STEREO Weekly Meeting Minutes for 2018-03-06 (Week 10) ANNOUNCEMENTS ------------- * Attempts to recover Behind will shift to back to a monthly schedule from the current weekly schedule. Weekly attempts will end in week 16, and the monthly attempts will pick up in week 20. 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. In some cases, the older "1 kHz" frequency acquisition sequence is used, with one day for battery recovery, and another for carrier recovery. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 9 (Feb 26-Mar 4) * On day 059 (Feb 28), during the DSS-43 support for Ahead, initial acquisition of telemetry was 1.7 hours late at 0156z due to an ongoing transmitter repair at the station. The SSR pointers were repositioned to minimize data loss. This anomaly resulted in the loss of 1.7 hours of real-time telemetry, commanding, and tracking data and 2 minutes of SECCHI data and 2.2 hours of spacecraft housekeeping data. See DRs #C113354 and for more information. * On day 059 (Feb 28), the spacecraft C&DH housekeeping partition (#4) on Ahead filled at 2134z for 3.2 hours due to the late acquisition of signal on day 059 with DSS-43. * On day 060 (Mar 1), the SECCHI SSR science partition (#19) on Ahead filled at 0008z for 34 minutes due to the late acquisition of signal on day 059 with DSS-43. * The average daily science data return for Ahead was 5.9 Gbits during this week. * On day 058 (Feb 27), during a 3.25 hour 4 kHz battery recovery search pattern support for Behind with DSS-14, 320 commands were transmitted during the support. All 7 points on the pattern were covered twice. * On day 061 (Mar 2) during a 3 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 063 (Mar 4), during a 3.25 hour 1 kHz battery recovery support for Behind with DSS-63, 252 commands were transmitted for battery state of charge recovery. Due to the duration of the support, only 28 of the 36 frequency segments were commanded. Week 10 (Mar 5-11) * The second Mercury transit for Ahead occured on Monday, Mar 5. The two DSN tracks on that day that were promoted to level 3 occurred successfully. * The 107th momentum dump was carried out on Monday, Mar 5. * Daylight savings time in the U.S. begins Sunday, Mar 11. * Ahead has 13 tracks during this week, and overall coverage is nominal. There are two tracks at 720 kbps, four at 360 kbps, and seven at 240 kbps. * A nominal 4 kHz recovery track for Behind is scheduled for Tuesday, May 6. Search pattern tracks are scheduled for Thursday, Mar 8 (battery), and Saturday Mar 10 (carrier). Week 11 (Mar 12-18) * Ahead has 15 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, two at 360 kbps, six at 240 kbps, and one at 160 kbps. * A battery recovery search pattern track for Behind is scheduled for Monday, Mar 12, and a nominal 4 kHz carrier recovery track is scheduled for Wednesday, Mar 14. 1 kHz frequency acquisition recovery tracks are scheduled for Friday, Mar 16 (battery), and Sunday, Mar 18 (carrier). Week 12 (Mar 19-25) * Ahead has 13 tracks during the week, and overall coverage is nominal. There are eight tracks at 720 kbps, and five at 240 kbps. * Search pattern recovery tracks for Behind are scheduled for Tuesday, Mar 20 (battery) and Wednesday, Mar 21 (carrier). A 1 kHz frequency acquisition sequence battery recovery track is scheduled for Saturday, Mar 24. Week 13 (Mar 26-Apr 1) * Passover begins Friday, March 30 and goes through April 7. Good Friday is March 30, and April 1 is Easter. * March 31 is aphelion for the Behind S/C. * Ahead has 16 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, four at 360 kbps, and six at 240 kbps. * A 1 kHz frequency acquisition sequence carrier recovery track is scheduled Monday, Mar 26. Search pattern recovery tracks are scheduled for Wednesday, Mar 28 (battery), and Saturday, Mar 31 (carrier). A 1 kHz frequency acquisition sequence battery recovery track is scheduled for Sunday, Apr 1. Week 14 (Apr 2-8) * Ahead has 18 passes during the week, and overall coverage is nominal. There are eight passes at 720 kbps, five at 360 kbps, and five at 240 kbps. * Carrier recovery search pattern tracks for Behind are scheduled for Monday, Apr 2, and Saturday, Apr 7. A 1 kHz frequency acquisition battery recovery track is scheduled for Wednesday, Apr 4. Week 15 (Apr 9-15) * The 108th momentum dump on Ahead is scheduled for Tuesday, Apr 10, with ignition at 15:00 UT. This will be the 27th dump without gyros. * Ahead has 15 passes during the week, and overall coverage is nominal. There are six tracks at 720 kbps, three at 360 kbps, and six at 240 kbps. * Search pattern recovery tracks for Behind are scheduled for Monday, Apr 9 (battery) and Wednesday, Apr 11 (carrier). 1 kHz frequency acquisition recovery tracks are scheduled for Friday, Apr 13 (battery) and Sunday, Apr 15 (carrier). COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 10: M Mar 05 (064) Ahead: Mercury transit, 02:25-05:27 UT Ahead: Momentum dump, 16:00 UT T Mar 06 (065) Behind: Recovery track, DSN 43 (4 kHz) W Mar 07 (066) T Mar 08 (067) Behind: Recovery track, DSN 43 (search pattern, battery) F Mar 09 (068) S Mar 10 (069) Behind: Recovery track, DSN 43 (search pattern, carrier) S Mar 11 (070) Daylight Savings Time begins in US ------------------------------------------------------------------------------- Scheduled activities for Week 11: M Mar 12 (071) Behind: Recovery track, DSN 14 (search pattern, battery) T Mar 13 (072) W Mar 14 (073) Behind: Recovery track, DSN 14 (4 kHz) T Mar 15 (074) F Mar 16 (075) Behind: Recovery track, DSN 43 (1 kHz, battery) S Mar 17 (076) S Mar 18 (077) Behind: Recovery track, DSN 14 (1 kHz, carrier) ------------------------------------------------------------------------------- Scheduled activities for Week 12: M Mar 19 (078) T Mar 20 (079) Behind: Recovery track, DSN 14 (search pattern, battery) W Mar 21 (080) Behind: Recovery track, DSN 14 (search pattern, carrier) T Mar 22 (081) F Mar 23 (082) S Mar 24 (083) Behind: Recovery track, DSN 43 (1 kHz, battery) S Mar 25 (084) ------------------------------------------------------------------------------- Scheduled activities for Week 13: M Mar 26 (085) Behind: Recovery track, DSN 43 (1 kHz, carrier) T Mar 27 (086) W Mar 28 (087) Behind: Recovery track, DSN 43 (search pattern, battery) T Mar 29 (088) F Mar 30 (089) S Mar 31 (090) Behind: Recovery track, DSN 14 (search pattern, carrier) S Apr 01 (091) Behind: Recovery track, DSN 14 (1 kHz, battery) ------------------------------------------------------------------------------- Scheduled activities for Week 14: M Apr 02 (092) Behind: Recovery track, DSN 14 (search pattern, carrier) T Apr 03 (093) W Apr 04 (094) Behind: Recovery track, DSN 43 (1 kHz, battery) T Apr 05 (095) F Apr 06 (096) S Apr 07 (097) Behind: Recovery track, DSN 14 (search pattern, carrier) S Apr 08 (098) ------------------------------------------------------------------------------- Scheduled activities for Week 15: M Apr 09 (099) Behind: Recovery track, DSN 14 (search pattern, battery) T Apr 10 (100) Ahead: Momentum dump, 15:00 UT W Apr 11 (101) Behind: Recovery track, DSN 14 (search pattern, carrier) T Apr 12 (102) F Apr 13 (103) Behind: Recovery track, DSN 43 (1 kHz, battery) S Apr 14 (104) S Apr 15 (105) Behind: Recovery track, DSN 43 (1 kHz, carrier) ------------------------------------------------------------------------------- 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