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From: eder@ssc-vax.UUCP (Dani Eder)
Newsgroups: net.columbia
Subject: Re: Shuttle "self-destruct system?"
Message-ID: <3@ssc-vax.UUCP>
Date: Tue, 26-Jun-84 13:26:03 EDT
Article-I.D.: ssc-vax.3
Posted: Tue Jun 26 13:26:03 1984
Date-Received: Sat, 30-Jun-84 03:32:08 EDT
References: <261@ihu1h.UUCP>
Organization: Boeing Aerospace, Seattle
Lines: 47

[26 June 1984]

     It is officially called the 'range safety system'.  Following are
quotes from the "Space Shuttle News Reference".  That is what NASA gives
reporters to use in writing feature articles., and the Rockwell International
STS Press Information book, which is much more technical.

     "Each Solid Rocket Booster has a systems tunnel that provides protection
and mechanical support for the cables associated with the electrical and
instrumentation subsystem and the linear-shaped explosive charge of the
range safety system.  The tunnel extends along almost the entire length of
the booster." [page 2-25]

     "RANGE SAFETY SYSTEM

     The Shuttle vehicle has three range safety systems (RSS's).  One is
located in each SRB and one in the external tank.  Any one, or all three
is capable of receiving two command messages (arm and fire) transmitted
from the ground station.  The RSS is used only when the Shuttle vehicle
violates a launch trajectory red line [comment: that means it is heading
for Cocoa Beach or Disney World instead of where it should be going].

     An RSS consists of two antenna couplers, command receivers and command
decoders, a dual distributor, a safe and arm device with two NSI's [NSI=
NASA Standard Initiator=a standard electrically fired pyrotechnic charge
used for all kind of things on the Shuttle, like igniting motors and
cutting restraining bolts], two confined detonator fuse (CDF) manifolds,
and two linear shaped charges(LSC's).

     The antenna couplers provide the proper impedance for radio frequency
(RF) and ground support equipment commands.  The command decoders use a 
coded plug to prevent any RF signal other than the proper RF signal from
getting into the distributors.  The distributors contain the logic to
supply valid destruct commands to the RSS pyrotechnics.

     The NSI's provide the spark to ignite the CDF, which, in turn, ignites
the LSC for Shuttle vehicle destruction.  The safe and arm device provides
mechanical isolation between the NSI's and the CDF before launch and
during SRB separation.

     The first message, arm, allows the onboard logic to enable a destruct
an illuminates a light on the flight deck diplay and control panel
at the Commander and Pilot stations [astronauts proceed to wet pants].
The second message transmitted is the fire command."  [page 78]

Dani Eder /Boeing Aerospace Company /ssc-vax!eder /