STEREO Weekly Meeting Minutes for 2017-08-29 (Week 35) 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 34 (Aug 21-27) * On day 237 (Aug 25), during the DSS-14 support for Ahead, turbo decoder lock was lost briefly at 0150zz. This anomaly resulted in the loss of 4 frames of real-time telemetry and SSR data. * On day 239 (Aug 27), during the DSS-34 support, turbo decoder lock was lost intermittently between 0131z and 0215z. This anomaly resulted in the loss of 8 frames of SSR data. * The average daily science data return for Ahead was 5.9 Gbits during this week. * Recovery attempts for Behind were carried out daily during the week. The original 1 kHz frequency acquisition sequence was used on Monday (battery recovery) and Tuesday (carrier recovery), with the remainder of the week using the 4 kHz sequence. Anywhere from 320-440 commands were sent each day. No downlink signal was detected. Details for the individual days are below. * A review was carried out this morning (Aug 29) of the procedures to be used for recovery. Minutes will be sent out later. * 70 meter recovery passes for Behind are planned daily until early November. * On day 233 (Aug 21), during a 2.5 hour support for Behind with DSS-14, command uplink was lost at 1335z for 40 minutes due to the station frequency segmented sweep sequence halting unexpectedly. This anomaly resulted in the loss of 5, out of 21, command segments. A total of 144 commands were transmitted for battery state of charge recovery. See DR #G118382 for more information. * On day 234 (Aug 22), during a 4 hours support for Behind with DSS-14, 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 235 (Aug 23), during a 3 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 236 (Aug 24), during a 3.25 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 237 (Aug 25), during a 3 hour support with DSS-43, 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 238 (Aug 26), during a 3 hour 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. * On day 239 (Aug 27), during a 4 hour support 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. Week 35 (Aug 28-Sep 3) * The 40th SECCHI stepped calibration roll on Ahead was carried out this morning (Aug 29). * On Wednesday, Aug 30, The DSN will be conducting a test of a conical search pattern of 0.04 degrees that may be used later in the year to search for the Behind spacecraft, if needed. The ephemeris error for Behind has grown, due to not much tracking coveage data after the momentum dump last year. * Ahead has 8 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, and two at 240 kbps. * Recovery tracks for Behind are scheduled each day, of 3.1-4 hour durations. The older frequency acquisition sequence with the finer 1 kHz steps will be used on Monday and Tuesday, with the first track being for battery recovery, and the second track being for carrier recovery. The Radio Science Receiver will be used for all tracks. Week 36 (Sep 4-10) * Monday, Sep 4, is Labor Day, which is an APL holiday. * The 102nd momentum dump on Ahead is scheduled for Wednesday, 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 finer 1 kHz steps 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 finer 1 kHz steps 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 finer 1 kHz steps 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 finer 1 kHz steps will be used on Monday and Tuesday, with the first track being for battery recovery, and the second for carrier recovery. 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 finer 1 kHz steps 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) * 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 finer 1 kHz steps will be used on Monday and Tuesday, with the first track being for battery recovery, and the second for carrier recovery. Other * The STEREO Science Center expressed thanks to APL for the space weather beacon support during the solar eclipse on Aug 21. It has been reported that some of the SECCHI beacon imagery was shown during the NASA live coverage of the eclipse. Also, some of the processed high resolution images were shown during a news conference on Aug 23. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 35: M Aug 28 (240) T Aug 29 (241) Ahead: SECCHI stepped calibration roll, 11:55 UT Behind: Recovery readiness review W Aug 30 (242) Behind: Test of conical search pattern T Aug 31 (243) F Sep 01 (244) S Sep 02 (245) S Sep 03 (246) Notes: * Behind recovery attempts each day. The first two Behind recovery passes use the original frequency acquisition sequence with the finer 1 kHz resolution. The first pass is for battery recovery, and the second is for carrier recovery. ------------------------------------------------------------------------------- Scheduled activities for Week 36: M Sep 04 (247) Labor Day 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 finer 1 kHz resolution. 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 finer 1 kHz resolution. 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 finer 1 kHz resolution. 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 finer 1 kHz resolution. 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 finer 1 kHz resolution. The first pass is for battery recovery, and the second is for carrier recovery. ------------------------------------------------------------------------------- Scheduled activities for Week 41: M Oct 09 (282) 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 finer 1 kHz resolution. 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