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From: dietz@SLB-DOLL.CSNET (Paul Dietz)
Newsgroups: net.space
Subject: Speculations on Shuttle Disaster
Message-ID: <8601291923.AA01088@s1-b.arpa>
Date: Wed, 29-Jan-86 12:53:08 EST
Article-I.D.: s1-b.8601291923.AA01088
Posted: Wed Jan 29 12:53:08 1986
Date-Received: Sat, 1-Feb-86 02:38:38 EST
Sender: usenet@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
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Some speculations on the cause of the accident:

(1) It's clear from the tapes that the biggest explosion occured right
    at the point in the ET where the oxygen and hydrogen tanks abut.  This
    explosion was almost certainly the result of mixing of the fuels and
    reduced the shuttle to fragments.  Most of the liquid fuel was still
    in the tanks at that time and would burn with the force of a small
    atomic bomb.  The "intertank" area is near the top of the ET, since
    the oxygen tank is smaller than the LH2 tank.

(2) The flame earlier on around the ET could have any of several
    explanations:

   (a) Hydrogen leaked from the ET and burned in air.  However, the
       flame was orange/yellow; I thought hydrogen flame was
       blue/white.  Perhaps some insulation was burned also.

   (b) Oxygen leaked from the ET and caused insulation or the aluminum
       tank structure to burn.  Does anyone know what the tanks are
       made of, and can it sustain a reaction with LOX?

   (c) A third possibility is that the TDRS satellite sprung a leak.
       It contains hydrazine, I believe; also, its booster contains some
       kind of propellant (liquid, I think).  If fuel leaked out some
       could have leaked out of the payload bay and burned behind the
       main tank.  When the flame propagated back to the cargo bay
       the shuttle could have been blown apart, puncturing the ET.
       The tape seems to show the first explosion occuring between
       the orbiter and the ET, and significant flame occured on the
       outer side of the orbiter just before the big explosion.  I
       don't know if the shuttle computers can monitor the TDRS, so
       this is a real possibility.

   (d) The flame was SRB exhaust from a SRB defect (see below).

(3) If the ET was the source of gas a possible damage mechanism would be
    defects in the SRB's.  If a gas jet escaped from the side of the
    booster it could slice right into the ET.  The SRB's being used were
    the fairly new ones with filament wound casings.  Recovery of these
    should be possible and should confirm/deny this theory.

(4) Damage could have occured to the ET, which could have failed
    catastrophically when (a) less fuel was present to brace it, and (b)
    the throttle was pushed back up after max Q.  If the tank ripped
    this could explain what looks like the progressively larger amount
    of flame around the ET and the sudden failure of the intertank
    bulkhead.  It would have to sudden, though, otherwise the shuttle
    computers would jettison the tank when the pressure dropped.
    It has been suggested that they did just that, and that flash
    between the shuttle and the tank just before the big explosion
    was the explosive bolts going off.  This might have suddenly
    stressed the tank, causing catastrophic failure.  Telemetry should
    reveal if this in fact occured.