can assume that the source is upwind of you, but that's about all.

This is the main difference between olfactory sensors and light/radio telescopes; light/radio waves follow a 'straight' line through space, so you know that if you see something when you point your telescope towards it, it's where you're pointing towards.  If the source of aromatic molecules is downwind of you though, you'll detect nothing as everything is being blown away from you.  Aromatic molecules also move much more slowly through the air too, and are subject to the air turbulence caused by anything moving through the air, so it's possible for someone who's walking quickly to leave much of the 'smell' behind them.
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