STEREO Weekly Meeting Minutes for 2017-11-07 (Week 45) ANNOUNCEMENTS ------------- * None INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * Behind has transitioned to a weekly schedule to attempt to recover the spacecraft. Passes are scheduled approximately every three days to keep within the 72 hour command loss timer. Typically, 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. An additional pass uses the standard configuration. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 44 (Oct 30-Nov 5) * On day 307 (Nov 3), during the DSS-14 support for Ahead, acquisition of signal was 21 minutes late due to loss of power at the Goldstone complex. SSR pointers were repositioned to minimize data loss. This anomaly resulted in the loss of 21 minutes of real-time telemetry, commanding, and tracking data. All SSR data were received. See DR #G118610 for more information. This was the only 70 meter track during the week. The loss of pass time resulted in problems with the PLASTIC data partition in the following week. See below for details. * On day 308 (Nov 4), during the DSS-55 support for Ahead, turbo decoder lock was lost briefly at 1036z and again at 1044z. This anomaly resulted in the loss of 2 frames of SSR data. * The average daily science data return for Ahead was 4.5 Gbits during this week. * This was the last week for daily recovery attempts for Behind. No signal was detected from the Behind spacecraft during the week. * On day 303 (Oct 30), during a 3.2 hour 4 kHz battery recovery search pattern support for Behind with DSS-14, 340 commands were transmitted during the support. All 7 points on the pattern were covered twice. * On day 304 (Oct 31), during a 2 hour 4 kHz carrier recovery support for Behind with DSS-14, 200 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 305 (Nov 1), during a 2 hour 4 kHz carrier recovery support for Behind with DSS-63, 200 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 306 (Nov 2), during a 2 hour 4 kHz carrier recovery support for Behind with DSS-63, 200 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 307 (Nov 3) during a 3.2 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. All 7 points on the pattern were covered twice. Three commands must be received sequentially to power on the transmitter. * On day 308 (Nov 4), during a 2 hour 4 kHz carrier recovery support for Behind with DSS-14, 200 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 309 (Nov 5), during a 2 hour 4 kHz carrier recovery support with DSS-14, 200 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 45 (Nov 6-12) * Yesterday, Nov 6, the PLASTIC partition on Ahead reached 95% full for 5.8 hours starting at 9:12 UT, and then again at 22:56 UT for 0.3 hours. This was due to the partial loss of a 70 meter track late in the previous week. * 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 six tracks at 360 kbps, one track at 240 kbps, and ten at 160 kbps. The data margins have been reanalyzed, and it was determined that two of the newer stations, DSN-35 and DSN-36 at Canberra, can have their nominal rates increased to 240 kbps, with a boost to 360 kbps when the entire pass is at high elevation. * 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 currently calculated to be short by about 8 hours of 70 meter time between Sunday and the following Tuesday. However, several tracks have been bumped up to 360 kbps, and the amount of data loss may diminish. There is one track at 720 kbps, three at 360 kpbs, three at 240 kbps, and eight 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 15 tracks during the week, and overall coverage is nominal. There are three tracks at 720 kbps, three at 360 kbps, one 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. A 70 meter pass on Wednesday has been moved to Ahead. * A double diamond carrier search pattern for Behind is scheduled for Tuesday, Dec 5. An additional recovery track is scheduled for Saturday, Dec 9. Week 50 (Dec 11-17) * Ahead has 17 tracks during the week, and overall coverage is now nominal. Two 70 meter passes for Behind have been reallocated to Ahead. There are three passes at 720 kbps, five at 360 kbps, one at 240 kbps, and eight at 160 kpbs. * The DSN schedule for Ahead is expected to expected to improve in January. * A single recovery attempts for Behind is scheduled for Thursday, Dec 14. The Week 51 (Dec 18-24) * The 105th momentum dump on Ahead is scheduled for Thursday, Dec 21st, with ignition at 16:00 UT. This will be the 24th dump without using the gyros. * Ahead 14 tracks during the week, and overall coverage is short about 4 houts between days 353-356 (Tuesday-Friday). There are three passes at 720 kbps, one at 360 kbps, and ten at 160 kbps. One 70 meter pass for Behind was reallocated to Ahead. * Behind recovery attempts are scheduled for Monday, Dec 18, and Saturday, Dec 23. The Saturday attempt will be a double diamond search pattern for carrier recovery. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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, carrier) W Dec 06 (340) 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) T Dec 12 (346) W Dec 13 (347) T Dec 14 (348) Behind: Recovery track, DSN 63 F Dec 15 (349) S Dec 16 (350) S Dec 17 (351) ------------------------------------------------------------------------------- Scheduled activities for Week 51: M Dec 18 (352) Behind: Recovery track, DSN 63 T Dec 19 (353) W Dec 20 (354) T Dec 21 (355) Ahead: Momentum dump, 16:00 UT F Dec 22 (356) S Dec 23 (357) Behind: Recovery track, DSN 14 (search pattern, carrier) S Dec 24 (358) 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