Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!ucsd!ucbvax!hplabs!hpfcso!hpfinote!ddj
From: ddj@hpfinote.HP.COM (Doug Josephson)
Newsgroups: sci.space.shuttle
Subject: Re: RSO (was: Re: Blowing up the Shuttle)
Message-ID: <19500004@hpfinote.HP.COM>
Date: 9 Apr 90 03:54:03 GMT
References: <1990Apr5.163338.3198@uokmax.uucp>
Organization: Hewlett Packard CICD
Lines: 31

In article <1990Apr6.024706.15843@utzoo.uucp> henry@zoo.toronto.edu
(Henry Spencer) writes:

>I don't recall hearing of this, and several of the usual references don't
>mention it.  The Apollo spacecraft's electrical systems were really knocked
>for a loop, but the (completely separate) computers of the Saturn V were
>better protected and were not bothered by the lightning hit.

From "Apollo:  The Race to the Moon" by Murray & Cox, pg. 379:
(quoted without permission)

"In the case of the IU (Instrument Unit), induced currents reached the
guidance system's circuits but the computer software kept the platform from
tumbling.  In addition, the incident on Apollo 12 dramatically vindicated
the decision early in the 1960s to have separate guidance systems for the
spacecraft and the launch vehicle."

However, the CM did lose its guidance platform, since the fuel cells were
disconnected from the power distribution buses.  The fuel cells were
reconnected when telemetry established they had been disconnected, and
the CM platform was re-aligned using star sightings in Earth orbit.

Now, IMHO, if the IU platform was not affected, the launch vehicle should
not have been rolling excessively.  I think the major concern was whether
or not to abort the ascent - if they had, then the RSO might have come
into play.

BTW, the above book has great technical details about the various Apollo
flights - I recommend it highly!

Doug Josephson  ddj@hpfinote.HP.COM  Fort Collins, CO