STEREO Weekly Meeting Minutes for 2018-01-23 (Week 4) 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. 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 3 (Jan 15-21) * On day 015 (Jan 15), during the DSS-34 support, turbo decoder lock was lost briefly at 0747z and 0912z. This anomaly resulted in the loss of 3 frames of real-time telemetry and SSR data. * On day 016 (Jan 16) during a 3 hour 4 kHz carrier recovery search pattern support with DSS-63, lost command bind as well as all telemetry binds on all command workstations for Ahead and Behind at 015-2037z due to a network issue between GSFC and APL. Command and telemetry binds were re-established at 016-1108z. 120 commands were transmitted during the support for carrier recovery. No carrier was detected by either the DSN station or the radio science receiver team. This anomaly resulted in the loss of 2 hours of commanding. Only 6 points on the pattern were covered. Three commands must be received sequentially to power on the transmitter. * On day 018 (Jan 18), the scheduled DSS-14 recovery support did not occur to allow for emergency maintenance on the station. * On day 020 (Jan 20), during a 4 hour 1 kHz carrier recovery support with DSS-63, antenna brakes were set at 1206z. The antenna was reset and the uplink resumed at 1213z. This anomaly resulted in the loss of one command segment. See DR#M110439 for more information. Overall, 420 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 21 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. * The average daily science data return for Ahead was 7.1 Gbits during this week. Week 4 (Jan 22-28) * The fourth SECCHI HI stray light calibration maneuver started Tuesday, Jan 23 at 17:00 UT. This maneuver involves off-pointing in the Y axis direction by a little over a degree. There are seven off-points in all. The sequence will run for about 1.75 hours. System momentum will be about 9 N-m-s. This will be the first time this calibration will be carried out without gyros. * The MOC simulated the wheel speeds during the off-point maneuver. Fine pointing along the Y axis should be stable during the period. * The 106th momentum dump is scheduled for Thursday, Jan 25, with ignition at 15:30 UT. This will be the 25th dump without gyros. This is a week or so early, due to scheduling constraints. * On Wednesday, Jan 24, Behind would resume 125 bps uplink on LGA assuming nominal operations (3-axis stabilized). * Ahead has 13 tracks during the week, and overall coverage in nominal. There are seven tracks at 720 kbps, two at 360 kbps, and four at 240 kbps. * Weekly recovery operations for Behind continue. A battery recovery search pattern track occurred on Tuesday, Jan 23, and the corresponding carrier recovery search pattern track will be on Thursday, Jan 25 on DSS-14. On Sunday, Jan 28, a battery recovery 1 kHz sweep sequence is scheduled on DSS-63. Week 5 (Jan 29-Feb 4) * Ahead has 14 tracks during the week, and overall coverage is nominal. There are eight tracks at 720 kbps, five at 240 kbps, and one at 160 kbps. * A carrier search pattern track for Behind is scheduled for Monday, Jan 29. The previous Behind track was actually a battery 1 kHz sweep sequence, but the track duration did not support a carrier search pattern. The 1 kHz sweep sequences will be used on Wednesday, Jan 31 (battery), and Friday, Feb 2 (carrier). A battery recovery search pattern will be carried out on Sunday, Feb 4. Week 6 (Feb 5-11) * Ahead has 16 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, one at 360 kbps, and eight at 240 kbps. * Nominal 4 kHz recovery tracks for Behind are scheduled for Monday, Feb 5, and Wednesday, Feb 7. A 1 kHz carrier recovery track is scheduled for Friday, Feb 9, and a battery recovery search pattern track is scheduled for Sunday, Feb 11. Week 7 (Feb 12-18) * Ahead has 15 tracks during the week, and overall coverage is nominal. There are eleven tracks at 720 kbps, two at 360 kbps, and two at 240 kbps. * A carrier recovery search pattern track for Behind is scheduled for Tuesday, Feb 13, and 1 kHz recovery tracks are scheduled for Friday, Feb 16 (battery), and Sunday, Feb 18 (carrier). * Station 43 comes back online. Week 8 (Feb 19-25) * APL is open on Presidents Day (Monday Jan 19) * The 42nd SECCHI stepped calibration roll is scheduled for Tuesday, Feb 20, starting at 12:30 UT and taking 4.5 hours. This will be the midpoint roll. System momentum will be 4 N-m-s. This will be the 11th stepped calibration roll without gyros. Procedure has been updated to assist with finer pointing. * Work will be performed on the JPL network for four hours starting at 22:45 UT on Monday, Feb 22. There are no STEREO tracks during this period. * Ahead has 14 tracks during the week, and overall coverage is nominal. There are eight tracks at 720 kbps, four at 360 kbps, and two at 240 kbps. * Recovery search pattern tracks for Behind are scheduled for Tuesday, Feb 20 (battery) and Wednesday, Feb 21 (carrier). 1 kHz frequency acquisition sequence recovery tracks are scheduled for Saturday, Feb 24 (battery) and Sunday, Feb 25 (carrier). Week 9 (Feb 26-Mar 4) * Ahead has 10 tracks during this week, and overall coverage is nominal. There are six tracks at 720 kbps, one at 360 kbps, and three at 240 kbps. * Recovery search pattern tracks for Behind are scheduled for Tuesday, Feb 27 (battery) and Friday, Mar 2 (carrier), and a 1 kHz frequency acquisition sequence recovery track is scheduled for Sunday, Mar 4 (battery). Week 10 (Mar 5-11) * Mercury transit for Ahead on Monday Mar 5, probably early in the day, but need to get an update on time * The 107th momentum dump is scheduled for Monday Mar 5 stating at 16:00 UT. This is the 26th the without the gyros. It will be rescheduled if it conflicts with the Mercury transit, but this is not expected. * Daylight savings time begins Sunday Mar 11 at 07:00 UT. * 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 120 kbps. * Recovery search pattern tracks for Behind are scheduled on Tuesday May 6 (carrier recovery 4 kHz sweep sequence), Thursday Mar 8 (battery), and Saturday Mar 10 (carrier). COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 04: M Jan 22 (022) T Jan 23 (023) Ahead: SECCHI HI stray light calibration offpoint, 17:00 UT Behind: Recovery track, DSN 63 (search pattern, battery) W Jan 24 (024) T Jan 25 (025) Ahead: Momentum dump, 15:30 UT Behind: Recovery track, DSN 14 (search pattern, carrier) F Jan 26 (026) S Jan 27 (027) S Jan 28 (028) Behind: Recovery track (1 kHz, battery) ------------------------------------------------------------------------------- Scheduled activities for Week 05: M Jan 29 (029) Behind: Recovery track, DSN 63 (search pattern, carrier) T Jan 30 (030) W Jan 31 (031) Behind: Recovery track, DSN 63 (1 kHz, battery) T Feb 01 (032) F Feb 02 (033) Behind: Recovery track, DSN 63 (1 kHz, carrier) S Feb 03 (034) S Feb 04 (035) Behind: Recovery track, DSN 63 (search pattern, battery) ------------------------------------------------------------------------------- Scheduled activities for Week 06: M Feb 05 (036) Behind: Recovery track, DSN 63 (4 kHz) T Feb 06 (037) W Feb 07 (038) Behind: Recovery track, DSN 14 (4 kHz) T Feb 08 (039) F Feb 09 (040) Behind: Recovery track, DSN 63 (1 kHz, carrier) S Feb 10 (041) S Feb 11 (042) Behind: Recovery track, DSN 14 (search pattern, battery) ------------------------------------------------------------------------------- Scheduled activities for Week 07: M Feb 12 (043) T Feb 13 (044) Behind: Recovery track, DSN 14 (search pattern, carrier) W Feb 14 (045) T Feb 15 (046) F Feb 16 (047) Behind: Recovery track, DSN 63 (1 kHz, battery) S Feb 17 (048) S Feb 18 (049) Behind: Recovery track, DSN 63 (1 kHz, carrier) ------------------------------------------------------------------------------- Scheduled activities for Week 08: M Feb 19 (050) T Feb 20 (051) Ahead: SECCHI calibration roll, 12:30 UT Behind: Recovery track, DSN 63 (search pattern, battery) W Feb 21 (052) Behind: Recovery track, DSN 43 (search pattern, carrier) T Feb 22 (053) F Feb 23 (054) S Feb 24 (055) Behind: Recovery track, DSN 63 (1 kHz, battery) S Feb 25 (056) Behind: Recovery track, DSN 63 (1 kHz, carrier) ------------------------------------------------------------------------------- Scheduled activities for Week 09: M Feb 26 (057) T Feb 27 (058) Behind: Recovery track, DSN 14 (search pattern, battery) W Feb 28 (059) T Mar 01 (060) F Mar 02 (061) Behind: Recovery track, DSN 14 (search pattern, carrier) S Mar 03 (062) S Mar 04 (063) Behind: Recovery track, DSN 14 (1 kHz, battery) ------------------------------------------------------------------------------- Scheduled activities for Week 10: M Mar 05 (064) Ahead: Mercury Transit Ahead: 107th momentum dump T Mar 06 (065) Behind: Recovery track (4 kHz, carrier) 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 (search pattern, carrier) S Mar 11 (070) ------------------------------------------------------------------------------- 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