ACE Weekly 10/16/2012 - 10/23/2012 All ACE spacecraft subsystems are performing as expected. ======================================================================== Orbit/Attitude: Type Attitude Attitude Date 10/18/2012 10/23/2012 DOY 292 2012 297 2012 Thrusters 2R 4R+ 4R- 2R 4R+ 4R- Duration 12:05 min 8:08 min Start 18:55:12z 20:14:32z Stop 19:07:17z 20:22:40z HGAStart -4.40deg -7.76deg HGAStop +8.81deg +9.16deg SunStart 9.87deg 11.33deg SunStop 10.80deg 9.93deg SpinStart 5.0711rpm 5.0742rpm SpinStop 5.0740rpm 5.0762rpm Nutation 0.09deg 0.18deg Firing 62 pulses 42 pulses FuelUsed 0.1926lbs 0.1352lbs FuelRemain 119.0148lbs 118.8796lbs FinalSCMass 1353.275lbs 1353.140lbs The next attitude maneuver is scheduled for Tuesday 10/30/2012. We have started weekly Tuesday attitude maneuvers (see MOCR 501 below) to maximize the spacecraft's sun angle. These reports will start including the weekly sun and SEV (Sun-Earth-Vehicle) angle averages. The SEV angle is a good indicator of what the sun angle would have been, with a few caveats too long to list here. The instrument team prefers sun angles above 13 degrees, but that won't be possible for the fraction of time that the SEV angle is less than ~7 degrees. averages from 10/18/2012 to 10/23/2012 SEV Angle 5.1 deg Sun Angle 11.0 deg ======================================================================== OCRs: DOY 292 (10/18/2012) 1947-1955z SIS-048 7 cmds DOY 293 (10/19/2012) 2024-2028z SIS-048 modified 5 cmds Disabled noisy M1B HV strips # 31 & 32 and raise their threshold. There are a total of 512 strips in the M1 and M2 detectors in the two SIS telescopes. So far 38 strips have been disabled since launch and 2 VLSI readout channels were not working at launch. One sis_vstring command was not correctly processed by the instrument on 10/18/2012 causing 2 strips to be excluded. The command sequence was modified and successfully completed on 10/19/2012. See AR S12-0002 below for more information DOY 292 (10/18/2012) MOCR 501 Maximize spacecraft sun angle The SWEPAM team proposal to keep the spacecraft at larger sun angles with weekly attitude maneuvers has been approved. The SWEPAM-Ion instrument has a series of channel electron multipliers (CEMs) and larger sun angles allows more responsive CEMs to measure the solar wind. This especially improves the density measurement from the instrument. ======================================================================== Activities: Data Capture: 100% DOY 288-295 2012 A WS1 certification pass was completed on 10/23/2012. The playback network disconnect problem has been resolved; the issue was a configuration error with NASCOM. There was a short 10 minute delay with the station setup at Beginning of Track. Data forwarding to NOAA was disabled for 30 minutes while testing the MMOC configuration. Nevertheless, all nominal aspects of the pass were successful. ======================================================================== Anomalies: DOY 292 10/18/2012 S-ACE-0653 S12-0002 SIS cmd problem While executing OCR SIS-048, one of the sis_vstring commands was not correctly processed by the instrument. /com.sis_vstring statement="99 98 96 95 90 89 81 80 79 78" This caused a couple of Matrix strips (#78 and 66) to be excluded from the array being written to. The command sequence was resent on the following day with the problem command split into 2 commands. /com.sis_vstring statement="99 98 96 95 90" /com.sis_vstring statement="89 81 80 79 78" It is unknown why the original command was not successfully processed, the data string met the 29 character constraint. But this is the first sis_vstring statement sent with 10 values in the string. IMPACT: The instrument was always in a safe state. A couple of Matrix strips (#78 and 66) were excluded from the array being written to, until the corrected sequence was sent on the following day.