ACE Weekly 11/13/2014 - 11/18/2014 Refer to the anomaly section for updates to the fuel system temperatures. All other ACE spacecraft subsystems are performing as expected. ======================================================================== Orbit/Attitude: Type Attitude Date 11/18/2014 DOY 322 2014 Thrusters 2R 4R+ 4R- Duration 8:45 min Start 16:36:54z Stop 16:45:39z ra,decStart 239.79,-9.97 ra,decStop 247.38,-9.82 ra,decExpect 248.34,-10.07 Deviation 0.98 deg (-11% short) HGAStart -9.16 deg HGAStop +8.87 deg SunStart 11.05 deg SunStop 16.31 deg SpinStart 5.0023 rpm SpinStop 5.0040 rpm Nutation 0.08 deg Firing 44 pulses FuelUsed 0.1399 lbm FuelRemain 102.6120 lbm FinalSCMass 1337.872 lbm The next attitude maneuver is scheduled for Tuesday 11/25/2014. ======================================================================== OCRs: None ======================================================================== Activities: Data Capture: 100% DOY 313-320 2014 ======================================================================== Anomalies: DOY 318 11/14/2014 S-ACE-0689 ITOS Command Graph Error The ITOS ground system generated an error early in the pass. (Command transmission has failed: dbus synchronous send/await: Message did not receive a reply) No further commanding (including playback of recorded data) was performed during the pass. ITOS was manually restarted after the pass. This is an occasionally recurring problem that last occurred 09/26/2014. IMPACT: Playback of recorded data slowly caught up over the next 4 passes. Update for S13-0001 - B1/B2 Fuel Tank Temperature Anomaly As reported last week (11/12/2014) and in previous reports: * Starting 10/14/2014, the tank heaters started cycling off. The Tank B1 temperature fluctuates ~4C as the tank heaters turn on and off. The other tank temperatures remain within 1C. * During the 11/5/2014 and 11/12/2014 maneuvers, the Tank B2 temperature increased and the -X External Fuel Line temperature decreased. The timing corresponded to the start of the maneuver and no heaters turned on/off at that time. When the maneuver had stopped, the temperatures returned to their normal temperatures over ~10 minutes. Updates for this week (11/18/2014): * Starting after the 11/12/2014 maneuver, the Tank B2 temperature has been fluctuating ~2C as the tank heaters turn on and off. * During the 11/18/2014 maneuver, the Tank B2 temperature did not increase as had happened on 11/5 and 11/2. But the -X External Fuel Line did decrease. Again, the timing corresponded to the start of the maneuver and no heaters turned on/off at that time. When the maneuver had stopped, the -X External Fuel Line returned to its normal temperature. The fuel system temperatures continue to be monitored. There is not yet a theory to explain the temperature changes in the Tank B2 temperature or the -X External Fuel Line temperature.