STEREO Weekly Meeting Minutes for 2018-01-02 (Week 1) 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 51 (Dec 18-24) * On day 353 (Dec 19), during the DSS-55 support for Ahead, the transmitter was declared red just prior to BOT due to a voltage regulator failure. After the voltage regulator was replaced, the transmitter was placed on-line at 1548z and SSR pointers were repositioned to prevent data loss from the uplink sweep. This anomaly resulted in the loss of 53 minutes of commanding and two-way tracking data. All SSR data were received. See DRs #M110396 for more information. * On day 355 (Dec 21), the 105th momentum dump on Ahead was executed successfully at 1600z, which imparted an estimated delta V of 0.093 m/sec. This was the 24th momentum dump that did not use the IMU. After thruster operations complete, there was a 0.93 degree of roll angle error which was dampened out over the next 15.8 minutes. Fine pointing stabilized 2.1 minutes after completion of the momentum dump. * The average daily science data return for Ahead was 6.0 Gbits during this week. * On day 357 (Dec 23) 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. Week 52 (Dec 25-31) * On day 360 (Dec 26), during the DSS-15 support for Ahead, the uplink was delayed 5 minutes due to a transmitter issue. The transmitter was recalibrated and the uplink was re-swept. This anomaly resulted in the loss of 5 minutes of commanding and two-way tracking data and 1.4 minutes of SSR and real-time data. See DR# G118769 for more information. * On day 365 (Dec 31), during the DSS-15 support for Ahead, the transmitter tripped off-line at 0034z. After the recalibrating, the transmitter was placed on-line at 0047z without re-sweeping. This anomaly resulted in the loss of 13 minutes of commanding and two-way tracking data and 543 frames of SSR and real-time data, which is equivalent to about 30 seconds at the 160 kbps rate. See DR# G118776 for more information. * On day 365 (Dec 31), during the DSS-63 support for Ahead, telemetry lock was lost intermittently between 1603z and 1606z due to rain at the Madrid complex. This anomaly resulted in the loss of 2892 frames of real-time and SSR data, which is equivalent to about 30 seconds at the 720 kbps rate. See DR# M110410 for more information. * The average daily science data return for Ahead was 6.3 Gbits during this week. * On day 359 (Dec 25), during a 3 hour 4 kHz battery recovery search pattern support for Behind with DSS-63, 320 commands were transmitted during the support. All 7 points on the pattern were covered twice. * On day 361 (Dec 27) during a 3 hour 4 kHz carrier recovery search pattern support for Behind with DSS-63, 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 363, during a 4 hour 4 kHz carrier recovery support with DSS-14, 420 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 1 (Jan 1-7) * Ahead has 15 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, two at 360 kbps, five at 240 kbps, and one at 160 kbps. * There are four recovery attempts for Behind during the week. A 1 kHz frequency acquisition pass for battery recovery was carried out Monday, Jan 1, along with the subsequent carrier recovery pass on Tuesday, Jan 2. Search pattern attempts will be carried out on Friday, Jan 5, for battery recovery, and Sunday, Jan 6, for carrier recovery. Week 2 (Jan 8-14) * Ahead has 14 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, one at 360 kbps, four at 240 kbps, and two at 160 kbps. * Recovery attempts for Behind using the 1 kHz frequency acquisition sequence are scheduled on Tuesday, Jan 9 (battery) and Friday, Jan 12 (carrier). A search pattern for battery recovery is scheduled for Sunday, Jan 14. Week 3 (Jan 15-21) * Jan 15 is the Martin Luther King Day holiday. Government offices will be closed, but APL will remain open. * 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. Recovery tracks using the 1 kHz frequency acquisition sequence are scheduled for Thursday, Jan 18 (battery), and Saturday, Jan 20 (carrier). * It was pointed out that all carrier recovery tracks for Behind have radio science receiver support. 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. 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 106th momentum dump is scheduled for Thursday, Jan 25, with ignition at 15:30 UT. This will be the 25th dump without gyros. * On Wednesday, Jan 24, Behind would resume 125 bps uplink on LGA assuming nominal operations. * 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. * The MOC has not received any word yet from NASA on any possible modifications for the recovery operations strategy. 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 is 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). COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 01: M Jan 01 (001) New Year Behind: Recovery track, DSN 14 (1 kHz, battery) T Jan 02 (002) Behind: Recovery track, DSN 63 (1 kHz, carrier) W Jan 03 (003) T Jan 04 (004) F Jan 05 (005) Behind: Recovery track, DSN 63 (search pattern, battery) S Jan 06 (006) S Jan 07 (007) Behind: Recovery track, DSN 14 (search pattern, carrier) ------------------------------------------------------------------------------- Scheduled activities for Week 02: M Jan 08 (008) T Jan 09 (009) Behind: Recovery track, DSN 63 (1 kHz, battery) W Jan 10 (010) T Jan 11 (011) F Jan 12 (012) Behind: Recovery track, DSN 63 (1 kHz, carrier) S Jan 13 (013) S Jan 14 (014) Behind: Recovery track, DSN 14 (search pattern, battery) ------------------------------------------------------------------------------- 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) Behind: Recovery track, DSN 14 (1 kHz, battery) 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) ------------------------------------------------------------------------------- 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