STEREO Weekly Meeting Minutes for 2018-05-22 (Week 21) 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 20 (May 14-20) * On day 138 (May 18), during the DSS-55 support for Ahead, turbo decoder lock was lost intermittently at 1017z through 1054z and again at 1524z through 1534z due to rain at the Madrid complex. This anomaly resulted in the loss of 8181 frames of real-time telemetry and SSR data, which is equivalent to about 5 minutes at the 240 kbsp rate. See DR# M110598 for more information. * On day 139 (May 19), during the DSS-55 support for Ahead, turbo decoder lock was lost intermittently at 1126z through 1220z. This anomaly resulted in the loss of 1132 frames of real-time telemetry and SSR data, which is equivalent to about 1 minute at the 240 kbps rate, spread out over about 10 minutes. See DR# M110599 for more information. * On day 140 (May 20), during the DSS-43 support for Ahead, turbo decoder lock was lost intermittently at 0450z through 0456z and again at 0603z and 0638z. This anomaly resulted in the loss of 14 frames of SSR data. See DR# M110583 for more information. * On day 140 (May 20), during the DSS-55 support for Ahead, turbo decoder lock was lost briefly at 0855z. This anomaly resulted in the loss of one frame of SSR data. * On day 135 (May 15), the 109th momentum dump was executed successfully at 2000z, which imparted an estimated delta V of 0.089 m/sec. This was the 28th momentum dump that did not use the IMU. After thruster operations completed, there was a 0.1 degree of roll angle error which was dampened out over the next 8.5 minutes. Fine pointing stabilized 2.5 minutes after completion of the momentum dump. * The average daily science data return for Ahead was 6.5 Gbits during this week. * On day 138 (May 18), during a 3.5 hour 1 kHz battery recovery support for Behind with DSS-14, 270 commands were transmitted for battery state of charge recovery. Due to the duration of the support, only 30 of the 36 frequency segments were commanded. * On day 139 (May 19), during a 4 hour 1 kHz carrier recovery support for Behind with DSS-14, 440 commands were sent for transmitter carrier recovery. No carrier was detected by the DSN station. Due to the duration of the support and the increased commands for each step, only 22 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. * On day 140 (May 20), during a 4 hour 1 kHz carrier recovery support for Behind with DSS-14, 440 commands were sent for transmitter carrier recovery. No carrier was detected by the DSN station. Due to the duration of the support and the increased commands for each step, only 22 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. * The frequency acquisition sequence goes through 18 frequencies twice. Therefore, all frequencies were tested above, but not all of them were tested twice. 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 eleven tracks during the week, and overall coverage is now nominal after a 70 meter pass was added on Monday. There are seven tracks at 720 kbps, and four at 240 kbps. * There are no recovery passes for Behind during the week. Week 27 (Jul 2-8) * Wednesday, Jul 4, is Independence Day, which is a holiday at APL. * Ahead has ten tracks during the week, and overall coverage is nominal. There are five tracks at 720 kbps, three at 360 kbps, and two at 240 kbsp. * There are no recovery passes for Behind during the week. Other * A question was raised as to whether the report for the latest momentum dump was issued. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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) ------------------------------------------------------------------------------- Scheduled activities for Week 27: M Jul 02 (183) T Jul 03 (184) W Jul 04 (185) Independence Day T Jul 05 (186) F Jul 06 (187) S Jul 07 (188) S Jul 08 (189) ------------------------------------------------------------------------------- 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