STEREO Weekly Meeting Minutes for 2010-10-26 (Week 43) ANNOUNCEMENTS ------------- * The STEREO Science Center will be moving from building 26 at Goddard to building 21. The date isn't known yet, but is expected to be sometime after Thanksgiving, or in December. The SSC will be offline for 2-3 days during the move. Science products will still be available at APL. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 42 * On day 291 (Oct 18), during the DSS 65 support for Ahead, turbo decoder lock was lost briefly at 0503z due to a receiver anomaly. This resulted in the loss of several minutes of instrument SSR data. See DR# N106657 for more information. * On day 293 (Oct 20), during the DSS 55 support for Ahead, turbo decoder lock was lost briefly at 0453z. This resulted in the loss of 12 frames of instrument SSR data. See DR# N106658 for more information. * On day 295 (Oct 22), during the DSS 63 support for Ahead, turbo decoder lock was lost briefly at 0511z. This resulted in the loss of eight frames of instrument SSR data. See DR# N106666 for more information. * On day 295 (Oct 22), during the DSS 25 support for Ahead, at 1125z, command uplink was delayed 24 minutes due to transmitter calibration anomaly. The antenna was off pointed to re-calibrate and was back on point at 1153z. At 1433z, the transmitter tripped off-line again. The antenna was off pointed again to re-calibrate and was back on point with the uplink enabled at 1450z. The transmitter tripped offline for a third time at 1513z and was off-line for the remainder of the track. A cable was reseated to clear the anomaly. This resulted in the loss of approximately one hour of instrument SSR data. See DR# G110693, G110694, and G110695 for more information. * On day 291 (Oct 18), the 60 hour soft command loss timer autonomy rule was re-enabled after the completion of the planned RIONet outage at APL. This was performed during the DSS 25 support for Ahead, and the DSS 55 support for Behind. * On day 291 (Oct 18), during the DSS 25 support for Ahead, the telemetry modulation index was changed from 0.78 to 0.83 radians in C&DH RAM for the space weather broadcast only. This was done to lengthen the use of the space weather signal reception at the NOAA stations. The same change will be made on Behind tomorrow (Oct 27). At least one NOAA station has reported a 2 dB improvement from the change. * On day 291 (Oct 18), during the DSS 55 support for Behind, turbo decoder lock was lost briefly at 1817z. This resulted in the loss of several minutes of instrument SSR data. See DR# N106641 for more information. * There was some discussion about whether the recent incidents of loss of turbo decoder lock are due to low signal strength. Some incidents are due to weather, as discussed below. There is also a known anomaly in the turbo decoder software where lock can be lost momentarily, and then reestablished. * On day 292 (Oct 19), during the DSS 26 support for Behind, turbo decoder lock was lost intermittently at 0157z for two minutes due to a combination of a subreflector antenna anomaly and rain at Goldstone. This resulted in the loss of several minutes of instrument SSR data. See DR# N106642 for more information. * On day 293 (Oct 20), during the DSS 26 support for Behind, turbo decoder lock was lost intermittently at 0141z for 15 minutes due to a combination of a subreflector antenna anomaly and rain at Goldstone. This resulted in the loss of approximately 30 minutes of instrument SSR data. See DR# N106643 for more information. * The average daily SSR downlink was 4.9 gigabits on Ahead, and 4.6 gigabits on Behind. Week 43 * Yesterday (Oct 25) was the fourth anniversary of the launch of STEREO. * The station 25 antenna was stored for about 1 hour during the pass on Ahead yesterday (Oct 25). Pointers were backed up, and it's believed that no data were lost. * Turbo decoder lock was lost briefly at 2:00 during the Behind pass yesterday (Oct 25). * The 27th momentum dump will be carried out on Behind on Thursday Oct. 28, starting at 17:30 UT. * There will be a 720 kbps track for Ahead on Wednesday, Oct 27. There will be 14 tracks overall, and coverage will be 2.5 hours over nominal. * There were 720 kbps tracks for Behind on Monday and Tuesday, Oct 25-26. There will be 12 tracks for Behind overall, and coverage will be 1.6 hours over nominal. * IMPACT requests realtime commanding on Behind during this afternoon's pass (Oct 26) starting at 22:30 to diagnose a bit-flip error. They request their full telemetry rate for about half an hour. MOC responds that this should be okay. IMPACT will call into VOICENET. This error was caught through a checksum error. Bit-flip errors have happened several times before. Each time the affected areas of code were not being used--the same may be the case this time. No problems are seen in the beacon telemetry. Week 44 * Ahead will be at aphelion on Nov 6. * Daily savings time in the U.S. ends Nov 7. * Ahead will have 720 kbps tracks on Wednesday, Nov 3, and Saturday, Nov 6. There are 14 passes overall, and coverage is 1.25 hours over nominal. * Behind will have a 720 kbps pass on Saturday, Nov 6. There are 14 passes overall, and coverage is 4.1 hours over nominal. Week 45 * The 15th SECCHI stepped calibration roll will be carried out on Ahead on Tuesday, Nov 9, starting at 08:30 UT. This is the aphelion roll. The system momentum will be about 1 N-m-s. * Ahead has 720 kbps passes on Tuesday, Nov 9, Thursday, Nov 11, and Saturday, Nov 13. There are 14 passes during the week, and overall coverage is 4 hours above nominal. * There are no 720 kbps passes for Behind during the week. There are 12 passes during the week, and overall coverage is 4.4 hours below nominal. In particular, coverage is short 2.5 hours short on Monday, Tuesday, and Wednesday (Nov 8-10). There should be no loss of in situ data. Week 46 * Ahead has 720 kbps passes on Monday, Nov 15, and Friday, Nov 19. There are 14 tracks during the week, and overall coverage is nominal. * Behind has 720 kbps passes on Monday, Nov 15, and Sunday, Nov 21. There are 13 tracks during the week, and overall coverage is 5.3 hours below nominal. In particular, coverage on Wednesday, Nov 17 is 3.2 hours short. There should be no loss of in situ data. Week 47 * Ahead has 720 kbps passes on Tuesday, Nov 24, and Sunday, Nov 28. There are 14 tracks during the week, and overall coverage is nominal. * Behind has 720 kbps passes on Monday, Nov 23, and Friday, Nov 26. There are 14 tracks during the week, and overall coverage is nominal. * Thursday, Nov 25 is Thanksgiving in US. Friday, Nov 26 is also a holiday at APL. COORDINATED OBSERVATIONS ------------------------ ------------------------------------------------------------------------------- Scheduled activities for Week 43: M Oct 25 (298) Behind: 720 kbps downlink on station 43 T Oct 26 (299) Behind: 720 kbps downlink on station 43 Fourth anniversary of STEREO's launch W Oct 27 (300) Ahead: 720 kbps downlink on station 63 Behind: Change modulation index for beacon telemetry T Oct 28 (301) Behind: Momentum dump, 17:30 UT F Oct 29 (302) S Oct 30 (303) S Oct 31 (304) ------------------------------------------------------------------------------- Scheduled activities for Week 44: M Nov 01 (305) T Nov 02 (306) W Nov 03 (307) Ahead: 720 kbps downlink on station 14 T Nov 04 (308) F Nov 05 (309) S Nov 06 (310) Ahead: Aphelion Ahead: 720 kbps downlink on station 14 Behind: 720 kbps downlink on station 43 S Nov 07 (311) Daily savings time ends in U.S. ------------------------------------------------------------------------------- Scheduled activities for Week 45: M Nov 08 (312) T Nov 09 (313) Ahead: SECCHI stepped calibration roll, 08:30 UT Ahead: 720 kbps downlink on station 14 W Nov 10 (314) T Nov 11 (315) Ahead: 720 kbps downlink on station 14 F Nov 12 (316) S Nov 13 (317) Ahead: 720 kbps downlink on station 63 S Nov 14 (318) ------------------------------------------------------------------------------- Scheduled activities for Week 46: M Nov 15 (319) Ahead: 720 kbps downlink on station 14 Behind: 720 kbps downlink on station 43 T Nov 16 (320) W Nov 17 (321) T Nov 18 (322) F Nov 19 (323) Ahead: 720 kbps downlink on station 14 S Nov 20 (324) S Nov 21 (325) Behind: 720 kbps downlink on station 14 ------------------------------------------------------------------------------- Scheduled activities for Week 47: M Nov 22 (326) Behind: 720 kbps downlink on station 63 T Nov 23 (327) Ahead: 720 kbps downlink on station 63 W Nov 24 (328) T Nov 25 (329) US Thanksgiving F Nov 26 (330) Behind: 720 kbps downlink on station 14 S Nov 27 (331) S Nov 28 (332) Ahead: 720 kbps downlink on station 14 ------------------------------------------------------------------------------- Upcoming events: 2011: * Jan 12 Both: HGA calibration * Feb 6 STEREO spacecraft at 180 degree separation * Jun 27 Ahead: Switch downlink rate to 160 kbps * Jun 27 Ahead: End use of 720 kbps on 70 m DSN subnet * Jul 15 Behind: Switch downlink rate to 160 kbps * Jul 15 Behind: End use of 720 kbps on 70 m DSN subnet * Mar 18 Messenger - Mercury orbital insertion * Jul DAWN - Vesta arrival * Jul 13 Both: HGA calibration 2012: * Jan 11 Both: HGA calibration * Jul DAWN - Vesta departure * Jul 11 Both: HGA calibration * Nov 4 Behind: Switch downlink rate to 120 kbps * Nov 13 Total solar eclipse, south Pacific 2013: * May 3 Ahead: Switch downlink rate to 120 kbps * Dec 12 Ahead: Mercury transit 2014: * Jan 20 Behind: End use of 480 kbps on 70 m DSN subnet * Apr 21 Behind: Resume use of 480 kbps on 70 m DSN subnet * Apr 29 Behind: Mercury transit * Oct 15 Behind: End use of 480 kbps on 70 m DSN subnet 2015: * Feb DAWN - Ceres arrival * Jan 20 - Mar 28 (TBC) Behind: Spacecraft behind Sun * Mar 17 - Jul 14 (TBC) Ahead: Spacecraft behind Sun * Jul 2 Behind: Resume use of 480 kbps on 70 m DSN subnet * Aug 25 - Oct 19 (TBC) Behind: Spacecraft behind Sun * Sep 25 Behind: End use of 480 kbps on 70 m DSN subnet * Jul DAWN - End of nominal mission 2016: * Apr 3 Behind: Resume use of 480 kbps on 70 m DSN subnet 2017: * Jul 11 Ahead: Switch downlink rate to 160 kbps * Jul 22 Behind: Switch downlink rate to 160 kbps 2018: * Mar 5 Ahead: Mercury transit