STEREO Weekly Meeting Minutes for 2018-01-16 (Week 3) 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 2 (Jan 8-14) * On day 010 (Jan 10), during the DSS-34 support for Ahead, turbo decoder lock was lost briefly at 0913z. This anomaly resulted in the loss of 2 frames of SSR data. * On day 010 (Jan 10), during the DSS-15 support for Ahead, the transmitter tripped off-line at 011-0130z. The transmitter was recalibrated and the uplink was established at 0136z. This anomaly resulted in the loss of 6 minutes of commanding and two-way tracking data and 308 frames of real-time telemetry and SSR data. See DR# G118802 for more information. * On day 011 (Jan 11), during the DSS-55 support for Ahead, turbo decoder lock was lost briefly 1300z, 1327z, and 1328z. This anomaly resulted in the loss of 10 frames of real-time telemetry and SSR data. * On day 011 (Jan 11), during the DSS-63 support for Ahead, the antenna brakes were set at 1815z due to low film height. The antenna was reset and SSR pointers were repositioned to minimize data loss. This anomaly resulted in the loss of 4 minutes of real-time telemetry, commanding, and tracking data. All SSR data were received. See DR #M110428 for more information. * On day 014 (Jan 14), during the DSS-63 support for Ahead, telemetry lock was lost intermittently between 1418z through 1527z due to heavy rain at the Madrid complex. This anomaly resulted in the loss of 49,158 frames of real-time telemetry and SSR data. See DR# M110433 for more information. * On day 007 (Jan 7) fine pointing was lost beginning at 1004z through 008-0724z. These occurrences are associated with transients that occurred as wheel 2 passed through zero. In total, there were 44 occurrences of the Fine Specs Met flag being zero for 21 hours which is well within the 3-sigma jitter specification. These transients can occur with no gyro operations and are not indicative of any problem with the spacecraft G&C. * The average daily science data return for Ahead was 6.8 Gbits during this week. * On day 009 (Jan 9), during a 3.5 hour 1 kHz battery recovery support for Behind with DSS-63, the station stopped tracking due to antenna brakes being set at 1107z. After station personnel cleared the problem at 1235z, the uplink was resumed and 170 commands were transmitted for battery state of charge recovery. Due to the anomaly and duration of the support, only 18 of the 36 frequency segments were commanded. See DR# M110423 for more information. * On day 012 (Jan 12), during a 4 hour 1 kHz carrier recovery support for Behind with DSS-63, 440 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 22 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. * On day 014 (Jan 14), during a 3 hour 4 kHz battery recovery search pattern support with DSS-14, 320 commands were transmitted during the support. All 7 points on the pattern were covered twice. Week 3 (Jan 15-21) * The MOC lost telemetry bind yesterday (Jan 15) for both Ahead and Behind. This affected the Behind support this morning, resulting in late commanding. * The previously scheduled Behind support for Thursday, Jan 18, has been deleted due to an emergency at the station. * Ahead has 16 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, one at 360 kbps, eight at 240 kbps, and one at 160 kbps. * A carrier recovery search pattern track for Behind is scheduled for Tuesday, Jan 16. A carrier recovery track using the 1 kHz frequency acquisition sequence is scheduled for Saturday, Jan 20 (carrier). Week 4 (Jan 22-28) * The fourth SECCHI HI stray light calibration maneuver is scheduled for Tuesday, Jan 23, starting 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 is scheduled for Tuesday, Jan 23, and the corresponding carrier recovery search pattern track will be on Friday, Jan 26. On Sunday, Jan 28, a battery recovery 1 kHz sweep sequence is scheduled. 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 seach 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) * The 42nd SECCHI stepped calibration roll is scheduled for Tuesday, Feb 20, starting at 12:30 UT. This will be the midpoint roll. System momentum will be 4 N-m-s. This will be the 11th stepped calibration roll without gyros. * 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 frequncy 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, Other * It was pointed out that a transit of Mercury as seen from STEREO Ahead is predicted to occur on Mar 5. The MOC is refining thei calculations of this event. * The MOC is updating the procedure for the SECCHI stepped calibration roll to reduce the chance of excessive jitter. They are looking into how much this will increase the duration of the maneuver, and will look at the simulator to see how this will affect the pointing. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 03: M Jan 15 (015) Martin Luther King Day T Jan 16 (016) Behind: Recovery track, DSN 63 (search pattern, carrier) W Jan 17 (017) T Jan 18 (018) F Jan 19 (019) S Jan 20 (020) Behind: Recovery track, DSN 63 (1 kHz, carrier) S Jan 21 (021) ------------------------------------------------------------------------------- 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) ------------------------------------------------------------------------------- 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