ACE Weekly 07/12/02 - 07/18/02 All ACE spacecraft subsystems are performing nominally. An attitude maneuvers was executed on 07/12/02. The next attitude maneuver is scheduled for 07/30/02. ============================================================================ Ongoing Activity: The engineering test to determine the new HGA constraint is continuing. The current constraint is 6.0 deg., with current tests reaching 6.5 degrees. The attitude maneuver on 7/12/02 targeted +6.5 deg. The FOT has been monitoring the Signal Strength, the MFR AGC levels, and the Signal-to-Noise Ratios(SNR). The drop in RF levels from an HGA angle of 0 deg to 6 deg has been approximately 3dB. There has been no loss of telemetry due to the increased HGA angles. Once all analysis has been completed, the new HGA constraint will be determined. The following HGA angles and range values are from FDF. Man Date Pre Man Post Man Earth-ACE Range 03/28/02 -4.58 deg +4.38 1408287 km 04/04/02 -4.35 +4.50 1414808 04/11/01 -5.09 +3.79 1428491 04/18/02 -5.16 +3.85 1440512 04/26/02 -5.77 +5.56 1455949 05/06/02 -5.72 +5.43 1493008 05/17/02 -5.81 +5.31 1527979 05/28/02 -4.34 +4.88 1550263 06/06/02 -2.38 +5.96 1576064 06/20/02 -6.57 -3.66 1590405 06/26/02 -6.43 +5.94 1592458 07/12/02 -6.5 +6.5 ============================================================================ Stationkeeping Maneuver Information from FDF We have a stationkeeping maneuver (SK-26) scheduled for Tuesday, July 30, to be followed by an attitude reorientation. The delta-V direction will be Sunward, requiring the aft-end canted axials 3A and 4A. Based on the latest OD, halo re-targeting results show a delta-V of 0.908 m/sec is needed. Preliminary finite burn modeling predicts a burn duration of 162.7 sec (2.7 min) and a fuel usage of 0.634 lbm (0.288 kg). Also, we expect to see a spin rate drop of around 0.037 rpm from this burn (no spin correction maneuver will be necessary). The required spin range is 4.90 to 5.10 rpm. Since we're at right about 5.0 at the moment, we'll end up at about 4.96 rpm, well within the tolerances by 0.06 rpm. ============================================================================ TPOCC Release 5.2 Testing Status Testing of TPOCC Release 5.2 on String 3 is completed. No major problems were identified. ============================================================================ Anomalies: DOY 02198 (07/17/2002) - ACE Anomaly #G02-0086 No MFR Data from D27 Throughout the pass, no MFR data was populated in the monitor blocks from D27. MFR data is being used in the ongoing analysis of increasing the HGA angle out to 6.5 degrees. IMPACT: Degraded analysis of HGA angle. *********************************** Glen A. Miller Honeywell Technical Services Inc. ACE Flight Operations Team Goddard Space Flight Center Bldg. 14, Rm. W10A Mail Stop 428.2 Greenbelt, MD 20771 Office: 301-286-7071 Fax: 301-286-1729 ***********************************