From: Cohen@.mdc.com (Andy Cohen)
Subject: Re: SSF Progress
Date: Fri, 18 Dec 92 23:44:47 GMT
Organization: MDA-W
Followup-To: sci.space
Distribution: sci

I'm very impressed that a Design Project leader would take the time to post
in such detail!

Many of what has gone between postings in this thread are interesting and
some are questionable.....Note that we on WP-02 (both MDA and NASA) are
currently looking at well over 200 contract changes.

Two changes of interest: 1. Change from crew-built-in-EVA approach to a
PreIntegrated Truss (PIT)i.e., prebuilt on the ground then shipped up to
orbit and attached to previous peices.... This was the biggy a couple of
years ago and was driven by the Fischer-Price (not the toymaker!) study on
EVA maintainance time...I personally believe that this was not the true
reason....I think it was because the truss elements (sticks) would not be
strong enough.....not to mention that the crew could never had built it all
by hand before using up all their air....The PIT was what MDA originally
wanted to do back in phase B, but I've heard they (NASA) wanted it built by
Astronauts....This was the biggest one and if we had started with this
approach in '88 a good amount of $ would have been saved.  True...due to
the shuttle's limitations and weight there is less power and a smaller
size.....  part of this change included halving the modules which saved
tons as well as eliminating two of the resource nodes.
2.  Another big change which is going through these days allows the
electronic devices to switch to backup components at failures....known as a
logical "string" as opposed to a physical...In the old way a physical
string is made up of a set of devices...multiple strings provided
reliability during failure...the system would switch to the other
string...However the additional backup devices were scrubbed out of the
program.... the strings were incomplete.....  The newer design allows the
systems to continue to operate after 2 failures have occured.  Devices
within the logical string switch rather than the whole string..in the old
way if a device failed, so would SSF.....This change is a direct result of
#1 above  as well as other scrubs....

These two big changes have had the most impact and get the most press.....
neither are due to ANY technical stupidity on the part of MDA....nor poor
mgmt practices.....

The fact is...SSF is a hard thing to do and we are ALL learning how to do
it as we go along.  True there were probably cheaper ways to go, but these
cheaper ways depend on hindsight.  This is a development program which in
unofficially fixed price...even though it's officially cost plus and
managed as such...

I repeat what I posted here months ago....SSF will teach us how to build
big massive structures in orbit.....you can't do much in space until you
know how to do that...... Killing SSF now would be almost as bad as
allowing Skylab to fall out of orbit (OK, maybe not that bad...).....In my
opinion what the program needs is extreme stability and enforced
accountability...  NASA mgmt must not be allowed to change and move on to
other jobs.....Too many NASA bigshots have stomped their way through the
program thinking they can wrestle it under control by banging their fist on
the table during big meetings then bullying everybody.....Then moving
on....  The upper mgrs should be forced to be accountable for stupid
expensive wastes....
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