STEREO Weekly Meeting Minutes for 2017-10-17 (Week 42) ANNOUNCEMENTS ------------- * Power substation maintenance at the STEREO MOC is currently scheduled for Saturday, Oct 21, between 10-22 UT. Portable generators are being brought in, so that mission operations should not be affected. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * Attempts to recover Behind have transitioned from a weekly schedule to a daily schedule. Two days each week use the older 1 kHz frequency acquisition sequence, in case the nominal frequency has shifted, with one day devoted to battery recovery, and one day devoted to carrier recovery. This typically is scheduled for Monday and Tuesday. The remainder of the week uses the faster 4 kHz frequency acquisition sequence. Two of those days use a search pattern consisting of two diamonds, based on the estimated uncertainty in the ephemeris. The double diamond pattern is executed twice, once to send commands, and then again 40 minutes later to listen for the carrier. This search pattern will be run twice a week, once for battery recovery, and once for carrier recovery. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 41 (Oct 9-15) * On day 282 (Oct 9), during the DSS-63 support for Ahead, turbo decoder lock was lost intermittently beginning at 0950z through 1103z. At 1002z, SSR pointers were repositioned to minimize data loss. After the station switched antenna tracking modes 1102z, the issued cleared. At 1216z, the primary command workstation rebooted after transitioning to the backup generator from a loss of commercial power. The progress of the 103rd momentum dump was monitored on the backup command workstation. These anomalies resulted in the loss of 5103 frames of real-time telemetry and SSR data. See DR #M110265 for more information. * On day 283 (Oct 10), during the ESA Malargue (DSS-84) support for Ahead, initial telemetry reception was delayed 3 minutes due to a data control configuration at the DSN. Telemetry was received at 2058z. At 2232z, the primary command workstation rebooted after transitioning to the backup generator from a loss of commercial power. The track was monitored on the backup command workstation for 10 minutes. Post track, the issue with the primary command workstation rebooting upon loss of commercial power was traced to the workstation being on a non-UPS circuit after recent maintenance was performed. Post track, it was determined that the science SSR playback was started 13 minutes before BOT. As this missing data was retrieved on day 287, a new version 05, of the data products has been created. All SSR data were recovered. These anomalies resulted in the loss of 3 minutes of real-time telemetry and monitor data. See DR# N110802 for more information. * On day 284 (Oct 11), during the DSS-35 support for Ahead, monitor data was lost for 32 minutes beginning at 0710z due to both monitor data servers going off-line at the DSN. Monitor data was restored at 0742z. This anomaly resulted in the loss of 32 minutes of monitor data. All SSR data was recovered. See DR# N110802 for more information. * On day 284 (Oct 11), during the DSS-14 support for Ahead, turbo decoder lock was lost intermittently beginning at 1849z. At 1945z, SSR pointers were repositioned to minimize data loss. Later at 2043z, SLE command and telemetry binds were lost. The binds were restored at 2141z. All SSR data were recovered. These anomalies resulted in the loss of 58 minutes of real-time telemetry and monitor data. See DR #G118549 for more information. * On day 282 (Oct 9), the 103rd momentum dump on Ahead was executed successfully at 1200z, which imparted an estimated delta V of 0.089 m/sec. This was the 22nd momentum dump that did not use the IMU. After thruster operations complete, there was a 0.73 degree of roll angle error which was dampened out over the next 15.5 minutes. Fine pointing stabilized 2.4 minutes after completion of the momentum dump. * The average daily science data return for Ahead was 5.7 Gbits during this week. * Daily attempts to recover Behind continued. No downlink signal was detected during the week. * On day 282 (Oct 9), during a 2.5 hour 1 kHz battery recovery support for Behind with DSS-14, 189 commands were transmitted for battery state of charge recovery. Due to the duration of the support, only 21 of the 36 frequency segments were commanded. * On day 283 (Oct 10), during a 3.5 hour 1 kHz carrier recovery support for Behind with DSS-14, the transmitter tripped off-line at 1403z. It was placed back on line at 1409z and one command segment was lost. See DR #G118542 for more information. 360 commands were sent for transmitter carrier recovery. No carrier was detected by either the DSN station or the radio science receiver team. Due to the duration of the support and the increased commands for each step, only 18 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. * On day 284 (Oct 11), during a 4 hour 4 kHz carrier recovery support for Behind with DSS-14, 420 commands were transmitted during the support. At 1455z, moved the antenna to -0.02 degrees along track for uplink optimization and continued uplinking. No carrier was detected by either the DSN station or the radio science receiver team after attempting to power on the TWTA for 30 minutes. Transitioned to battery recovery operations for the remainder of the support which consists of repeatedly sweeping a 4 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. * On day 285 (Oct 12), during a 3 hour 4 kHz battery recovery search pattern support for Behind with DSS-63, 320 commands were transmitted during the support for battery state of charge recovery. All 7 points on the pattern were covered twice. * On day 286 (Oct 13), during a 3.1 hour 4 kHz carrier recovery search pattern support for Behind with DSS-14, 320 commands were transmitted during the support for carrier recovery. No carrier was detected by either the DSN station or the radio science receiver team. Three commands must be received sequentially to power on the transmitter. * On day 287 (Oct 14), during a 4 hour 4 kHz carrier recovery support for Behind with DSS-14, 420 commands were transmitted during the support. No carrier was detected by either the DSN station or the radio science receiver team after attempting to power on the TWTA for 30 minutes. Transitioned to battery recovery operations for the remainder of the support which consists of repeatedly sweeping a 4 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. * On day 288 (Oct 15), during a 3.5 hour 4 kHz carrier recovery support for Behind with DSS-14, 380 commands were transmitted during the support. No carrier was detected by either the DSN station or the radio science receiver team after attempting to power on the TWTA for 30 minutes. Transitioned to battery recovery operations for the remainder of the support which consists of repeatedly sweeping a 4 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. Week 42 (Oct 16-22) * The station 14 transmitter was offline during the Behind support yesterday (Oct 16), resulting in the loss of the battery recovery double diamond search pattern. * Power substation maintenance is currently scheduled for Saturday, Oct 21. See above for details. * ESA stations will be used four times during the week, including both New Norcia and Malargue stations. * Ahead has 16 tracks during the week, and overall coverage is nominal. There are three tracks at 720 kbps, two at 240 kbps, and eleven at 160 kbps. * Recovery tracks for Behind are scheduled every day using the 70-m antenna, of 2.5-3.7 hour durations with the 1 kHz frequency segmented acquisition sequence being used on Thursday for battery recovery and Friday for carrier recovery. Double diamond shaped search patterns will be used on Monday (battery) and Wednesday (carrier). Week 43 (Oct 23-29) * 11th launch anniversary of the STEREO mission on Oct. 25th. * Ahead has 19 tracks during the week, and overall coverage is nominal. There are three tracks at 720 kbps, three at 240 kbps, and thirteen at 160 kbps (two tracks are using ESA stations). * Recovery tracks for Behind are scheduled every day using the 70-m stations, of 2.5-4 hour durations with the 1 kHz frequency segmented acquisition sequence being used on Tuesday for battery recovery and Wednesday for carrier recovery. Double diamond shaped search patterns will be used on Monday (battery) and Thursday (carrier). Week 44 (Oct 30-Nov 5) * Daily standard time in the US ends on Sunday, Nov 5. * Ahead has 16 tracks during the week, and overall coverage is nominal. There are two tracks at 720 kbps, three at 240 kbps, and eleven at 160 kbps. * This is the last week of daily attempts to contact Behind. Recovery tracks are scheduled every day using 70 m stations, of 2-3.2 hour durations. DSN time starting this week is very contentious due to the line-up of multiple missions in the same region of the sky, and the fact that only two 70 meter DSN dishes are operating. Double iamond shaped search patterns will be used on Monday (battery) and Friday (carrier). The 1 kHz frequence segmented acquisition sequence will not be used during the week because of the short track durations. Week 45 (Nov 6-12) * Ahead has 18 tracks during the week, and overall coverage is nominal. There are two tracks at 720 kbps, three at 240 kbps, and thirteen at 160 kbps. Four of these tracks use ESA stations. * Tracks to recover Behind switch to a weekly schedule, with tracks scheduled to keep within the 3 day onboard timer. Behind recovery tracks are scheduled for Tuesday, Friday, and Saturday. The Tuesday and Friday passes will use the double diamond search pattern, with the first for battery recovery, and the second for carrier recovery. Week 46 (Nov 13-19) * A 2.2 hour demonstration track with station 25 is scheduled for Monday, Nov 13. There will be no instrument commanding or SSR playback during this track. * The 104th momentum dump on Ahead is scheduled for Wednesday, Nov 15, with ignition at 16:00 UT. This will be the 23rd dump without using the gyros. * Ahead has 16 tracks during the week, and overall coverage is nominal. There is one track at 720 kbps, three at 240 kbps, and twelve at 160 kbps. Two of those tracks use ESA stations. * Double diamond search patterns for Behind recovery are scheduled for Thursday, Nov 16 (battery) and Saturday, Nov 19. Another recovery track is scheduled for Monday, Nov 13. Week 47 (Nov 20-26) * Thursday, Nov 23, is Thanksgiving. Both Thursday and Friday, Nov 23-24, are holidays at APL. * Ahead has 16 tracks during the week, and overall coverage is nominal There is one track at 720 kbps, three at 240 kbps, and twelve at 160 kbps. * Double diamond search patterns for Behind recovery are scheduled for Tuesday, Nov 21 (battery) and Wednesday, Nov 22 (carrier). Another recovery track is scheduled for Saturday, Nov 25. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 42: M Oct 16 (289) T Oct 17 (290) W Oct 18 (291) T Oct 19 (292) F Oct 20 (293) S Oct 21 (294) S Oct 22 (295) Notes: * Behind recovery attempts each day. The Thursday and Friday Behind recovery passes use the original frequency acquisition sequence with the broader 18 kHz range. The first pass is for battery recovery, and the second is for carrier recovery. Double diamond shaped search patterns on Monday (battery) and Wednesday (carrier). ------------------------------------------------------------------------------- Scheduled activities for Week 43: M Oct 23 (296) T Oct 24 (297) W Oct 25 (298) 11th anniversary of STEREO launch T Oct 26 (299) F Oct 27 (300) S Oct 28 (301) S Oct 29 (302) Notes: * Behind recovery attempts each day. The Tuesday and Wednesday Behind recovery passes use the original frequency acquisition sequence with the broader 18 kHz range. The first pass is for battery recovery, and the second is for carrier recovery. Double diamond shaped search patterns on Monday (battery) and Thursday (carrier). ------------------------------------------------------------------------------- Scheduled activities for Week 44: M Oct 30 (303) T Oct 31 (304) W Nov 01 (305) T Nov 02 (306) F Nov 03 (307) S Nov 04 (308) S Nov 05 (309) Daylight savings time ends in US Notes: * Behind recovery attempts each day. Double diamond shaped search patterns on Monday (battery) and Friday (carrier). ------------------------------------------------------------------------------- Scheduled activities for Week 45: M Nov 06 (310) T Nov 07 (311) Behind: Recovery track, DSN 14 (search pattern, battery) W Nov 08 (312) T Nov 09 (313) F Nov 10 (314) Behind: Recovery track, DSN 14 (search pattern, carrier) S Nov 11 (315) Behind: Recovery track, DSN 14 S Nov 12 (316) Notes: * Behind recovery attempts switch back to weekly, roughly every 2-3 days. ------------------------------------------------------------------------------- Scheduled activities for Week 46: M Nov 13 (317) Ahead: Demonstration track with station 25 Behind: Recovery track, DSN 63 T Nov 14 (318) W Nov 15 (319) Ahead: Momentum dump, 16:00 UT T Nov 16 (320) Behind: Recovery track, DSN 63 (search pattern, battery) F Nov 17 (321) S Nov 18 (322) Behind: Recovery track, DSN 63 (search pattern, carrier) S Nov 19 (323) ------------------------------------------------------------------------------- Scheduled activities for Week 47: M Nov 20 (324) T Nov 21 (325) Behind: Recovery track, DSN 63 (search pattern, battery) W Nov 22 (326) Behind: Recovery track, DSN 14 (search pattern, carrier) T Nov 23 (327) Thanksgiving F Nov 24 (328) S Nov 25 (329) Behind: Recovery track, DSN 14 S Nov 26 (330) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 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