Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uwm.edu!ogicse!unicorn!n8035388
From: n8035388@unicorn.wwu.edu (Worth Henry A)
Newsgroups: sci.space.shuttle
Subject: Re: Shuttle Status for 09/19/90 (Forwarded)
Message-ID: <1990Sep21.224434.29513@unicorn.wwu.edu>
Date: 21 Sep 90 22:44:34 GMT
References: <1990Sep20.192923.5119@news.arc.nasa.gov> <3614@awdprime.UUCP>
Reply-To: n8035388@unicorn.WWU.EDU (Worth Henry A)
Organization: Western Washington Univ, Bellingham, WA
Lines: 27

In article <3614@awdprime.UUCP> tif@doorstop.austin.ibm.com 
   (Paul Chamberlain) writes:
>In article <1990Sep20.192923.5119@news.arc.nasa.gov> yee@trident.arc.nasa.gov 
    (Peter E. Yee) writes:
>>               Engineers are currently planning a helium signature test on
>>          the shuttle's liquid fuel feed lines on Saturday.
>I hope they intend to do lots of leak tests _before_ they get
>to the deadline.

    Unfortunately, the current leaks were detected after the systems had been
cold-soaked at cryogenic temps. If the helium is not cold enough, the 
physical size of the leaks not large enough, the humidity is not just right,
the lead engineer's biorythm not in sync, ... these and perhaps other leaks 
will not show up until they fill her up with H2 (and perhaps even O2 as 
well), and maybe not even then. And, as someone else has pointed out, if 
they have to go to that much trouble, it might as well be a launch attempt
(they might just get lucky). 

    Of course, a trial run might be worthwhile in the case of missions with 
tight launch windows. But then again, what new problems will be created by 
the thermal (and other) stresses of a trial run? This is hardly non-
destructive testing. 

    Additionally, the shuttles are not being stored in a stasis field
(the unused Saturns are not be the only spacecraft that birds and 
insects are building nests in ;-) ), the longer this goes on and the more 
NASA has to tinker, the worse it is going to get. :-(