ACE Weekly 11/19/2008 - 11/25/2008 All ACE spacecraft subsystems are performing nominally. ============================================================================ Orbit/Attitude: Type Attitude Date 11/24/2008 DOY 329 2008 Thrusters 2R 4R+ 4R- Duration 14:41 min Start 20:35:03z Stop 20:49:44z HGAStart -7.28deg HGAStop +7.20deg SunStart 14.32deg SunStop 6.26deg Nutation 0.24deg Firing 74 pulses FuelUsed 0.2405lbs FuelRemain 146.5068lbs FinalSCMass 1380.767lbs The next attitude maneuver is scheduled for Wednesday 12/03/2008. =========================================================================== OCRs: DOY 325 (11/20/2008) 2000-2030z GND-195 A Contingency Exercise is performed annually to confirm that the spacecraft can be commanded from a software backup. This exercise runs the TPOCC software and sends a NO_OP command from a workstation with software from a backup archive. This was last performed 11/19/2007 (GND-190). ============================================================================ Activities: Data Capture: 100% DOY 321-328 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. From Wednesday DOY 324 through Friday DOY 333, ACE has only had southern hemisphere ranging. The reason is that DSS-46 is readily available but the other sites have been utilized by other missions. With maneuvers on DOY 319, 329 and 338, there will still be range data from other DSN sites inbetween these maneuvers. However, the team will work to avoid having such a long stretch of range data from only one site in the future. ============================================================================ Anomalies: Update AR#S08-0004 SEPICA is operating as expected after switching to Standby Mode on 11/11/2008, power cycling on 11/13/2008 and restoring configuration on 11/18/2008. However, there continues to be a lack of isobutane gas which means the instrument cannot do mass or charge state composition measurements. The Fan 3 valve (the last open valve) has remained closed since 02/04/2005. The valves have opened spontaneously in the past and could do so again in the future. DOY 324 11/19/2008 S-ACE-0381 G08-0115 DSS-46 Intermittent Data Loss DSS-46 receiver (MFR) had intermittent data loss from 1915-1920z. The station switched to ATS2 which resolved the problem. Further intermittent data loss occurred from 2050-2058z. The station increased the RF Loop Bandwidth to 750Hz which resolved the problem. DR#C106638 IMPACT: Data redumps were completed on the following pass. DOY 329 11/24/2008 S-ACE-0382 G08-0116 DSS-46 FCLTU SLE Problems DSS-46 was not radiating commands at Beginning Of Track (BOT). The station toggled command system several times without success. The station then reloaded the desktop which resolved the problems. DR#C106648 IMPACT: Activities delayed 30 minutes. DOY 329 11/24/2008 S-ACE-0383 G08-0117 C&C/ROBOTT Froze & Re-executed The ACE MOC automation software (ROBOTT/C&C) froze during the DSS-46 commanding problems (AR#G08-0116). The TPOCC software successfully completed the initial commanding sequence after the DSS-46 problems were resolved. However, after the reboot of the MOC automation software, ROBOTT/C&C re-executed the initial commanding sequence. IMPACT: Fortunately, the FOT had designed the procedures to handle the contingency of double execution. Data playback commands were skipped during the second execution of the procedure.