Mime-Version: 1.0 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 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 ==========================================================================