Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!cs.dal.ca!iisat!roberts
From: roberts@iisat.uucp (Greg Roberts)
Newsgroups: sci.space.shuttle
Subject: Shuttle Range Safety System
Keywords: SRB
Message-ID: <1989Oct27.025748.28234@iisat.uucp>
Date: 27 Oct 89 02:57:48 GMT
Organization: International Information Service, Dart., NS.
Lines: 65

This is extracted from "National Space Transportation System Reference"
                        Volume 1
                        Systems and Facilities
                        June 1988

It is reproduced without permission from NASA

Range Safety System

The shuttle vehicle has three RSSs. One is located in each SRB and one in
the external tank. Any one or all three are capable of receiving two command
messages (arm and fire) transmitted from the ground station. The RSS is used
only when the vehicle violates a launch trajectory red line.

An RSS consists of two antenna couplers, command receivers/decoders, a dual
distributor, a safe and arm device with two NSDs, two confined detonating
fuse manifolds, seven CDF assemblies and one linear-shaped charge.

The antenna couplers provide the proper impedence for radio frequency and
ground support equipment. The command receivers are tuned to RSS command
frequencies and provide the input signal to the distributors when an RSS
command is sent. The command decoders use a code plug to prevent any command
signal other than the proper command signal from getting into the distributors.
The distributors contain the logic to supply valid destruct commands to the
pyrotechnics.

The NSDs 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 NSDs and the CDF before launch and during the SRB
separation sequence.

The first message, called arm, allows the onboard logic to enable a destruct
The first message, called arm, allows the onboard logic to enable a destruct
and illuminates a light on the flight deck display and control panel at the
commander and pilot station. The second message transmitted is the fire
command.

The SRB distributors in the SRBs and the ET are cross-strapped together.Thus
if one SRB received an arm or destruct signal, the signal would also be sent
to the other SRB and ET.

CDF = confined detonating fuse
NSD = NASA standard detonator
LSC = linear shaped charge

my text from here..


From the figure on page 52, the antennas are located located on the nose of
each SRB, two located opposite eachother along the Z axis of the vehicle.

Now...here is the million dollar question. Once the light comes on in the
flight deck area, and everyone quits playing cards, what does the crew do
next?






 
-- 
Greg Roberts	              International Information Service (IIS)
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