ACE Weekly 11/07/2012 - 11/13/2012 All ACE spacecraft subsystems are performing as expected. ======================================================================== Orbit/Attitude: Type Attitude Date 11/13/2012 DOY 318 2012 Thrusters 2R 4R+ 4R- Duration 19:22 min Start 20:41:42z Stop 21:01:04z HGAStart -7.72deg HGAStop +8.45deg SunStart 6.37deg SunStop 11.81deg SpinStart 5.0807rpm SpinStop 5.0856rpm Nutation 0.15deg Firing 99 pulses FuelUsed 0.2944lbs FuelRemain 118.2604lbs FinalSCMass 1352.520lbs The next attitude maneuver and station keeping #63 are scheduled for Monday 11/19/2012. ======================================================================== OCRs: None ======================================================================== Activities: Data Capture: 100% DOY 309-316 2012 The next WS1 certification test is scheduled for 11/20/2012, which coincides with a day we are unable to get a DSN pass. NOAA SWPC scheduled Air Force support for tracking ACE while NICT (Japan) was down on DOY 314 & 315 and KSWC (Korea) remains down for the past month. This data is routed through the MMOC since the NISN SCD has not yet been upgraded to perform Reed-Solomon decoding. ======================================================================== Anomalies: None ======================================================================== Average Sun Angles With Weekly Attitude Maneuvers Dates Avg SEV Avg Sun Comments ----------- ------- ------- -------------------------------------- 10/18-10/23 5.1deg 11.0deg 10/23-10/28 3.3deg 9.3deg 10/28-11/06 2.0deg 7.3deg sun-sev=5.3 due to 9days between mnvrs 11/06-11/13 3.8deg 8.4deg ACE is moving away from the sun-earth line (larger sun-earth-vehicle angle, SEV) which allows for larger sun angles over the next 5 weeks. After mid-December, the L1 orbit will bring ACE back towards the sun-earth line (smaller SEV angles). 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 sun angle can be kept ~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.