STEREO Weekly Meeting Minutes for 2017-10-31 (Week 44) ANNOUNCEMENTS ------------- * None INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * This is the last week using a daily schedule to attempt to recover Behind. 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 is run twice a week, once for battery recovery, and once for carrier recovery. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 43 (Oct 23-29) * On day 296 (Oct 23), during the DSS-35 support for Ahead, the transmitter tripped off-line at 0925z, 10 minutes before EOT. All SSR data were received. See DR# C112987 for more information. * On day 297 (Oct 24), during the DSS-35 support for Ahead, telemetry binds dropped at 0621z. Telemetry binds were re-established at 0814z. This anomaly resulted in the loss of 2 hours of real-time telemetry and monitor data. All SSR data were received. * On day 297 (Oct 24), during the DSS-55 support for Ahead, command and telemetry binds dropped again at 1642z. Telemetry binds were re-established at 1708z. This anomaly resulted in the loss of 26 minutes of real-time telemetry and monitor data. All SSR data were received. * On day 298 (Oct 25), before the DSS-55 support for Ahead began, telemetry binds dropped again at 1008z and 1237z. The NASCOM RIONet links between GSFC and APL were switched to the primary circuit at 1232z. Telemetry and command binds were reestablished at the nominal times for the track. All SSR data were received. * On day 299 (Oct 26), during the DSS-35 support for Ahead, turbo decoder lock was lost intermittently at 0454z through 0550z due to heavy rain at the Canberra complex. This anomaly resulted in the loss of 24,090 frames of real-time telemetry and SSR data, which is equivalent to about 15 minutes. See DR #C112997 for more information. * On day 300 (Oct 27), during the DSS-35 support for Ahead, acquisition of signal was 17 minutes late due to network issue at the Canberra complex. This anomaly resulted in the loss of 183 frames of real-time telemetry and SSR data during the subsequent transition for one-way to two-way communications. See DR #C113000 for more information. * On day 300 (Oct 27), during the DSS-25 support for Ahead, turbo decoder lock was lost intermittently beginning at 2222z through 2254z. This anomaly resulted in the loss of 94 frames of real-time telemetry and SSR data. * There was some discussion about the frequent droppings of bind, and whether it might be due to possible maintenance of the IONet and RIONet networks. Other missions besides STEREO, including SOHO and MMS, have been reporting problems. * On day 296 (Oct 23), the SECCHI instrument reset at 19:32:07z. The SECCHI team reconfigured the instrument to operational mode by 298-0000z. This was the 46th reset of SECCHI on the Ahead observatory. Part of the SECCHI recovery included a manual reset that is not counted as an anomaly. * The average daily science data return for Ahead was 4.5 Gbits during this week. * Daily passes to recover Behind continued during the week. No signal was seen from the Behind spacecraft. * On day 296 (Oct 23), during a 3.1 hour 4 kHz battery recovery search pattern support for Behind with DSS-14, commanding from the MOC was delayed by 22 minutes due to a configuration issue at the station. The issue was resolved at 1324z and 279 commands were transmitted during the support. Due to this anomaly, 2 of 7 points on the pattern were not covered twice. * On day 297 (Oct 24), during a 2.5 hour 1 kHz battery recovery support for Behind with DSS-63, 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 298 (Oct 25), the scheduled 3.5 hour 1 kHz carrier recovery support for Behind with DSS-14 did not occur as the transmitter was declared red on day 297. * On day 299 (Oct 26), the scheduled 3 hour 4 kHz carrier recovery search pattern support for Behind with DSS-14 did not occur as the transmitter was declared red on day 297. * On day 300 (Oct 27), during a 4 hour 4 kHz carrier recovery support for Behind with DSS-14, the command uplink was delayed 21 minutes due to network issue at the Goldstone complex. Later in the support, command bind was lost at 1702z and re-established at 1714z due to a network issue at JPL. This is a different issue than the loss of command and telemetry bind that was affected Ahead earlier in the week. See DR# G118593 for more information. 340 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 301 (Oct 28), during a 3 hour 4 kHz carrier recovery support for Behind with DSS-14, 320 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 302 (Oct 29), during a 3 hour 4 kHz carrier recovery support for Behind with DSS-14, 320 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 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 diamond 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 to test a new version of the tracking, telemetry, and commanding software. There will be no instrument commanding or SSR playback during this track. The downlink rate will be 160 kbps. After this demo, STEREO will continue to use the new software. * 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 17 tracks during the week, and overall coverage is nominal There are seven tracks at 240 kbps, and ten 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. Week 48 (Nov 27-Dec 3) * Ahead reaches perihelion on Dec 3. * Ahead has 15 tracks during the week, and overall coverage is short by about 8 hours of 70 meter time between Tuesday and Sunday. There is one track at 720 kbps, five at 240 kbps, and nine at 160 kbps. With the current schedule, the in situ intrument partitions are expected to overwrite for several hours several days in a row, in particular the partition for PLASTIC. The MOC is looking into possible options to increase the coverage. One of the 70 meter tracks for Behind has been reallocated to Ahead, and two ESA passes have been added to the schedule. * Double diamond search patterns for Behind recovery are scheduled for Tuesday, Nov 28 (battery) and Friday, Dec 1 (carrier). Week 49 (Dec 4-10) * The 41st SECCHI stepped calibration roll is scheduled for Tuesday, Dec 5, starting at 08:55 UT. System momentum will be about 1 N-m-s. This will be the perihelion roll, and will be the 10th roll without gyros. * Ahead has 14 tracks during the week, and overall coverage is nominal. There are two tracks at 720 kbps, four at 240 kbps, and eight at 160 kbps. There is a possibility of data loss if the recorders are still full at the beginning of the week. * Double diamond search patterns for Behind are scheduled for Tuesday, Dec 5 (battery) and Wednesday, Dec 6 (carrier). An additional recovery track is scheduled for Saturday, Dec 9. Week 50 (Dec 11-17) * Ahead has 14 tracks during the week, and overall coverage is short 8 hours between Wednesday and Friday. The MOC is considering the possibility of moving the Friday 70 meter support for Behind to Ahead. There are six passes at 240 kbps, and eight at 160 kbps. The IMPACT and SWAVES partitions may be okay, but PLASTIC is likely to lose data. * The DSN schedule for Ahead is expected to expected to improve in January. * Recovery attempts for Behind are scheduled for Monday, Thursday, and Friday, Dec 11,14,15. The Monday pass will be a double diamond search pattern for carrier recovery. There will be no battery search pattern during the week. The Friday pass may be reallocated to Ahead. Other * The MOC noted the passing away of Ida Baker of the DSN. * As the estimated recovery window for Behind is running out, the MOC and NASA management will get together to plan how to move forward. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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) APL holiday S Nov 25 (329) Behind: Recovery track, DSN 14 S Nov 26 (330) ------------------------------------------------------------------------------- Scheduled activities for Week 48: M Nov 27 (331) T Nov 28 (332) Behind: Recovery track, DSN 63 (search pattern, battery) W Nov 29 (333) T Nov 30 (334) F Dec 01 (335) Behind: Recovery track, DSN 63 (search pattern, carrier) S Dec 02 (336) S Dec 03 (337) Ahead: Perihelion Notes: * Track coverage for Ahead is short during the week, and data gaps may occur. ------------------------------------------------------------------------------- Scheduled activities for Week 49: M Dec 04 (338) T Dec 05 (339) Ahead: SECCHI stepped calibration roll, 08:55 UT Behind: Recovery track, DSN 63 (search pattern, battery) W Dec 06 (340) Behind: Recovery track, DSN 63 (search pattern, carrier) T Dec 07 (341) F Dec 08 (342) S Dec 09 (343) Behind: Recovery track, DSN 63 S Dec 10 (344) Notes: * Data gaps may occur due to track coverage shortages in previous week. ------------------------------------------------------------------------------- Scheduled activities for Week 50: M Dec 11 (345) Behind: Recovery track, DSN 63 (search pattern, carrier) T Dec 12 (346) W Dec 13 (347) T Dec 14 (348) Behind: Recovery track, DSN 63 F Dec 15 (349) Behind: Recovery track, DSN 14 S Dec 16 (350) S Dec 17 (351) Notes: * Track coverage for Ahead is short during the week, and data gaps may occur. ------------------------------------------------------------------------------- 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