ACE Weekly 12/26/2007 - 01/01/2008 All ACE spacecraft subsystems are performing nominally. ============================================================================ Orbit/Attitude: Type Attitude Date 12/28/2007 DOY 362 2007 Thrusters 2R 4R+ 4R- Duration 13:06 min Start 16:22:55z Stop 16:36:01z HGAStart -4.98deg HGAStop +7.45deg SunStart 10.85deg SunStop 6.77deg Nutation 0.44deg Firing 67 pulses FuelUsed 0.2196lbs FuelRemain 152.6968lbs FinalSCMass 1386.957lbs The next attitude maneuver is scheduled for Monday, 01/07/2008. Station-Keeping #46 has been tentatively scheduled for Thursday 01/17/2008. ============================================================================ OCRs: None ============================================================================ Activities: 34m HEF S-Band Transmitter DSS-45 was tested Monday 12/28/2007. The ACE MOC successfully binded at 19:41:00 (BOT-19min) but the bind was lost at 19:43:11. The ACE MOC software attempted a bind once a minute and was finally successful at 20:01:41. The reasons remain unknown (DR#C106089). The GSFC Metric Tracking Data Evaluation (MTDE) group received good Range and Doppler data. The uplink signal strength measured by the spacecraft was Hi-Gain Antenna = -98 dBm BroadBeam Antenna = -112 dBm This signal strength is more than adequate and is comparable to DSS-27 (another 34m antenna with 200W transmitter). The risk of data loss has increased for the December-January time frame. If there are problems with the passes, it may not be possible to acquire additional DSN time. Refer to 12/25/2007 weekly for further explanation. For 3 supports (Friday 12/14, Friday 12/21 and Wednesday 12/26), DSS-46 has had significant problems with transmitting commands received via SLE. DSN is aware of the problem and provided additional engineers to monitor the DSS-46 pass on Monday 12/31. During the Monday 12/31 pass, there were no problems observed. DSN is reviewing their log files for any differences in the configuration for these successful and unsuccessful passes. ============================================================================ Anomalies: DOY 360 12/26/2007 S-ACE-0259 G07-0111 DSS-46 SLE - CMDs Not Transmitted ACE MOC had a successful bind with the station. However, the station's SLE indicated commands received but not processed. Station rebooted the TCP but only one command would be successful and the bind would be lost. The station rebooted the TCP for each command sent until the playback had started. DR#C106073 IMPACT: SSR Playback delayed 2 hours. DOY 361 12/27/2007 S-ACE-0260 G07-0106 DSS-46 Red Due to Lightening The station's Antenna Interface Unit (AIU) appeared to have taken a direct lightning strike and could not be reset prior to the scheduled ACE track. IMPACT: Fortunately, additional DSN time was available and the SSR Playback was completed on DOY 362.