ACE Weekly 09/16/2009 - 09/22/2009 All ACE spacecraft subsystems are performing nominally. ======================================================================== Orbit/Attitude: No maneuvers were completed this week. The next attitude maneuver and Station-Keeping #52 are scheduled for Thursday 09/24/2009. ======================================================================= OCRs: None ======================================================================== Activities: DOY 259 09/16/2009 - Multi-Mission Operations Center (MMOC) Test The MMOC was able to command to ACE using DSS-27. The MMOC received ACE realtime data. There were no problems when data forwarding was configured for just NOAA Space Weather. The ACE Science Center (ASC) system has not yet been configured to receive data from the MMOC computers. During commanding, the TwosComplementChecksum was not populated in the READ_S0 command sent to the spacecraft using the new MMOC mission software (ITOS). The command had been successfully built in previous releases of ITOS, but was not correct for the version of ITOS used during the test. The SSR ignored the command and flagged the error (AR#S09-0006). Another ITOS delivery is scheduled for 09/28/2009. Data Capture: 100% DOY 256-263 2009 DSN availability continues to be limited with the increased LCROSS usage and the DSS-24/DSS-54 downtime. SSR playback was finally caught up on DOY 264. Unfortunately, there was no pass on DOY 265. SSR Playback will continue to not be finished until the following pass. There is a scenario that will cause data loss with the automated SSR procedures. If the data to be dumped from the previous pass exceeds the length the next pass (+40 minutes for setup and SSR swap); then the SSR procedures will not dump all of the data carried over from the previous pass. That scenario will occur on DOY 266 (88 minutes leftover from the previous dump and the next pass is only 95 minutes). The pass on DOY 266 will be taken manually to avoid the ~8 hours of data loss. Note that ACE passes are usually 210 minutes long, but have been shortened due to LCROSS and limited DSN availability. Another consequence of the limited DSN availability is the reduced ranging data following the station keeping maneuver on DOY 267. After a station keeping maneuver, 3-4 1-hour range passes are taken so that FDF can determine the results of the maneuver. There are no additional ranging passes for this station keeping maneuver. The daily tracking passes have been kept as ranging supports; but this will delay SSR playback from being completed. Also, there will not be any southern hemisphere ranging for 7 days following the station keeping maneuver. ======================================================================== Anomalies: DOY 259 09/16/2009 S-ACE-0460 S09-0006 Invalid Checksum in READ_S0 The READ_S0 command was sent to the spacecraft from ITOS 803-0 in the MMOC during a test. The command did not have the SSR checksum calculated. /com.read_s0 ssrb, offset=0, size=5242880 sent: 0d 0a 000c 4c11 00000000 00500000 0000 correct: 0d 0a 000c 4c11 00000000 00500000 b39f Impact: The SSR ignored the command and flagged the error (LAST_COM_INV_B, ERROR_CT_B and SYS_ERR_CODES_B).