STEREO Weekly Meeting Minutes for 2010-02-02 (Week 05) ANNOUNCEMENTS ------------- * The star tracker on Ahead reset on Jan 27 at 07:56 UT, and returned to normal operations at 20:12 UT the same day. See below for details. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 4 * The DSN Central Data Recorder (CDR) returned to normal operations on Monday, Jan 25. The MOC was caught up with the telemetry processing by Wednesday. No SSR data were lost, but processing was delayed by four days between Jan 18 and Jan 26. * Station 55 lost telemetry lock momentarily at 08:23 UT during the Ahead pass on Jan 29. This resulted in the loss of 3 frames. * The star tracker on Ahead reset at 07:56 UT during the station 65 pass on Jan 27. Fault protection kicked in, and tried to promote the star tracker from standby back to Autonomous Attitude Determination (AAD) mode. However, the star tracker was unable to get a solution, and remained in standby mode. This was similar to the problem that the Behind star tracker experienced in December 2007, and was thought to be caused by the presence of a bright object in the field of view. The MOC planned to correct the situation by rolling the spacecraft, but the star tracker was able to get a solution at 20:12 UT to allow promotion to AAD mode, and has stayed in AAD since then. Therefore, the roll maneuver was called off. The spacecraft stayed in fine pointing mode throughout. * The star tracker was in standby mode for 12 hours and 16 minutes. It's estimated that the spacecraft could operate in that mode for several days before negatively affecting the HGA signal. The star tracker is used to update the IMU drift, and active control is done via the gyros. Without the star tracker, the roll angle is expected to drift by about 0.2 degrees/day. HI data can be used to evaluate any roll that might have occurred during the period when the star tracker was offline. * SECCHI loaded software update 5.15 to Behind on Jan 26. This software load fixes a scheduling problem experienced during the recent warm restart. * The average daily SSR downlink volumes for week 3, which were previously unreported because of the CDR problems, were 6.6 gigabits for Ahead, and 5.4 gigabits for Behind. * The average daily SSR downlink volumes for week 4 were 6.5 gigabits for Ahead, and 5.5 gigabits for Behind. Week 5 * SECCHI loaded software update 5.15 to Ahead this morning (Feb 2). * The 21st momentum dump will be carried out on Behind tomorrow (Feb 3), starting at 18:00 UT. Week 6 * Longer than usual gaps between tracks will occur for both spacecraft during the week. To alleviate this, the MOC will move pointers during the tracks for both Ahead and Behind on day 39 (Feb 8), and for Ahead on day 42 (Feb 11). * Behind is scheduled to use the 70 meter station 43 on Feb 14. This track will be carried out at 720 kbps. The pass duration is 7 hours. Week 7 * A 5.4 hour pass using the 70 meter station 43 is scheduled for Behind on Saturday, day 51 (Feb 20). This track will be carried out at 720 kbps. Week 8 * The 12th SECCHI stepped calibration roll on Ahead will be carried out on day 54 (Feb 23), starting at 02:10. This will be the midpoint roll. The system momentum is expected to be 6 N-m-s. Other * PLASTIC reported seeing an error on their GSE for Ahead marked "Error_1553MSG6", and asked for more information about the meaning of the error. SWAVES saw two 1553 errors in succession on Ahead within the last several months. The MOC will check on the PLASTIC error message. * FDF asked about whether STEREO should move from the DE405 ephemeris presently used for STEREO to the more up-to-date DE421 ephemeris. It was decided to stay with the DE405 ephemeris. * SDO is expected to launch on February 9. COORDINATED OBSERVATIONS ------------------------ ------------------------------------------------------------------------------- Scheduled activities for Week 05: M Feb 01 (032) T Feb 02 (033) Ahead: SECCHI software load, 17:00 UT W Feb 03 (034) Behind: Momentum dump, 18:00 UT T Feb 04 (035) F Feb 05 (036) S Feb 06 (037) S Feb 07 (038) ------------------------------------------------------------------------------- Scheduled activities for Week 06: M Feb 08 (039) Both: Move pointers during pass T Feb 09 (040) W Feb 10 (041) T Feb 11 (042) Ahead: Move pointers during pass F Feb 12 (043) S Feb 13 (044) S Feb 14 (045) Behind: 720 kbps downlink on station 43 ------------------------------------------------------------------------------- Scheduled activities for Week 07: M Feb 15 (046) T Feb 16 (047) W Feb 17 (048) T Feb 18 (049) F Feb 19 (050) S Feb 20 (051) Behind: 720 kbps downlink on station 43 S Feb 21 (052) ------------------------------------------------------------------------------- Scheduled activities for Week 08: M Feb 22 (053) T Feb 23 (054) Ahead: SECCHI stepped calibration roll, 2:10 UT W Feb 24 (055) T Feb 25 (056) F Feb 26 (057) S Feb 27 (058) S Feb 28 (059) ------------------------------------------------------------------------------- Upcoming events: 2010: ICAL-001: Jan 11-15, Feb 15-19, Mar 15-19, Apr 12-16, May 3-7 SECCHI Stepped calibration rolls Ahead: Feb 23, May 18, Aug 10, Nov 2 Behind: Apr 6, Jul 13, Oct 12 * Spring (TBD) SUMI sounding rocket launch http://adsabs.harvard.edu/abs/2008AGUSMSP51B..01A * Apr 8,15 EIT shutterless (TBC) * Apr 19 Ahead: Begin 7 hour daily DSN tracks * Apr 26 Ahead: Switch downlink rate to 240 kbps * Jul 8,15 EIT shutterless (TBC) * Jul 11 Total solar eclipse http://eclipse.gsfc.nasa.gov/SEmono/TSE2010/TSE2010.html * Jul 14 Both: HGA calibration * Sep 7 Both: Begin 8 hour daily DSN tracks * Sep 13 Both: Switch downlink rate to 160 kbps * Nov 15 Behind: Switch downlink rate to 120 kbps 2011: * Jan 12 Both: HGA calibration * Feb 6 STEREO spacecraft at 180 degree separation * Mar 18 Messenger - Mercury orbital insertion * Apr 11 Ahead: Switch downlink rate to 120 kbps * Jul 13 Both: HGA calibration * Aug DAWN - Vesta arrival * Sep 19 Behind: Switch downlink rate to 96 kbps * Sep 26 Ahead: Switch downlink rate to 96 kbps 2012: * Jan 11 Both: HGA calibration * May DAWN - Vesta departure * Jul 11 Both: HGA calibration * Aug Both: Switch downlink rate to 30 kbps * Nov 13 Total solar eclipse, south Pacific 2013: * Dec 12 Ahead: Mercury transit 2014: * Apr 29 Behind: Mercury transit 2015: * Feb DAWN - Ceres arrival * Jan 10 - Apr 12 Behind: Spacecraft behind Sun * Feb 17 - Aug 2 Ahead: Spacecraft behind Sun * Jul 23 - Nov 10 Behind: Spacecraft behind Sun * Jul DAWN - End of nominal mission 2016: 2017: 2018: * Mar 5 Ahead: Mercury transit