STEREO Weekly Meeting Minutes for 2018-05-15 (Week 20) ANNOUNCEMENTS ------------- * None INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * Behind has transitioned to a monthly schedule to attempt to recover the spacecraft. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 19 (May 7-13) * On day 127 (May 7), during the DSS-55 support for Ahead, turbo decoder lock was lost briefly at 1118z. This anomaly resulted in the loss of one frame of SSR data. * On day 128 (May 8), during the DSS-65 support for Ahead, telemetry lock was lost intermittently at 1701z through 1707z due to rain at the Madrid complex. The SSR pointers were repositioned to minimize data loss. This anomaly resulted in the loss of 6623 frames of real-time telemetry and SSR data, which is equivalent to about 4 minutes at the 240 kbps rate. See DR# M110583 for more information. * On day 130 (May 10), during the DSS-14 support for Ahead, acquisition of signal was 4.1 hours late due to a mechanical issue with antenna pointing. Telemetry was received at 131-0304z for the last 20 minutes of the support which was insufficient time to sweep the uplink and move SSR pointers back. See DR #G119113 for more information. This anomaly resulted in the loss of 4.1 hours of tracking, and real-time telemetry and 4.4 hours of commanding. On the subsequent support, all instrument SSR science pointers were repositioned to minimize data loss. The following is a summary of SSR data loss: - IMPACT starting at 131-1814z (May 11) for 48 minutes. - PLASTIC starting at 131-1815z (May 11) for 48 minutes, 131-1910z for 3 minutes, and 131-2259z for 79 minutes. - SECCHI starting at 130-0054z (May 10) for 12 hours, 131-2305z (May 11) for 19 minutes, and 132-0004z (May 12) for 2 minutes. - SWAVES starting at 131-1639z (May 11) for 2.3 minutes. - Spacecraft housekeeping starting at 130-0055z (May 10) for 25.9 hours, including all attitude information. * On day 133 (May 13), during the DSS-14 support for Ahead, turbo decoder lock was lost briefly at 0158z. This anomaly resulted in the loss of 8 frames of SSR data. * On day 133 (May 13), during the DSS-55 support, turbo decoder lock was lost briefly at 1042z. This anomaly resulted in the loss of 50 frames of SSR data. * On day 127 (May 7), the 7th battery conditioning event was successfully conducted at 1200z on the Ahead spacecraft to redistribute the electrolytes within the nickel hydrogen battery cells. The test results were very consistent with the previous test in 2017. * On day 128 (May 8), the 43rd SECCHI stepped calibration was executed at 1030z for aphelion in the Ahead orbit. This was the 12th SECCHI stepped calibration roll to be conducted without gyro use. * On day 131 (May 11), the IMPACT SSR science partition (#15) on Ahead reached 95% full and began recording only housekeeping data due to the DSS-14 anomaly on day 130 at the following times: - 131-1817z for 1.0 hours - 131-1920z for 0.1 hours * On day 131 (May 11), the PLASTIC SSR science partition (#17) on Ahead reached 95% full and began recording only housekeeping data due to the DSS-14 anomaly on day 130 at the following times: - 131-1818z for 0.9 hours - 131-1918z for 0.1 hours - 131-2236z for 1.7 hours * On day 131 (May 11), the SECCHI SSR science partition (#19) on Ahead reached 100% full at 2251z for 1.5 hours due to the DSS-14 anomaly on day 130. * The average daily science data return for Ahead was 5.8 Gbits during this week. Week 20 (May 14-20) * The 109th momentum dump on Ahead is scheduled for Tuesday, May 15, starting at 20:00 UT. This will be the 28th momentum dump without using the gyros. * Ahead has 13 passes during the week, and overall coverage is nominal. There are eight passes at 720 kbps, four at 240 kbps, and one at 160 kbps. * 1 kHz frequency acquisition recovery tracks for Behind are scheduled for Friday, May 18 (battery), and on Saturday, May 19, and Sunday, May 20 (both carrier). Week 21 (May 21-27) * Ahead reaches aphelion on Thursday, May 24. * The STEREO MOC will be on generator power between Saturday, 10:00 UT, and Sunday, 22:00 UT, May 26-27, for scheduled maintenance. This coincides with Memorial Day weekend. * Ahead has 12 passes during the week, and overall coverage is nominal. There are nine passes at 720 kbps, two at 360 kbps, and one at 240 kbps. * There are no recovery passes for Behind scheduled during the week. Week 22 (May 28-Jun 3) * Monday, May 28, is Memorial Day, which is an APL holiday. * Ahead has 13 passes during the week, and overall coverage is nominal. There are six passes at 720 kbps, four at 360 kbps, one at 240 kbps, and two at 160 kbps. * There are no recovery passes for Behind scheduled during the week. Week 23 (Jun 4-10) * Ahead has 12 passes during the week, and overall coverage is nominal. There are six passes at 720 kbps, four at 360 kbps, one at 240 kbps, and one at 160 kbps. * There are no recovery passes for Behind scheduled during the week. Week 24 (Jun 11-17) * The JPL network will be down for maintenance on Tuesday, Jun 12, between 11:00-15:00 UTC. There are no tracks during this period. * Sunday, Jun 17, marks the date when the Behind spacecraft should resume the capability of 633 bps on the LGA when 3-axis stabilized, with a 2 dB margin. * Ahead has nine tracks during the week, and overall coverage is nominal. There are four tracks at 720 kbps, three at 360 kbps, and two at 240 kbps. * Search pattern tracks to attempt to recover Behind are scheduled for Tuesday, Jun 12 (battery), and on Thursday, Jun 14, and Friday, Jun 15 (both carrier). Week 25 (Jun 18-24) * The 110th momentum dump on Ahead is scheduled for Thursday, Jun 21, with ignition at 20:00 UT. This will be the 29th dump without using the gyros. * Ahead has 11 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, three at 360 kbps, and two at 240 kbps. * There are no recovery passes for Behind during the week. Week 26 (Jun 25-Jul 1) * Ahead has ten tracks during the week, and overall coverage is currently short about 4 hours of 70 meter time between Monday and Tuesday. There are six tracks at 720 kbps, and four at 240 kbps. * There are no recovery passes for Behind during the week. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 20: M May 14 (134) T May 15 (135) Ahead: Momentum dump, 20 UT W May 16 (136) T May 17 (137) F May 18 (138) Behind: Recovery track, DSN 14 (1 kHz, battery) S May 19 (139) Behind: Recovery track, DSN 14 (1 kHz, carrier) S May 20 (140) Behind: Recovery track, DSN 14 (1 kHz, carrier) ------------------------------------------------------------------------------- Scheduled activities for Week 21: M May 21 (141) T May 22 (142) W May 23 (143) T May 24 (144) Ahead: Aphelion F May 25 (145) S May 26 (146) S May 27 (147) ------------------------------------------------------------------------------- Scheduled activities for Week 22: M May 28 (148) Memorial Day T May 29 (149) W May 30 (150) T May 31 (151) F Jun 01 (152) S Jun 02 (153) S Jun 03 (154) ------------------------------------------------------------------------------- Scheduled activities for Week 23: M Jun 04 (155) T Jun 05 (156) W Jun 06 (157) T Jun 07 (158) F Jun 08 (159) S Jun 09 (160) S Jun 10 (161) ------------------------------------------------------------------------------- Scheduled activities for Week 24: M Jun 11 (162) T Jun 12 (163) Behind: Recovery track, DSN 14 (search, battery) W Jun 13 (164) T Jun 14 (165) Behind: Recovery track, DSN 14 (search, carrier) F Jun 15 (166) Behind: Recovery track, DSN 14 (search, carrier) S Jun 16 (167) S Jun 17 (168) ------------------------------------------------------------------------------- Scheduled activities for Week 25: M Jun 18 (169) T Jun 19 (170) W Jun 20 (171) T Jun 21 (172) Ahead: Momentum dump, 20:00 UT F Jun 22 (173) S Jun 23 (174) S Jun 24 (175) ------------------------------------------------------------------------------- Scheduled activities for Week 26: M Jun 25 (176) T Jun 26 (177) W Jun 27 (178) T Jun 28 (179) F Jun 29 (180) S Jun 30 (181) S Jul 01 (182) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2019: * Mar Ahead: Switch downlink rate to 240 kbps for 34 meter * Apr Behind: Switch downlink rate to 240 kbps for 34 meter 2020: * May Behind: Switch downlink rate to 360 kbps for 34 meter * Jun Ahead: Switch downlink rate to 360 kbps for 34 meter * Jun Behind: Switch downlink rate to 480 kbps for 34 meter * Sep Ahead: Switch downlink rate to 480 kbps for 34 meter 2021: * Jul Behind: Switch downlink rate to 720 kbps for 34 meter * Aug Ahead: Switch downlink rate to 720 kbps for 34 meter 2022: 2023: * May 5 Behind: Mercury transit * Jul 17 Behind: Closest approach to Earth * Aug 13 Ahead: Closest approach to Earth 2024: 2025: * Apr 7 Ahead: Mercury transit 2026: 2027: * Feb 1 Behind: Mercury transit 2028: 2029: * Jun 30 Ahead: Mercury transit