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From: crad@polari.UUCP (Charles Radley)
Newsgroups: sci.space,sci.space.shuttle
Subject: Re: space news from Nov 5 AW&ST
Summary: the effects of deleting the truss are misrepresented
Message-ID: <2897@polari.UUCP>
Date: 16 Dec 90 04:10:42 GMT
References: <1990Dec11.055832.24321@zoo.toronto.edu>
Organization: Seattle Online Public Unix (206) 328-4944
Lines: 27



+but now it is out in the open.  The long truss is probably not long
+for this world, in particular:  a Goddard project to attach science
+payloads to it has been cancelled, and the request for bids for the
+assembly training facility in Houston has been withdrawn.  The
+leading idea right now is simply to retain the central cluster of
+modules, but kill the truss.  Among other advantages, the resulting
+station should have gravity-gradient stability, eliminating
+attitude-control thruster firings that eat fuel and bother the
+microgravity people.
-
This is nonsense. The current Freedom is already gravity gradient
stabilized, and The Truss is the very feature which makes gravity
gradient stabilization possible, since it gives the solar arrays
sufficient degrees of freedom to continuously track the Sun
independent of the attitude of the main part of the station, which is
pointing at the earth.   
  Deleting the truss means the station will no longer be gravity
gradient stabilized because the solar arrays will have only one
degree of freedom.   This means that the entire station will have to
be kept more or less sun pointing, and gravity gradient pointing will
no longer be possible.
  Instead of reducing thruster firings and fuel consumption, deleting
the truss will substantially increase both.
 
:wq