ACE Weekly 09/10/04 - 09/16/04 All ACE spacecraft subsystems are performing nominally. A "Dog-Leg"=20 attitude maneuver was successfully executed on 09/10/04 but not without=20 problems (see Anomalies section). The next attitude maneuver is scheduled= =20 for 09/17/04. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D Orbit Events: The ACE transit of the Solar Exclusion Zone (SEZ) concluded on=20 09/11/04. The minimum Sun angular radius was 0.32 degrees (as seen from=20 Earth's center) on 08/30/04. The next SEZ crossing will occur in the=20 Nov-Dec time frame. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D OCRs Executed: None =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Ongoing Activities: TAPS: - Installation of TAPS release 4.3 occurred on 07/20/04. FOT testing of=20 this release is ongoing. -- Of the 6 DRs fixed in release 4.3, all have been verified. -- Two (2) new DRs have been opened to date and additional DRs may=20 follow based on recent findings. ---------------------------------------------------------------------------- Automation (ROBOTT): - On 08/25/04, ROBOTT v0.8.1 was installed on String 1 (OCR GND-143). -- Operations is being conducted in the "auto" mode with the FOT closely= =20 monitoring and noting any discrepancies. -- ROBOTT is NOT being used for maneuvers. - ROBOTT v0.9 is scheduled for delivery to Strings 2 & 3 on 09/21/04. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D Extra Spacecraft Activities: None =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Anomalies: DOY 04254 (09/10/04) ACE Anomaly S04-0008 - Ordinance Fire Component Red=20 High Limit Violation At 16:34:42 Mnemonics ORD_AB_P1 and ORD_AB_P2 violated their Red High=20 limits. At 16:34:44 both mnemonics came back within their high/low=20 limits. During the time of 16:34:42 - 16:34:44 the FOT was conducting an=20 Attitude Maneuver. This violation also occurred on DOY 03157 (S03-0011)=20 and DOY 03267 (S03-0020). IMPACT: None DOY 04254 (09/10/04) ACE Anomaly S04-0009 - Thruster Firings Every Other=20 Rotation During the 2nd attitude maneuver on DOY 254 2004, thruster firings occurred= =20 at every other rotation. When this occurs the nutation of the spacecraft=20 increases significantly. The nutation after the maneuver was approximately= =20 7=B0 and dropped to 1=B0 within 4 hours. Nutation after a nominal maneuver= is=20 typically 0.5=B0. The reasons for the thrusters firing every other rotation= =20 is being investigated. The same maneuver conditions have been used=20 successfully in the past. Possible reasons include a longer time for=20 spacecraft relay switching or a spin rate different than that reported by=20 the star scanner. IMPACT: All thruster firings were completed and the=20 spacecraft is at the correct attitude. No data loss occurred. The science= =20 center has been notified so that they can assess the impact to data quality. DOY 04256 (09/12/04) ACE Anomaly G04-0104 - GDS 26m (DSS-16) Command Mod=20 Index Reset Commands were not getting into the S/C and FOT requested DSS-16 to reset=20 the command mod index. Once reset, commands were received and processed by= =20 the S/C. IMPACT: Delayed pass activities. Had the FOT not been=20 monitoring, ROBOTT would have paused C&C and no other pass=20 activities/commands would have been executed. DR# G104798 DOY 04257 (09/13/04) ACE Anomaly G04-0105 - MAD 26m (DSS-66) Wrong Command= =20 Mod Index FOT noticed extremely low AGC levels during commanding (-130db) and=20 requested DSS-66 manually enter the correct Command Mod Index. Nominal AGC= =20 levels were reported after change made. IMPACT: Delayed pass=20 activities. Had the FOT not been monitoring, ROBOTT would have paused C&C= =20 and no other pass activities/commands would have been executed. DR# = M102735 DOY 04258 (09/14/04) ACE Anomaly G04-0106 - GDS 26m (DSS-16) Command Mod=20 Index Reset Commands were not getting into the S/C and FOT requested DSS-16 to reset=20 the command mod index. Once reset, commands were received and processed by= =20 the S/C except the C&DH B Poke which was never verified. That problem is=20 under-investigation. IMPACT: Delayed pass activities. Had the FOT not=20 been monitoring, ROBOTT would have paused C&C and no other pass=20 activities/commands would have been executed. DR# G104806 DOY 04259 (09/15/04) ACE Anomaly G04-0107 - ROBOTT C&C Failure During= G_ACEUP C&C never acquired CC privilege and paused during the execution of=20 procedure G_ACEUP. IMPACT: By the time the problem was fixed by the FOT=20 data was online so the procedure G_PRECAL was not able to be executed. Had= =20 the FOT not been monitoring, ROBOTT would have paused C&C and no other pass= =20 activities/commands would have been executed. DR CDSID 21015 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Glen A. Miller ACE Flight Operations Observatory Engineer Honeywell Technology Solutions Inc. Goddard Space Flight Center Building 14, Room W10A Mail Stop 428.2 Greenbelt, MD 20771 Office: 301-286-7071 Pager: 800-425-3174 Fax: 301-286-1729 gamiller@pop500.gsfc.nasa.gov ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~