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From: john@frog.UUCP (John Woods, Software)
Newsgroups: net.columbia
Subject: Re: Challenger SRBs
Message-ID: <344@frog.UUCP>
Date: Mon, 3-Feb-86 12:20:26 EST
Article-I.D.: frog.344
Posted: Mon Feb  3 12:20:26 1986
Date-Received: Fri, 7-Feb-86 09:44:18 EST
References: <4270@mhuxd.UUCP> <6339@utzoo.UUCP>
Organization: Charles River Data Systems, Framingham MA
Lines: 45

Henry (>) says to someone (>>) in 6339@utzoo.UUCP

> > ... Yet today, NASA said that
> > they were destroyed by the range safety officer because one of them
> > was headed toward a populated area...
> 
> What probably happened is that a fragment of one stayed attached to one
> of the chutes, which managed to open.  The destruct system doesn't reduce
> them to atoms.

In fact, according to the Monday Boston Globe, "James Mizell, a retired NASA
engineer working as a consultant to the space agency, said yesterday that in
a ''thrust termination'' procedure, explosive charges were used to ''cut the
top and bottom off, disableing the rockets.'' [PARAGRAPH] Under the procedure
burning fuel then fires from both ends, Mizell said, stopping the rocket's
forward motion."  And thus, they expect to recover fairly sizable pieces of
the SRBs (if they survived hitting the water faster than normal).

> > ...  Am I correct in my understanding that, under less catastrophic
> > conditions, the SRBs are capable of independent guidance, at least to keep
> > them clear of the orbiter after jettisoning following burnout or during
> > an abort?
> 
> 
> My recollection (which may be wrong) is that there basically is *no* abort
> available until SRB burnout, because there is no way to shut them down
> (short of destruction) and the jettison system can't safely cut them loose
> while the attachment points are carrying millions of pounds of thrust.

I would think to agree with this, but it was reported by NASA that because
the SRB nosecones (the second was just recovered Sunday, BTW) both had their
separation rockets intact and unfired, the pilot did not "hit the 'ditch
button'" to separate early.  Hence, I guess that it is considered possible
to separate from the SRBs even while they are burning (possibly because
safety is a relative thing...).

--
John Woods, Charles River Data Systems, Framingham MA, (617) 626-1101
...!decvax!frog!john, ...!mit-eddie!jfw, jfw%mit-ccc@MIT-XX.ARPA

This space dedicated to Challenger and her crew,
Francis R. Scobee, Michael J. Smith, Ellison S. Onizuka, Judith Resnik,
Ronald E. McNair, Gregory B. Jarvis, and Christa McAuliffe.

"...and slipped the surly bonds of Earth to touch the face of God."