ACE Weekly 01/04/2013 - 01/08/2013 All ACE spacecraft subsystems are performing as expected. This report covers 5 days. Weekly maneuvers & reports had shifted to Thursdays over the holidays and are now back on Tuesdays. ======================================================================== Orbit/Attitude: Type Attitude Date 01/08/2013 DOY 008 2013 Thrusters 2R 4R+ 4R- Duration 5:06 min Start 18:53:12z Stop 18:58:18z HGAStart -8.90deg HGAStop +8.99deg SunStart 14.07deg SunStop 15.45deg SpinStart 5.0794rpm SpinStop 5.0805rpm Nutation 0.18deg Firing 26 pulses FuelUsed 0.0876lbs FuelRemain 117.0592lbs FinalSCMass 1351.319lbs The next attitude maneuver and station-keeping #64 are scheduled for Tuesday 01/15/2013. We have had one southern hemisphere ranging pass between the previous maneuver (1/3/2013) and this maneuver (1/8/2013). However, there will be no more southern hemisphere ranging before the station keeping maneuver next week. Southern Hemisphere ranging will be more available (2 per week) after the station keeping maneuver. ======================================================================== OCRs: None ======================================================================== Activities: Data Capture: 100% DOY 365-006 2013 ======================================================================== Anomalies: None ======================================================================== 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 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.