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From: karn@mouton.UUCP
Newsgroups: net.columbia
Subject: Re: Shuttle "self-destruct system?"
Message-ID: <91@mouton.UUCP>
Date: Tue, 26-Jun-84 18:10:41 EDT
Article-I.D.: mouton.91
Posted: Tue Jun 26 18:10:41 1984
Date-Received: Thu, 28-Jun-84 03:52:05 EDT
References: <940@ihuxi.UUCP> <2875@alice.UUCP>
Organization: Bell Communications Research, Inc
Lines: 21

A minor correction to Adam's comments about the range safety destruct
system.  The explosive charges are only on the external tank and on
the solid rocket boosters; none are on the orbiter itself. They
are actually long linear shaped charges which are designed to split the casing
of the booster or tank lengthwise, dumping the propellants and disintegrating
the casing. You can see these on the SRBs and ET as longitudinal 'ribs' running
for most of their length. (There are other ribs as well which contain
more mundane things like electrical cables and fuel lines, so not all
of them contain destruct explosives.)

The range safety system works by external radio command. I certainly
hope that the coding is reasonably secure, but I do remember when
I was on hand for the STS-9 launch that during the terminal stages
of the countdown (perhaps 10-15 minutes before launch) there was
an announcement that a "Range safety system test, using the actual
flight codes, had been successfully conducted". This could in theory
allow a terrorist to monitor the codes and retransmit them during flight.
Considering all the other precautions taken, I hope that it wouldn't
be quite this easy.

Phil