ACE Weekly 11/26/2008 - 12/02/2008 All ACE spacecraft subsystems are performing nominally. ============================================================================ Orbit/Attitude: No maneuvers were completed this week. The next attitude maneuver is scheduled for Wednesday 12/03/2008. =========================================================================== OCRs: None ============================================================================ Activities: Data Capture: 100% DOY 328-335 2008 There is a higher than normal risk of data loss from October 2008 through February 2009. If there are problems with the passes, it may not be possible to acquire additional DSN time. This higher-risk period has been occurring every winter for the past couple of years. For more information refer to 10/14/2008 weekly. ============================================================================ Anomalies: DOY 329 11/24/2008 S-ACE-0384 G08-0117 AC2WS1 Operating System Version When the AC2WS1 hard drive failed (10/31/2008 G08-0104), the software restore was not finished. The operating software (e.g. /bin) was an earlier version. AC2WS1 is on the backup string; it took 2 weeks to discover and 1 week to troubleshoot. The System Administrators had been called to another mission before the restore had been completed. IMPACT: The TPOCC software did not work with this version of the operating software. However, no MOC failovers were required during this time. DOY 331 11/26/2008 S-ACE-0385 G08-0118 No Lock on Receiver B When DSS-46 established the uplink at BOT, the spacecraft RCVR B did not lock on the uplink. This occurs 1-3 times a year. Since RCVR A is transmitting, DSN sweeps the uplink to lock on RCVR A. During this sweep, RCVR B also locks on the uplink automatically. There is no problem with the spacecraft, but the FOT tracks these occurrences with anomaly reports for trending purposes. This last occurred on 12/09/2007 (AR#G07-0102) IMPACT: Minimal. C&DH B timers were reset on the next day (DOY 332). DOY 333 11/28/2008 S-ACE-0386 G08-0119 DSS-46 CMD/SLE Problems DSS-46 was unable to configure for SLE commanding at Beginning Of Track (BOT). The station rebooted and reloaded the equipment several times. The problem was resolved when the station stopped and then re-established the uplink using link 2. DR#C106658 IMPACT: Activities delayed 1 hour 40 minutes. SSR playback completed on the following pass. Note, FOT intervention not required since the ACE MOC SLE software automatically attempts to reconnect once a minute. DOY 335 11/30/2008 S-ACE-0387 G08-0120 DSS-46 CMD/SLE Problems DSS-46 was unable to configure for SLE commanding at Beginning Of Track (BOT). The station rebooted and reloaded the equipment several times. The problem was resolved when the station rebooted MCP (Monitor Control Processor). DR#C106666 IMPACT: Activities delayed 40 minutes. The SSR playback was completed on the following pass. DOY 336 12/01/2008 S-ACE-0388 G08-0121 Incorrect Nutation Calculation The nutation provided in the maneuver summaries (starting 09/20/2007) is calculated using an FOT tool called mansum. The calculation incorrectly included a factor of 2. If the nutation was reported as 0.24 degrees, it was actually 0.12 degrees. MOCR 1383 will correct this problem. IMPACT: Actual nutation is smaller than reported by a factor of 2. DOY 336 12/01/2008 S-ACE-0389 G08-0122 DSN Tracking Data To FDF FDF did not receive tracking data from 11/19/2008 through 11/30/2008 while JPL was using a backup track server (trk4). A query script on the backup server did not use the correct entry in the SCAP table (Security Content Automation Protocol). The query script was updated on 12/1/2008. The SCAP tables had been updated 09/15/2008. The WIND mission tracking data was also affected. IMPACT: JPL will retransmit the lost tracking data to FDF. FDF was still able to perform ACE orbit determination (OD) on 11/21/2008. The problem was resolved before the next scheduled ACE OD on 12/02/2008.