STEREO Weekly Meeting Minutes for 2017-09-05 (Week 36) ANNOUNCEMENTS ------------- * None INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * Attempts to recover Behind have transitioned from a weekly schedule to a daily schedule. Two days each week use the older 1 kHz frequency acquisition sequence, in case the nominal frequency has shifted, with one day devoted to battery recovery, and one day devoted to carrier recovery. This typically is scheduled for Monday and Tuesday. The remainder of the week uses the faster 4 kHz frequency acquisition sequence. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 35 (Aug 28-Sep 3) * On day 243 (Aug 31), during the DSS-14 support for Ahead, turbo decoder lock was lost briefly at 244-0150z. This anomaly resulted in the loss of four frames of SSR data. * On day 241 (Aug 29), the 40th SECCHI stepped calibration was executed at 1155z for midpoint in the Ahead orbit. This was the 9th SECCHI stepped calibration roll to be conducted without gyro use. * The average daily science data return for Ahead was 5.7 Gbits during this week. * Recovery attempts were carried out daily during the week. No downlink signal has yet been detected. * The recovery readiness review was carried out last Tuesday, Aug 29, covering about 3 hours, and resulting in about a half dozen action items. Minutes will be distributed later today (Sep 5). * On day 240 (Aug 28), during a 3.6 hour support for Behind with DSS-14, 279 commands were transmitted for battery state of charge recovery. * On day 241 (Aug 29), during a 3.75 hours support for Behind with DSS-14, 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 19 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. * On day 242 (Aug 30), during a 4 hour support for Behind with DSS-14, 409 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. While it was planned to test the newly developed conical search pattern during this track, due to a configuration issue loading the search pattern, it was not tested. 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 243 (Aug 31), during a 3.1 hour support for Behind with DSS-14, 320 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 244 (Sep 1), during a 3.8 hour support for Behind with DSS-43, 380 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 245 (Sep 2), during a 4 hour support for Behind 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. * On day 246 (Sep 3), during a 4 hour support for Behind 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 36 (Sep 4-10) * The STEREO Ahead star tracker reset yesterday, Sep 4. Autonomy recovered the star tracker after 35 seconds. This resulted in fine pointing being lost for 85 seconds, with the spacecraft rolling by 0.4 degrees before recovering attitude control. The star tracker would have to be unavailable for 30 minutes before autonomy turns on the IMU. This was the 6th reset since launch, and the first since the cooler was set to a lower temperature set point back in December 2014. The last star tracker reset occured in September 2014, coincidently also on Labor Day, and was caused by a large flux of high energy particles. In that previous case, both STEREO spacecraft were affected, and it took several hours for the star trackers to promote back to operational mode. In the present case, there was an M-class flare directed towards Earth, but the space environment at the STEREO Ahead spacecraft was quiet. * The 102nd momentum dump on Ahead is scheduled for tomorrow, Sep 6, with ignition at 17:30 UT. This will be the 21st momentum dump without using the gyros. * A 1.5 hour project interface test with Ahead using station 34 will be carried out on Thursday, Sep 7. There will be no SSR downlink or instrument commanding during this pass. The downlink rate will be 160 kbps. * Ahead has 10 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, two at 240 kbps, and one at 160 kbps. * Recovery tracks for Behind are scheduled each day, of 2.5-4 hour durations. The older frequency acquisition sequence with the broader 18 kHz range will be used on Tuesday and Wednesday, with the first track being for battery recovery, and the second track being for carrier recovery. Week 37 (Sep 11-17) * Ahead has 11 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, three at 240 kbps, and one at 160 kbps. * Recovery tracks for Behind are scheduled every day, of 3-4 hour durations. The older frequency acquisition sequence with the broader 18 kHz range will be used on Thursday and Friday, with the first track being for battery recovery, and the second for carrier recovery. Week 38 (Sep 18-24) * Behind reaches perihelion on Sep 18. * A demonstration test with Ahead using station 25 is scheduled for Thursday, Sep 21. There will be no SSR playback or instrument commanding during this track. The downlink rate will be 160 kbps. This will be the transition track for Ahead with the new DSN software. * Ahead has 8 tracks during the week, all at 720 kbps, and overall coverage is nominal. * Recovery tracks for Behind are scheduled every day, of 3-4 hour durations. The older frequency acquisition sequence with the broader 18 kHz range will be used on Monday and Tuesday, with the first track being for battery recovery, and the second for carrier recovery. The Radio Science Receiver will be used with all tracks. Week 39 (Sep 25-Oct 1) * The current extended mission #3 officially ends on Sep 30. The Senior Review is ongoing. * Ahead has 10 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, one at 240 kbps, and two at 160 kbps. * Recovery tracks for Behind are scheduled every day, of 3-3.8 hour durations. the older frequency acquisition sequence with the broader 18 kHz range will be used on Monday and Tuesday, with the first track being for battery recovery, and the second for carrier recovery. The Radio Science Receiver will be used during all tracks. Week 40 (Oct 2-8) * Ahead has 11 tracks during the week, and overall coverage is nominal. There are five tracks at 720 kbps, three at 240 kbps, and three at 160 kbps. * Recovery tracks for Behind are scheduled every day, of 3-4 hour durations. The older frequency acquisition sequence with the broader 18 kHz range will be used on Monday and Tuesday, with the first track being for battery recovery, and the second for carrier recovery. Week 41 (Oct 9-15) * The 103rd momentum dump on Ahead is scheduled for Monday, Oct 9, starting at 12:00 UT. This will be the 22nd momentum dump without using the gyros. The dump is being scheduled early due to track coverage. * Due to entering a DSN high contention period, STEREO will start using the ESA 35 meter stations again. The ESA Malarque station will be used for 3 hours on Tuesday, Oct 10, with a telemetry rate of 160 kbps. Station 43 is going down for 5-6 months, and will be followed by station 63 for a similar period. * Ahead has 11 tracks during the week, and overall coverage is nominal. There are five tracks at 720 kbps, two at 240 kbps, and four at 160 kbps. * Recovery tracks for Behind are scheduled every day, of 3-4 hour durations. The older frequency acquisition sequence with the broader 18 kHz range will be used on Monday and Tuesday, with the first track being for battery recovery, and the second for carrier recovery. Week 42 (Oct 16-22) * ESA stations will be used three times during the week, including both New Norcia and Malargue stations. * Ahead has 15 tracks during the week, and overall coverage is nominal. There are three tracks at 720 kbps, two at 240 kbps, and ten at 160 kbps. * Recovery tracks for Behind are scheduled every day, of 2.5-3.7 hour durations. The older frequency acquisition sequence with the broader 18 kHz range will be used on Thursday and Friday, with the first track being for battery recovery, and the second for carrier recovery. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 36: M Sep 04 (247) Labor Day. Star tracker reset. T Sep 05 (248) W Sep 06 (249) Ahead: Momentum dump, 17:30 UT T Sep 07 (250) Ahead: Project interface test with station 34 F Sep 08 (251) S Sep 09 (252) S Sep 10 (253) Notes: * Behind recovery attempts each day. The Tuesday and Wednesday Behind recovery passes use the original frequency acquisition sequence with the broader 18 kHz range. The first pass is for battery recovery, and the second is for carrier recovery. ------------------------------------------------------------------------------- Scheduled activities for Week 37: M Sep 11 (254) T Sep 12 (255) W Sep 13 (256) T Sep 14 (257) F Sep 15 (258) S Sep 16 (259) S Sep 17 (260) Notes: * Behind recovery attempts each day. The Thursday and Friday Behind recovery passes use the original frequency acquisition sequence with the broader 18 kHz range. The first pass is for battery recovery, and the second is for carrier recovery. ------------------------------------------------------------------------------- Scheduled activities for Week 38: M Sep 18 (261) Behind: Perihelion T Sep 19 (262) W Sep 20 (263) T Sep 21 (264) Ahead: Demonstration test with station 25 F Sep 22 (265) S Sep 23 (266) S Sep 24 (267) Notes: * Behind recovery attempts each day. The Monday and Tuesday Behind recovery passes use the original frequency acquisition sequence with the broader 18 kHz range. The first pass is for battery recovery, and the second is for carrier recovery. ------------------------------------------------------------------------------- Scheduled activities for Week 39: M Sep 25 (268) T Sep 26 (269) W Sep 27 (270) T Sep 28 (271) F Sep 29 (272) S Sep 30 (273) S Oct 01 (274) Notes: * Behind recovery attempts each day. The Monday and Tuesday Behind recovery passes use the original frequency acquisition sequence with the broader 18 kHz range. The first pass is for battery recovery, and the second is for carrier recovery. ------------------------------------------------------------------------------- Scheduled activities for Week 40: M Oct 02 (275) T Oct 03 (276) W Oct 04 (277) T Oct 05 (278) F Oct 06 (279) S Oct 07 (280) S Oct 08 (281) Notes: * Behind recovery attempts each day. The Monday and Tuesday Behind recovery passes use the original frequency acquisition sequence with the broader 18 kHz range. The first pass is for battery recovery, and the second is for carrier recovery. ------------------------------------------------------------------------------- Scheduled activities for Week 41: M Oct 09 (282) Ahead: Momentum dump, 12:00 UT T Oct 10 (283) W Oct 11 (284) T Oct 12 (285) F Oct 13 (286) S Oct 14 (287) S Oct 15 (288) Notes: * Behind recovery attempts each day. The Monday and Tuesday Behind recovery passes use the original frequency acquisition sequence with the broader 18 kHz range. The first pass is for battery recovery, and the second is for carrier recovery. ------------------------------------------------------------------------------- Scheduled activities for Week 42: M Oct 16 (289) T Oct 17 (290) W Oct 18 (291) T Oct 19 (292) F Oct 20 (293) S Oct 21 (294) S Oct 22 (295) Notes: * Behind recovery attempts each day. The Thursday and Friday Behind recovery passes use the original frequency acquisition sequence with the broader 18 kHz range. The first pass is for battery recovery, and the second is for carrier recovery. ------------------------------------------------------------------------------- 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