ACE Weekly 01/10/2012 - 01/16/2012 All ACE spacecraft subsystems are performing as expected. ======================================================================== Orbit/Attitude: Type Attitude Date 01/12/2012 DOY 012 2012 Thrusters 2R 4R+ 4R- Duration 12:27 min Start 17:11:24z Stop 17:23:51z HGAStart -4.83deg HGAStop +7.86deg SunStart 6.49deg SunStop 16.44deg SpinStart 5.0407rpm SpinStop 5.0443rpm Nutation 0.18deg Firing 63 pulses FuelUsed 0.2018lbs FuelRemain 124.2648lbs FinalSCMass 1358.525lbs The next attitude maneuver is scheduled for Monday 01/30/2012. ======================================================================= OCRs: A proposal (MOCR 387) has been submitted to allow the spacecraft to violate the 4 degree sun constraint and drift (no nutation) to a sun angle of 2 degrees during the February 2012 Solar Exclusion Zone (SEZ) transit. This allows the spacecraft antenna to be pointing more directly towards earth and reduce the risk of data loss. The 4 degree sun constraint reads as follows: "Operation at a sun angle (angle between spacecraft +Z axis and sun) much less than 4 deg will cause: loss of sun pulse or cause multiple sun pulses per spin to be observed (which makes the apparent spin rate appear faster than it really is). Multiple sun pulses per spin can occur at small spin axis/S/C-sunline angles because nutation causes the spin axis to rotate about the system angular momentum vector changing the rate at which the sun is moving about the geometric Z-axis." During the November 2011 solar exclusion zone transit, the sun angle drifted below 4 degrees (11/15/2011 through 11/20/2011) with the minimum sun angle of 3.1 degrees on 11/17/2011. There was no impact to the sun pulse timing. On DOY 250 1997, 13 days into the mission, an orbit shaping maneuver dropped the sun angle to 2.3 degrees. The sun pulse timing was impacted due to nutation (up to +/-0.5 seconds in the 12 second rotation), but the sun pulse still occurred at this small sun angle. ======================================================================== Activities: Data Capture: 100% DOY 008-015 2012 ======================================================================== Anomalies: None