Forum on Risks to the Public in Computers and Related Systems

ACM Committee on Computers and Public Policy, Peter G. Neumann, moderator

Volume 1: Issue 44

Wednesday, 29 Jan 1986

Contents

Shuttle SRB/MFT self-destruct mechanisms

Dusty Bleher

Herb Lin

Martin Moore

Challenger speculation

Herb Lin

Shuttle SRB/MFT Self-destruct mechanisms

Organization: Commodore-Amiga Inc., 983 University Ave #D, Los Gatos CA 95030

[PGN wrote

  >One unvoiced concern from the RISKS point of view is the presence on each
  >shuttle of a semi-automatic self-destruct mechanism.  Hopefully that
  >mechanism cannot be accidentally triggered.   ]

Please Note, and cease to spread your unfounded rumor!
  ONLY the SRBs and the MFT/mate assy have a destruct mechanism.  The shuttle
  is NOT provided with such a mechanism, any more then an L-1011 is!

Dusty Bleher  (@@) (408) 395-6616 x265 (wkdays PST)

                [Yes, Martin Moore noted that in RISKS-1.43.  Fortunately
                 L-1011's do not have to take off amidst Solid Rocket
                 Boosters and External Fuel Tanks!  Thanks.  PGN]

Reliability of Shuttle SRB/MFT self-destruct mechanisms

To: mooremj@EGLIN-VAX.ARPA
cc: "RISKS-LIST:"@MC.LCS.MIT.EDU, risks@SRI-CSL.ARPA

Thanks for your piece.  Can you discuss at all the actual devices used on
the SRBs and the External Tank to set off explosions?  What ensures that
they work as expected?

Reliability of Shuttle SRB/MFT self-destruct mechanisms

To: "lin" 

 Challenger speculation
Herb Lin <LIN@MC.LCS.MIT.EDU>
Wed, 29 Jan 86 18:18:19 EST
To: kyle.wbst@XEROX.COM
cc: LIN@MC.LCS.MIT.EDU, "RISKS-LIST:"@MC.LCS.MIT.EDU,
    aviation@R20.UTEXAS.EDU, CMP.WERNER@R20.UTEXAS.EDU,
    neumann@SRI-CSL.ARPA

    From: kyle.wbst at Xerox.COM

    Does anyone know if a rifle shot on the big tank would be enough to
    structurally weaken it such that during that portion of the launch with
    maximum stress the thing might rupture?

It is obvious that at the time of the explosion, no rifle bullet hit
it.  Thus, any shot must have been fired much sooner.  The rifle shot
must then be timed in such a way that it is fast enough to weaken the
casing, but not strong enough to penetrate it.  It seems that that
window is pretty small.

If you are into pure, unadulterated speculation, another possibility
is that a bullet was fired into an SRB while it was on the ground, and
lodged there.  When the fuel burned to that point, a jet leaked out,
and triggered an explosion.




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