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Date: Wed, 7 Jul 1999 16:33:10 -0400
To: mmachado@pop500.gsfc.nasa.gov, dmyers@pop500.gsfc.nasa.gov, ccazeau@pop500.gsfc.nasa.gov, jmaldona@pop500.gsfc.nasa.gov, bpickrel@pop500.gsfc.nasa.gov, dmalone@pop500.gsfc.nasa.gov, pdouglas@pop500.gsfc.nasa.gov, tafkhami@pop400.gsfc.nasa.gov, jameraul@pop400.gsfc.nasa.gov, gkinnama@pop500.gsfc.nasa.gov, tbevilacqua@hotmail.com, rsodano@pop500.gsfc.nasa.gov, whitec@thorin.atsc.allied.com, william.worrall@gsfc.nasa.gov, enace@pop500.gsfc.nasa.gov, ad@srl.caltech.edu, steves@srl.caltech.edu, msuarez@pop800.gsfc.nasa.gov, ngilotra@csc.com, btucker2@csc.com, cchang8@csc.com, csprouse@cscmail.csc.com, erc@cosmicra.gsfc.nasa.gov, carline.cazeau@alliedsignal.com
From: Mike Machado <mmachado@pop500.gsfc.nasa.gov>
Subject: ACE Weekly 7_7_99

Current spacecraft and ground system status is nominal.

Executed successful orbit and attitude maneuvers on Friday, July 2nd.
Orbit Maneuver Start Time=18:12:04     Orbit Maneuver End Time=18:13:33
Attitude Maneuver Start Time=19:08:18     Attitude Maneuver End Time=19:15:10
  Pre-Maneuver    HGA = 4.66 deg     Pre-Maneuver Sun Angle =  5.12 deg
  Post-Maneuver  HGA = 4.0 deg     Post-Maneuver Sun Angle =  13.1 deg
  Current S/C Range:  1529514.06   km

Anomalies: DSS-61 was unable to support pass due to an inoperative
transmitter. Failed over to DSS-27 for the entire support. See DR #L03423

The SWEPAM electron instrument lost at least 3 days of science over the
weekend due to a procedural error during calibration. The calibration
procedure should be run while in SCIENCE format. When the calibration
procedure is run (every Friday or Saturday depending on maneuvers), it
"remembers" the instrument initial state, performs the calibration, and
returns the instrument to that initial state. The calibration procedure was
run in ADC format, stopped and rerun after switching to SCIENCE format.
During the second execution, the initial state was incorrect as the
instrument was still in calibrate mode from the first execution of the
procedure. It remained in calibrate mode over the weekend until commanded
to the normal cycle on Tuesday.

The ACE FOT is planning to alter this procedure to prevent this from
happening again. Also, the constraint will be documented and training will
be conducted.

==========================================================================
Michael J. Machado
Realtime Operations Supervisor/ Technical Lead Engineer
Advanced Composition Explorer Flight Operations Team
http://acefot1.gsfc.nasa.gov/ACE_MOC_HOME.html
AlliedSignal Technical Services Corporation
corp. email: machadm@thorin.atsc.allied.com
phone: (301)286-7071  pager: (301)708-8272   fax: (301)286-0218
email: mmachado@pop500.gsfc.nasa.gov
==========================================================================