ACE Weekly 10/15/2008 - 10/21/2008 All ACE spacecraft subsystems are performing nominally. ============================================================================ Orbit/Attitude: No maneuvers were performed this week. The next attitude maneuver is scheduled for Friday 10/31/2008. =========================================================================== OCRs: None ============================================================================ Activities: Data Capture: 100% DOY 286-293 2008 The risk of data loss has again increased for the October-February time frame. Several missions are competing for the same antenna time (daylight hours). If there are problems with the passes, it may not be possible to acquire additional DSN time. For more information refer to 10/14/2008 weekly. New requirements on FDF ephemeris generation will need to be negotiated. DSN implemented SPSv1.2 on 10/9/2008. The new SPS requires a 26-week scheduling grade ephemeris for viewperiod generation. This will be in addition to the 12-week predict grade ephemeris that is currently delivered. (See AR#G08-0099 below) ============================================================================ Anomalies: DOY 289 10/15/2008 S-ACE-0360 G08-0095 DSS-46 SLE Bind Broken At Beginning Of Track (BOT), the first command (TIME_BIN_LOAD) was not transmitted to the spacecraft and FCLTU Bind was broken. The ACE MOC SLE software successfully rebinded, but the bind was broken for each subsequent command retransmission. The FOT requested that DSS-46 switch the uplink system from Operate to Halt and back to Operate. The first command was successful transmitted after 10 minutes. DR#C106578 attributes the problem to DSS-46 TCP time. IMPACT: Manual intervention required. Activities delayed 10 minutes. DOY 289 10/15/2008 S-ACE-0361 G08-0096 DSS-46 TCP configuration ACE is commanded from low-rate (498bps) to high-rate (87648bps) at the beginning of every support. This requires the station operator to manually reconfigure the TCP (Telemetry Control Processor). A brief misconfiguration was quickly corrected by the station operator. DR#C106579 IMPACT: Minimal. 3 minute telemetry outage. DOY 290 10/16/2008 S-ACE-0362 G08-0097 DSS-27 Transmitter Problems DSS-27 transmitter calibration problems resulted in a lost interface to the LMP (Link Monitor Processor). An operator travelled to the antenna to perform the resets. DR#G108901 IMPACT: Activities delayed 8 minutes. DOY 294 10/20/2008 S-ACE-0364 G08-0099 New DSN/SPS/FDF requirements This anomaly report is to document that DSN SPSv1.2 was implemented before new requirements on FDF ephemeris generation were negotiated. IMPACT: Viewperiod generation will be based on the ephemeris created on 07/09/2008. Even though there have been 8 attitude maneuvers, 1 spin maneuver and 1 station keeping maneuver since July, there is only a few seconds difference in viewperiods. All of this is more of a problem with Earth orbiters as opposed to L1 missions. DOY 294 10/20/2008 S-ACE-0365 G08-0100 FDF Viewperiod Masks for D45/D65 FDF provides their own viewperiod generation that is used by the FOT and scheduling team. FDF recently added DSS-45 and DSS-65, however, the RISE and SET times differ significantly from DSN's viewperiod files. FDF has been asked to verify with DSN that they are using the correct horizon masks. IMPACT: ACE has only scheduled one pass every ~2 months since the S-Band transmitters went operational; DSS-45 and DSS-65 are already heavily used. Fixing this problem, however, will avoid out-of-view problems when the antennas are scheduled.