Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!att!cbnews!military
From: ssc-vax!wanttaja@beaver.cs.washington.edu (Ronald J Wanttaja)
Newsgroups: sci.military
Subject: Re: Infra-red detection
Message-ID: <12570@cbnews.ATT.COM>
Date: 23 Dec 89 06:05:20 GMT
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From: ssc-vax!wanttaja@beaver.cs.washington.edu (Ronald J Wanttaja)

> While not an expert, I believe the distance of the sensor from the
> source is also important, especially because the atmosphere absorbs
> radiation except at certain wavelengths.  Thus, viewed
> from space, an oil fire has the same infra-red radiation pattern
> as a missile exhaust plume.  Given this look-alike phenomenum,
> the term "signature" is very misleading.
> 
> Are satellite sensors sufficiently sensitive to detect residual
> differences in spectroscopic distributions as to reliably
> differentiate between various hot sources?  I don't believe so.
> Can anyone enlighten me?

Stationary sources don't cause much problem.  Oil well fires differ from
missile plumes in two important categories:  They don't move, and they
don't vary significantly within short periods of time.  Missiles don't just
turn on and off; there is a distinctive time-intensity history for each
than can be used to determine missile type.

Motion is also important, of course, since oil wells don't generally move.
Missiles accelerate.  

So, normally there's little problem telling an oil well fire from missile
launches.  However, in weird cases, the software can be fooled... that's
why there are men (and women) in the loop.

However, as for telling a stationary tank from a bakery, a satellite would
be in sad shape, for the reasons you mentioned.

					  Ron Wanttaja
					  (ssc-vax!wanttaja)