STEREO Weekly Meeting Minutes for 2008-01-02 (Week 1) ANNOUNCEMENTS ------------- * The second SECCHI campaign runs from January 7-20. Details are below. INSTRUMENT AND SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal, except that the Ahead spececraft is currently operating on IMU #2. * The star tracker on Behind suffered an anomaly on December 21, but has since been restored to normal operation. See details below. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 51, 2007 * The 10th momentum dump was performed on Ahead on day 354 (Dec 20). Playback was stopped during the momentum dump, which resulting in not completing the 2nd playback of PLASTIC telemetry. Because of this, the pointers were not reset, and PLASTIC lost about 12.5 hours of data starting at 02:34 UT on day 355 (Dec 21). * On day 353 (Dec 19), station 55 was unable to bring up the command link with Behind because of a temperature alarm. Two-way communication was achieved about 1 hour and 49 minutes into the track. This resulted in a loss of about 10 minutes of SECCHI data. * On day 354 (Dec 20), station 45 was down for most of the track. Some telemetry did come down at the end of the track. An autonomy rule correctly reset the pointers and no SSR data was lost. * The average daily downlink was 6.9 gigabits on Ahead, and 5.9 gigabits on Behind. * On day 355 (Dec 21) the star tracker on Behind went into INIT mode at 10:10 UT. Autonomy rules automatically promoted it to STANDBY mode, and then tried to put it into its normal operating (AAD) mode, but it wouldn't stay in that mode. After 4 hours (14:10 UT) another autonomy rule automatically switched to the low gain antenna at an emergency rate of 11 bps. Since this happened during a track, Mission Ops commanded the rate to 633 bps and started reviewing black box and star tracker data dumps. At all times the spacecraft remained sun pointed, with the instruments taking data. On day 357 (Dec 23) the star tracker returned to AAD mode and remained there. It was decided to take a cautious approach, disabling the star tracker between tracks and only enabling it during the tracks. Also, the spacecraft was switched between the low gain antenna between tracks and the high gain antenna during tracks. On Christmas day the link margin only permitted a rate of 480 kbps; on all other days 720 kbps was used. Because of the extra overhead in switching between modes, about 40% of the SECCHI data was lost. Double playback of the insitu data was cancelled during this period to minimize the amount of SECCHI data lost. Normal operations was resumed on Thursday, December 27. * The cause of the star tracker problems is not yet understood. A meeting was held with the manufacturer on Wednesday, Dec 26. Data is being sent to the manufacturer, and they will examine it when they reopen next week. * Spacecraft roll knowledge is degraded during the period when the star tracker was disabled or out of AAD mode, with a possible error of 0.2-0.4 degrees. * SECCHI requests the start and stop times of the high rate telemetry during the manual operations period. Week 52 * On day 358 (Dec 24), the transmitter on station 26 failed for the Ahead track. Station 24 was used instead. * The average daily downlink ws 7.5 gigabits on Ahead, and 4.9 gigabits on Behind. Week 1, 2008 * A SECCHI stepped calibration roll will be carried out on Ahead tomorrow, January 3. The maneuver starts at 07:10 UT and lasts 3 hours. Week 2 * The second SECCHI campaign runs from January 7-20. This campaign consists of two tracks per day for each spacecraft, with the second track lasting for 3 hours and bringing down only SECCHI data. COORDINATED OBSERVATIONS ------------------------ ------------------------------------------------------------------------------- Scheduled activities for Week 01: M Dec 31 (365) T Jan 01 (001) W Jan 02 (002) T Jan 03 (003) Ahead: SECCHI Stepped Calibration Roll, 07:10 UT F Jan 04 (004) S Jan 05 (005) S Jan 06 (006) ------------------------------------------------------------------------------- Scheduled activities for Week 02: M Jan 07 (007) Start of second SECCHI campaign T Jan 08 (008) W Jan 09 (009) T Jan 10 (010) F Jan 11 (011) S Jan 12 (012) S Jan 13 (013) Notes: * Jan 7-20 SECCHI campaign ------------------------------------------------------------------------------- Scheduled activities for Week 03: M Jan 14 (014) Messenger - Mercury fly-by T Jan 15 (015) W Jan 16 (016) T Jan 17 (017) F Jan 18 (018) S Jan 19 (019) S Jan 20 (020) End of SECCHI campaign Notes: * Jan 7-20 SECCHI campaign ------------------------------------------------------------------------------- Upcoming events: 2008: SECCHI Stepped calibration rolls Ahead: Apr 1, Jun 24, Sep 23, Dec 16 Behind: Feb 19, May 20, Aug 26, Dec 2 * Dec 2007-May 2008 Ulysses quadrature http://stereo-ssc.nascom.nasa.gov/plans/UlyLocation2006-2014_v1.pdf * Mar 20 - Apr 16 Whole Heliosphere Interval http://ihy2007.org/WHI/targeted_plans.shtml * Apr 10-16 JOP 204, Energetics and dynamics of the quiet Sun * Apr 21 - May 16 SUMER campaign * Oct 6 Messenger - Mercury fly-by