STEREO Weekly Meeting Minutes for 2017-05-23 (Week 21) ANNOUNCEMENTS ------------- * None. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * Attempts to recover Behind have transitioned back to a monthly schedule. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 20 (May 15-21) * On day 135 (May 15), during the DSS-26 support for Ahead, the command uplink was established late at 2012z due to a power anomaly at the station. SSR pointers were repositioned during the track to minimize data loss. All SSR data was recovered. See DR #G118131 for more information. * On day 136 (May 16), during the DSS-14 support for Ahead, turbo decoder lock was lost briefly at 0248z and 0300z. This anomaly resulted in the loss of five frames of SSR data. See DR #G118137 for more information. * On day 139 (May 19), during the DSS-43 support for Ahead, telemetry lock was lost intermittently between 0617z and 0728z due to heavy rain at the Canberra complex. This anomaly resulted in the loss of 119,135 frames of real-time and SSR data. SSR pointers were repositioned on the next support and all SSR data were recovered. See DR# C112690 for more information. * On day 139 (May 19), during the DSS-14 support for Ahead, turbo decoder lock was lost intermittently between 2024z and 2026z. This anomaly resulted in the loss of seven frames of SSR data. * On day 140 (May 20), during the DSS-35 support for Ahead, BOT was 2.8 hours late as a result of the antenna azimuth tape units failing when water entered the weatherproof shroud. The antenna was eventually declared operational once the leak was sealed and the heads dried. Telemetry was received in the MOC 3.25 hours late at 0530z and SSR pointers repositioned and all SSR data was recovered on the next support. See DR #C112701 for more information. * On day 140 (May 20), during the DSS-24 support for Ahead, turbo decoder lock was lost briefly at 141-0146z. This anomaly resulted in the loss of one frame of SSR data. * On day 138, the SECCHI instrument reset at 00:58:41z. The SECCHI team reconfigured the instrument to operational mode by 139-0300z. This was the 44th reset of SECCHI on the Ahead observatory. * The average daily science data return for Ahead was 5.9 Gbits during this week. * The next recovery attempts for Behind are June 9,10,11. The next meeting to discuss recovery operations is June 1. Week 21 (May 22-28) * The 99th momentum dump on Ahead was successfully carried out yesterday (May 22), with ignition at 14:00 UT, and imparted an estimated delta-V of 0.084 m/s. The maneuver lasted 170 seconds. * Ahead has 8 passes during the week, and overall coverage is nominal. There are seven passes at 720 kbps, and one at 240 kbps. * There are no passes for Behind during the week. * IMPACT is planning to increase their magnetometer telemetry rate. This may happen either today (May 23) or tomorrow (May 24) Week 22 (May 29-Jun 4) * Monday, May 29, is Memorial Day, which is a holiday at APL. * There will be an upgrade of the restricted IOnet on Thursday, June 1, between 11-19 UT. This will occur between tracks, and is expected to have no effect. * Ahead has 8 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, and one at 160 kbps. * There are no tracks for Behind during the week. Week 23 (Jun 5-11) * Monday, Jun 5, 14-20 UT, is a backup date for the IOnet upgrade scheduled for the previous Thursday. This will also be between tracks. * Ahead has 9 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, one at 240 kbps, and two at 160 kbps. * Recovery tracks for Behind are scheduled for Friday, Saturday, and Sunday, Jun 9-11. The first two tracks will use the 80 kW transmitter on station 26. The last track will use station 43, and will include the Radio Science Receiver. Week 24 (Jun 12-18) * STEREO Ahead reaches aphelion on Jun 13. * The 39th SECCHI stepped calibration roll is scheduled for Tuesday, Jun 13, starting at 09:15 UT. System momentum is expected to be 1 N-m-s. This will be the eighth calibration roll without gyros. * Battery discharge maintenance will be carried out on Ahead on Wednesday, Jun 14, for 2 hours starting at 15:00 UT during a track. The battery state of charge will be taken down to 86-88% for testing. This is not expected to affect science operations. * Ahead has 10 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, three at 240 kbps, and one at 160 kbps. * There are no tracks for Behind during the week. Week 25 (Jun 19-25) * Ahead has 10 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, and four at 240 kbps. * There are no tracks for Behind during the week. Week 26 (Jun 26-Jul 2) * DSN stations will be down for several hours on Jun 26 for a "Follow the Sun" exercise. STEREO Ahead has tracks scheduled before and after this event, and will not be affected. * The 100th momentum dump on Ahead is scheduled for Jun 29, starting at 17:30 UT. This will be the 19th dump without using the gyros. * Ahead has 13 tracks during the week, and overall coverage is nominal There are eight tracks at 720 kbps, three at 240 kbps, and two at 160 kbps. * There are no tracks for Behind during the week. Week 27 (Jul 3-9) * Tuesday, July 4, is Independence Day, which is a holiday at APL. * Ahead has 9 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, one at 240 kbps, and one at 160 kbps. * There are no tracks for Behind during the week. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 21: M May 22 (142) Ahead: Momentum dump, 14:00 UT T May 23 (143) W May 24 (144) T May 25 (145) F May 26 (146) S May 27 (147) S May 28 (148) ------------------------------------------------------------------------------- Scheduled activities for Week 22: M May 29 (149) Memorial Day T May 30 (150) W May 31 (151) T Jun 01 (152) F Jun 02 (153) S Jun 03 (154) S Jun 04 (155) ------------------------------------------------------------------------------- Scheduled activities for Week 23: M Jun 05 (156) T Jun 06 (157) W Jun 07 (158) T Jun 08 (159) F Jun 09 (160) Behind: Battery recovery track with station 26 S Jun 10 (161) Behind: Battery recovery track with station 26 S Jun 11 (162) Behind: Carrier recovery track with station 43 ------------------------------------------------------------------------------- Scheduled activities for Week 24: M Jun 12 (163) T Jun 13 (164) Ahead: Aphelion. SECCHI calibration roll, 09:15 UT W Jun 14 (165) Ahead: Battery discharge maintenance, 15:00 UT T Jun 15 (166) F Jun 16 (167) S Jun 17 (168) S Jun 18 (169) ------------------------------------------------------------------------------- Scheduled activities for Week 25: M Jun 19 (170) T Jun 20 (171) W Jun 21 (172) T Jun 22 (173) F Jun 23 (174) S Jun 24 (175) S Jun 25 (176) ------------------------------------------------------------------------------- Scheduled activities for Week 26: M Jun 26 (177) DSN stations down for "Follow the Sun" exercise T Jun 27 (178) W Jun 28 (179) T Jun 29 (180) Ahead: Momentum dump, 17:30 UT F Jun 30 (181) S Jul 01 (182) S Jul 02 (183) ------------------------------------------------------------------------------- Scheduled activities for Week 27: M Jul 03 (184) T Jul 04 (185) Independence Day W Jul 05 (186) T Jul 06 (187) F Jul 07 (188) S Jul 08 (189) S Jul 09 (190) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2017: 2018: * Mar 5 Ahead: Mercury transit 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