ACE Weekly 05/17/2011 - 05/23/2011 All ACE spacecraft subsystems are performing nominally. ======================================================================== Orbit/Attitude: Type Attitude Date 05/17/2011 DOY 137 2011 Thrusters 2R 4R+ 4R- Duration 14:26 min Start 15:39:31z Stop 15:53:57z HGAStart -8.20deg HGAStop +7.54deg SunStart 9.56deg SunStop 7.46deg SpinStart 5.0862rpm SpinStop 5.0901rpm Nutation 0.13deg Firing 74 pulses FuelUsed 0.2319lbs FuelRemain 128.8988lbs FinalSCMass 1363.159lbs The next attitude maneuver is scheduled for Thursday 05/26/2011. ======================================================================= OCRs: None ======================================================================== Activities: Data Capture: 100% DOY 135-142 2011 Update on NOAA Space Weather Prediction Center tracking of ACE DLR (Germany) started tracking ACE again on May 18. The closest Sun-Earth-Vehicle (SEV) angle was on May 19 with 1.41 degrees and DLR did not have problems. However, NICT (Japan) has been down since Tuesday May 17 due to failure of their air conditioner. There are problems getting a replacement due to ongoing problems from the March 11, 2011 earthquake. At best, it'll be 1-2 months before NICT's antenna is back up. This causes a ~4.5 hour gap (2330-0400) between coverage from Wallops (WCDA) and Germany (DLR). NOAA SWPC is investigating using other antennas including the Near Earth Network (NEN) Alaska Satellite Facility (ASF) and the NOAA's Gilmore Creek Facility. Note, the NOAA SWPC operations are separate from the Goddard flight operations, but this information is worth noting and therefore included in this weekly report. Update on SEPICA Temperatures. The following is an updated table with instrument deck temperatures with SEPICA ON and OFF. The SEPICA ON temperatures were averaged over 44 days and the SEPICA OFF temperatures were averaged over 25 days. The days were picked to match the same sun distance and sun angle. There will be some error in these numbers and other affects, including the continual insulation degradation. However, we expect that these numbers are close to the actual temperature changes due to SEPICA being powered off. ON OFF Diff SEPICA_IF_T 36.1 25.2 10.9 SEPICA_BASEPL_T 31.8 23.0 8.7 CNTR_IDECK_T 26.4 22.6 3.8 ULEIS_IDECK_CNTR 23.1 19.9 3.2 YP_ANTBASE_T 18.0 15.7 2.4 YP_XM_IDECK_T 16.0 13.7 2.3 S3DPU_PS_A_T 41.7 39.8 1.9 S3DPU_PS_B_T 40.4 38.6 1.8 SWPE_IF_T 13.0 11.4 1.6 SWPE_INT_T 18.5 16.9 1.6 ULEIS_ANLG_E_T 28.9 27.2 1.6 MAG_PCTEMP 40.4 38.4 1.9 MFI_IDECK_T 21.2 19.6 1.6 XP_YP_IDECK_T 10.1 8.7 1.4 AE_IDECK_T 22.5 21.3 1.2 ULEIS_DPU_T 23.6 22.5 1.0 SIS_IDECK_EDGE 12.0 11.4 0.7 XP_EDGE_IDECK_T 9.8 9.2 0.6 ULEIS_SCOPE_T 6.1 5.5 0.6 ULEIS_IF_T 3.3 2.7 0.6 SWICS_IF_T 6.3 5.8 0.5 YP_XM_TOP_CNTR_T 11.1 10.1 0.9 SIS_IF_T 24.4 24.6 -0.2 SEPICA ON DOY 111-115, 120-136 and 234-257 Average Sun Distance 149404225.0 km Average Sun Angle 7.9 deg SEPICA OFF DOY 111-136 2011 Average Sun Distance 149378062.3 km Average Sun Angle 7.8 deg ======================================================================== Anomalies: DOY 140 05/20/2011 S-ACE-0610 G11-0037 SLE Command Negative DSN has a known issue that their command system occasionally rejects commands via SLE. When this occurs, the MMOC needs to manually disconnect and reconnect SLE FCLTU. The command negative problem last occurred on 04/29/2011. (AR#G11-0034). IMPACT: Manual intervention required for commanding. DOY 142 05/22/2011 S-ACE-0611 G11-0038 D27 Power Outage The DSN ground station was experiencing a power outage at ACE's Beginning Of Track (1455z). Power was restored at 1605z and telemetry was online at 1739z. The MMOC automation initiated commanding. However, no VC2 (playback) data was received in the MMOC and no data was available at DSN's DCD. DR#G111540 IMPACT: Manual intervention on Monday (DOY 143) to redump the data missing from DOY 142. It will take ~3 days to catch up on the SSR playback. A 31 second gap will occur on DOY 144 due to the expected SSR failover.