ACE Weekly 08/30/2011 - 09/05/2011 The SWICS instrument has not been generating science data since high voltages were disabled on 8/26/2011 (DOY 238). SWICS was powered off on 9/2/2011 (DOY 245) and will be powered on in the upcoming week. All other ACE spacecraft subsystems are performing as expected. ======================================================================== Orbit/Attitude: Type Attitude Date 08/30/2011 DOY 242 2011 Thrusters 2R 4R+ 4R- Duration 15:52 min Start 14:04:44z Stop 14:20:36z HGAStart -7.12deg HGAStop +8.12deg SunStart 11.60deg SunStop 6.26deg SpinStart 5.0110rpm SpinStop 5.0142rpm Nutation 0.05deg Firing 80 pulses FuelUsed 0.2523lbs FuelRemain 127.0312lbs FinalSCMass 1361.291lbs The next attitude maneuver is scheduled for Wednesday 09/21/2011. ======================================================================= OCRs: DOY 245 (09/02/2011) 1556-1604z SWICS MOCR 338 SWICS was powered down on 09/02/2011 as part of the investigation into the increased trigger rates anomaly (AR#S11-0002). The instrument team's analysis shows that the most likely cause is a malfunction with the hybrid timing discriminator in the time-of-flight (TOF) electronics. The powering off should reduce the temperature of the TOF electronics. The instrument will be powered back in the upcoming week. The high voltages will be raised if the instrument returns to its normal operating state. The SWICS internal temperature dropped 1C (1.5 to 0.5C) when the voltages were disabled on DOY 238. The internal temperature dropped another 0.5C (0.5 to 0C) after the attitude maneuver on DOY 242. And the temperature dropped 5C (0 to -5C) after SWICS was powered off on DOY 245. ======================================================================== Activities: Data Capture: 100% DOY 240-247 2011 The GRAIL mission is expected to launch 09/08/2011. ACE has reduced DSN antenna time during September. The current schedule has ACE losing ~15% data over 3 weeks in September. The data loss will be greater if there are problems with any of the passes. ======================================================================== Anomalies: None