ACE Weekly 01/24/2012 - 01/30/2012 All ACE spacecraft subsystems are performing as expected. ======================================================================== Orbit/Attitude: Type Attitude Date 01/30/2012 DOY 030 2012 Thrusters 2R 4R+ 4R- Duration 17:31 min Start 19:52:38z Stop 20:10:09z HGAStart -7.21deg HGAStop +7.26deg SunStart 6.47deg SunStop 9.63deg SpinStart 5.0441rpm SpinStop 5.0492rpm Nutation 0.04deg Firing 89 pulses FuelUsed 0.2765lbs FuelRemain 123.9884lbs FinalSCMass 1358.248lbs The spacecraft will drift to a sun angle of 1.6 degrees on Wednesday 02/08/2012. This is below the originally proposed 2 degree sun angle. The FOT recommends keeping the current attitude and not performing another maneuver. The sun sensor can read sun angles down to +/- 0.25 degrees and 1.6 degrees is expected to be more than enough to create a sun pulse. If the sun pulse does stop occurring, the ACE Science Center can generate a pseudo sun pulse when processing the science data. There will be no nutation as the spacecraft drifts to 1.6 degrees. The current attitude will give a slightly better (0.5dB) RF signal during the Solar Exclusion Zone transit (SEV<1.0degrees). MOCR 387 has been resubmitted for Mission Director approval. The next attitude maneuver is scheduled for Tuesday 02/21/2012. ======================================================================= OCRs: DOY 026 (01/26/2012) 1909-1911z CRIS-011 The Image Intensifier was powered on after being automatically safeguarded during the previous week's solar activity (DOY 023-07:46:38z). This OCR was last executed on 12/15/2006. DOY 027 (01/27/2012) 2112-2119z SIS-044 During the most recent large SEP event (January 24, 2012), the Matrix detector strips # 38 and 47 on M1B HV side became noisy. Strip # 47 had its threshold already raised, but now the noise level is beyond the threshold control. Strip # 38 did not have its threshold raised, so it will be raised now at the expense of strip # 61 as there is a limit of 20 strips. ======================================================================== Activities: Data Capture: 100% DOY 022-029 2012 During last week's solar activity, the ULEIS shutter autonomously closed and reopened Sun Jan 22 2012, DOY 022 07:21:39z closed to 25% Tue Jan 24 2012, DOY 024 14:19:47z closed to 6% Tue Jan 24 2012, DOY 024 15:08:51z closed to 1% Wed Jan 25 2012, DOY 025 04:20:19z open to 6% Thu Jan 26 2012, DOY 026 07:02:27z open to 25% Thu Jan 26 2012, DOY 026 20:16:03z open to 100% There was no noticeable degradation (<0.2%) in the solar arrays from last week's solar storm. There have only been 4 days where the solar arrays have noticeably degraded ~1% due to solar activity (07/15/2000, 11/09/2000, 11/06/2001 & 10/29/2003) WS1 (18-meter antenna at White Sands) tracked ACE and forwarded data to the MMOC on Friday 01/27/2012. Unfortunately, the server at the MMOC crashed. The MMOC server has been improved and is now ready anytime WS1 is ready to test their equipment. ======================================================================== Anomalies: DOY 024 01/24/2012 S-ACE-0639 S12-0001 SWEPAM-E Overcount Alarm The SWEPAM-Electron Overcount Alarm occasionally flags during solar events. When it flags continuously (2 or more times in a row), we note it with an anomaly report and notify the instrument team. This is only the 4th solar storm when a continuous overcount alarm has occurred. The SWEPAM-Ion Overcount Alarm has never flagged throughout the mission. IMPACT: The instrument automatically reduces voltages when the overcount alarm occurs. Days when SWEPAM-E Overcount Alarm Flagged Intermittent Continuous 1997 0 0 1998 1 (352) 0 1999 0 0 2000 0 3 (196-197,314) 2001 5 (268,309-310,327-328) 0 2002 1 (111) 0 2003 3 (303,306-307) 2 (301-302) 2004 1 (208) 0 2005 4 (017-018,020,135) 0 2006 4 (341-343,347) 0 2007 0 0 2008 0 0 2009 0 0 2010 0 0 2011 1 (217) 0 2012 5 (022-023,025,027,028) 1 (024)