ACE Weekly 01/09/2013 - 01/15/2013 All ACE spacecraft subsystems are performing as expected. ======================================================================== Orbit/Attitude: Type Attitude SK-64 Date 01/15/2013 01/15/2013 DOY 015 2013 015 2013 Thrusters 2R 4R+ 4R- 3A 4A Duration 6:16 min 38.635 sec Start 15:59:50z 17:22:33 Stop 16:06:06z 17:23:12 HGAStart -8.84deg +8.86deg HGAStop +8.86deg +9.07deg SunStart 12.69deg 13.75deg SunStop 13.75deg 13.72deg SpinStart 5.0803rpm 5.0813rpm SpinStop 5.0813rpm 5.0725rpm Nutation 0.19deg 0.11deg Firing 32 pulses Continuous FuelUsed 0.1056lbm 0.1326lbm FuelRemain 116.9536lbm 116.8212lbm FinalSCMass 1351.214lbm 1351.081lbm The next attitude maneuver is scheduled for Tuesday 01/22/2013. ======================================================================== OCRs: DOY 011 (01/11/2013) 2101-2124z & 2346-2354z SIS-053 26 cmds Two more detector strips (M1B HV: 37,39) were disabled. The Matrix bias on Telescope B was raised from 3.73V to 4.26V. And 9 strips were temporarily enabled for monitoring for 2 hours (M1B GND: 46,48 and M1B HV: 2,14,15,18,33,46,62). Currently 45 M1 detector strips have been disabled and 2 have been unusable since launch. ======================================================================== Activities: Data Capture: 99.9997% DOY 006-013 2013 DOY 012 15:48:27-15:55:36 8 seconds lost over a 7 minute period. Data covered by ADC. ======================================================================== Anomalies: DOY 013 01/13/2013 S-ACE-0657 G13-0001 Duplicate data from DSS-27 After the first command (BOT+2minutes), DSS-27 started searching for the high data-rate. However, the spacecraft does not switch to high-rate until after the 3rd command. With DSS-27 searching for high-rate, the MOC decided to send the commands to switch to high-rate before the first command was verified. DSS-27 successfully acquired the high-rate data, but had put a second DCC online while troubleshooting the problem. The voice loop was not enabled. The MOC called the Ops Chief and requested that DSS-27 disable one of the DCCs. IMPACT: Nine minutes of duplicate data. Duplicate data was sent to NOAA SWPC which temporarily impacted SIS data processing. The MOC software did not redump gaps that occurred during this time. 8 seconds of data not captured, but covered by realtime (ADC) data. ======================================================================== Average Sun Angles With Weekly Attitude Maneuvers Dates Avg Sun Avg SEV Sun-SEV (indicates extra s/c tilt) ----------- ------- ------- ---------------------------------- 10/18-10/23 11.0deg 5.1deg 5.9deg 10/23-10/28 9.3deg 3.3deg 6.0deg 10/28-11/06 7.3deg 2.0deg 5.3deg 11/06-11/13 8.4deg 3.8deg 4.6deg 11/13-11/20 10.3deg 6.3deg 4.0deg 11/20-11/27 12.7deg 8.6deg 4.1deg 11/27-12/04 14.9deg 10.1deg 4.8deg 12/04-12/11 16.0deg 10.9deg 5.1deg 12/11-12/18 16.8deg 11.3deg 5.5deg 12/18-12/27 16.5deg 10.7deg 5.8deg 12/27-01/03 16.0deg 9.1deg 6.9deg 01/03-01/08 15.2deg 7.2deg 8.0deg 01/08-01/15 13.8deg 6.0deg 7.8deg The following is background information that will be included in each weekly report. The project has accepted the SWEPAM team proposal to keep the spacecraft at larger sun angles with weekly attitude maneuvers. 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. The maximum sun angle follows the Sun-Earth-Vehicle angle (SEV). The SEV angle is determined by the size/shape of the orbit around L1. When the spacecraft antenna is pointed directly towards earth, the spacecraft's sun angle will be equal to the Sun-Earth-Vehicle angle. With weekly maneuvers, the average sun angle can be kept 4-6deg more than the SEV angle. This results in the spacecraft antenna aspect angle being kept between 5 and 9 degrees and never pointing directly back at earth. For reference, the SWEPAM team prefers sun angles above 13 degrees. With the current size of the L1 orbit, the sun angle will be above 13 degrees for ~45% of the time.