From: Jim Ray (USNO 202-762-1444) <jimr@maia.usno.navy.mil>
Message-Id: <200003031520.KAA28030@maia.usno.navy.mil>
Subject: [IGSMAIL-2731]: ION paper on controlling momentum
To: igsmail@igscb.jpl.nasa.gov
Date: Fri, 03 Mar 2000 10:20:06 EST
Sender: owner-igsmail
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IGS Electronic Mail      03 Mar 07:19:51 PST 2000      Message Number 2731
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Author: Jim Ray

In reference to IGS Mail #2642 (22 Dec. 1999), an electronic preprint of
the paper by Violet et al. on "Navigation accuracy or satellite health?
Controlling momentum on aging GPS satellites" is now available at
http://maia.usno.navy.mil/gpst/refs/violet-ion.doc.Z .  The format of
the paper is MS/Word; it is unix compressed (210.6 kB).  It will be
published in the Proceedings of the ION GPS'99 meeting (Nashville, TN,
14-17 September 1999).

From IGS Mail #2642:

> The authors describe the evolution of the constellation management by
> the 2nd Space Operations Squadron at Schriever AFB (Colorado Springs, CO)
> in view of the degrading attitude control systems on some of the older
> spacecraft.  Currently seven satellites are affected (SVN 14, 15, 16, 18,
> 19, 24, and 29), requiring periodic thruster-controlled momentum dumps.
> Partly to relieve the workload on the operations staff, the thruster-
> controlled system has transitioned over the past two years to an
> automonous mode consisting of more frequent, but smaller momentum dumps.
> The effect of these thrustings on the GPS orbits is evident in the IGS
> results.

For further information, please consult the authors.