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From: karn@epic.bellcore.com (Phil R. Karn)
Newsgroups: sci.space.shuttle
Subject: Re: Fire near tail of shuttle after landings.
Message-ID: <1991Apr12.222921.6034@bellcore.bellcore.com>
Date: 12 Apr 91 22:29:21 GMT
References: <1991Apr11.223534.12896@pandora.matrox.com> <1076@hrshcx.csd.harris.com> <1991Apr12.034927.25257@gn.ecn.purdue.edu>
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In article <1991Apr12.034927.25257@gn.ecn.purdue.edu>, jonkatz@gn.ecn.purdue.edu (Jonathan W. Katz) writes:
|> >.     Sometime in 1985 I remember seeing a shuttle landing on TV where
|> >. there was a clean flame emanating from near the base of the tail 
|> >. after the orbiter had come to a stop.

|> Actually, what he saw back in '85 (?) was an actual fire in the Columbia
|> engine room that did a lot of damage.

You're referring to STS-9 (late 1983), and although there was indeed a
fire inside an engine bay AND an externally visible plume, these were
completely independent phenomena. The (accidental) fire was NOT
visible - the external plume was just the APU exhaust, as mentioned by
others here.

The APUs run on catalytically decomposed hydrazine (N2H4). When you
decompose hydrazine, you get hot nitrogen and hydrogen. Hydrogen is
flammable, so it can burn if oxygen is present. This is normal, expected
and safe.

Phil