ACE Weekly 11/14/2007 - 11/20/2007 All ACE spacecraft subsystems are performing nominally. ============================================================================ Orbit/Attitude: The attitude maneuver was postponed from Thursday to Friday due to Anomaly G07-0096. Type Attitude Date 11/16/2007 DOY 320 2007 Thrusters 2R 4R+ 4R- Duration 11:45 min Start 13:14:40z Stop 13:26:25z HGAStart -7.71deg HGAStop 6.54deg SunStart 15.67deg SunStop 5.74deg Nutation 0.30deg Firing 60 pulses FuelUsed 0.1988lbs FuelRemain 153.5604lbs FinalSCMass 1387.820lbs The next attitude maneuver is scheduled for Tuesday, 11/27/2007. ============================================================================ OCRs: None ============================================================================ Activities: Space Link Extension (SLE) Testing status (F-CLTU) The Friday 11/16/2007 DSS-46 test was successful. The DSN Ground Receipt Time problem has been resolved. The FOT also tested the SLE feature where commands are transmitted at specified times (aka Command Timing). The DSN F-CLTU service worked correctly, commands that were tagged for an hour in the future were not sent until the prescribed time. However, the FOT will keep this feature disabled since it introduces a risk if the local workstation system time is not correct. The transition to F-CLTU SLE has been targeted for Thursday 11/29/2007. 34m HEF S-Band Transmitter Testing Status The Thursday 11/15/2007 DSS-45 test was successful. Telemetry was acquired at all 3 bit rates. The ACE MOC successfully binded and commanded to the spacecraft. And the GSFC Metric Tracking Data Evaluation (MTDE) group received good Range and Doppler data. The uplink signal strength measured by the spacecraft was Hi-Gain Antenna = -99 dBm BroadBeam Antenna = -111 dBm This signal strength is more than adequate and is comparable to DSS-27 (another 34m antenna with 200W transmitter). No further DSS-45 tests are scheduled. DSS-65 tests have been scheduled as follows Date DOY Station Test Mon 12/03 337 DSS-65 S-Band XMTR, SLE and range data Wed 12/05 339 DSS-65 S-Band XMTR, SLE and range data ============================================================================ Anomalies: DOY 316 11/12/2007 S-ACE-0242 S07-0010 S3DPU_I Limit Violation S3DPU current (S3DPU_I) briefly violated the red high limit (RH > 145mA). The S3DPU Idle Counter (SSDIDLECTR) was at 52. 2007-316-21:59:36 - 21:59:37 150.528-153.664mA IMPACT: The last brief S3DPU_I violation was 2007-270-16:36:48. DOY 318 11/14/2007 S-ACE-0243 G07-0095 DSS-27 Incorrect Bit Rate At BOT, DSS-27 configured for high-rate data (87648bps), but the spacecraft was still at low-rate data (498bps). No telemetry was available and the MOC automation software was waiting for telemetry before commanding the spacecraft to high-rate. The MOC contacted the station and asked that the station configure for low-rate data which kicked off the MOC automation software. IMPACT: The BOT bit rate change was changed from automatic (pre-loaded) to manual (real-time cmd) as part of the 2004 transition to automation. This simplified the MOC automation, increased scheduling flexibility and reduced outages to NOAA. The consequence is that the DSN station must configure for the 87648bps bit rate after the real-time commands are sent. This problem occurs 1-3 times each year. DOY 318 11/14/2007 S-ACE-0244 G07-0096 Maneuver Planning HardDrive Fail The hard drive for the maneuver planning PC failed on the day before an attitude maneuver (DOY 319). The FOT used a functionally minimal backup to plan the maneuver, but nevertheless postponed the maneuver for a day. The SysAdmins recovered a significant portion of the hard drive and restored the maneuver planning PC at the end of DOY 319. The maneuver was planned with the restored maneuver planning PC which gave the same results as the backup. The maneuver was successfully executed on DOY 320 (Friday 11/16/2007). IMPACT: No angle constraints were violated by waiting an additional day (HGA=-7.71deg Sun=15.67deg). The same target was used for the maneuver and no additional fuel was consumed. All future maneuvers will be executed as previously planned. DOY 324 11/20/2007 S-ACE-0245 G07-0097 DSS-46 S-Band Exciter Station was unable to obtain lock for a "Range Only" pass until the station switched to SBE2. Range data delayed 30 minutes. Station continued uplink for 30minutes after End Of Track (EOT) IMPACT: There are 5 other southern hemisphere range passes between the attitude maneuver on 11/16/2007 and 11/27/2007. Orbit Determination should have sufficient range data. And it would have been better if the station terminated the uplink at the scheduled time.