STEREO Weekly Meeting Minutes for 2017-08-22 (Week 34) ANNOUNCEMENTS ------------- * The Behind recovery readiness review has been rescheduled for Tuesday, August 29, 9 AM at APL, Bldg 200. A webex announcement has been sent out. If planning to come to APL for the review, please inform Dan Ossing. 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 33 (Aug 14-20) * On day 227 (Aug 15), during the DSS-34 support for Ahead, turbo decoder lock was lost briefly at 0505z and 0532z. This anomaly resulted in the loss of 4 frames of real-time telemetry and SSR data. * On day 227 (Aug 15), during the DSS-14 support for Ahead, BOT was 31 minutes late as a result of a waveguide interlock issue at the antenna. Once the interlock was cleared, telemetry was received in the MOC at 1841z and SSR pointers repositioned. All SSR data were recovered. See DR #G118359 for more information. * On day 228 (Aug 160, during the DSS-14 support for Ahead, BOT was 52 minutes late as a result of a waveguide coolant leak at the antenna. Once the leak was repaired, telemetry was received in the MOC at 1842z and SSR pointers repositioned. Later, turbo decoder lock was lost intermittently at 1914z through 1917z. These anomalies resulted in the loss of 17 frames of real-time telemetry data only. All SSR data were recovered. See DR #G118362 for more information. * On day 230 (Aug 18), a Return-To-Service (RTS) engineering demo was conducted with DSS-24 using Ahead. The purpose was to validate X-band tracking performance after the completion of the Membrane Dichroic testing. No uplink monitor data was received by the MOC for the duration of the support. See DR #G118366 for more information. The MOC sent four commands successfully. As the tracking, telemetry, and command data from this support were non-committed, the SSR was not played back and no instrument commands were sent. * The average daily science data return for Ahead was 5.7 Gbits during this week. * On day 226 (Aug 14), during a 3.2 hour support for Behind with DSS-14, command uplink was delayed 33 minutes to recalibrate the transmitter. This anomaly resulted in the loss of 3 command segments. A total of 259 commands were transmitted during the support. See DR #G118356 for more information. 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 228 (Aug 16), during a 3.7 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 230 (Aug 180, during a 3.75 hour support 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. Week 34 (Aug 21-27) * Much of the SECCHI data taken during the solar eclipse yesterday (Aug 21) was downloaded this morning (Aug 22). About 25% of the in situ data remains onboard, along with 30% of the SECCHI SSR1 buffer, and 89% of the SECCHI SSR2 buffer. The remaining data may come down tonight, or else tomorrow (Aug 23). * The APL station tracked STEREO Ahead during the eclipse, bringing down real-time beacon data. Some of this material may have ended up in a NOVA presentation the evening after the eclipse. * Command uplink was lost temporarily during yesterday's (Aug 21) support for Behind. This happened at 13:35 UT, which was 1 hour and 15 minutes into the support. The battery recovery sequence was underway at the time. The sequence was picked back up again once uplink was restored. * Ahead has 9 tracks during the week, and overall coverage is nominal. There are eight tracks at 720 kbps, and one at 240 kbps. * Recovery tracks switch to a daily cadence (~4-hours 70-m time each day). During the first two days, will use a different frequency acquisition sequence (using 1 kHz steps and going down 18 steps and then back up) in case the transponder has drifted out of the currently used 4kHz range. Anticipate using this finer frequency resolution the first two days of each week, with the first track being for battery recovery, and the second track being for carrier recovery. The Radio Science Receiver will be operating during all tracks. Week 35 (Aug 28-Sep 3) * The STEREO Behind recovery review will be held at APL on Tuesday, Aug 29. See above for details. * The 40th SECCHI stepped calibration roll on Ahead is scheduled for Tuesday, Aug 29, starting at 11:55 UT. This is for the midpoint in the orbit. System momentum is expected to be 6 N-m-s. This will be the 9th stepped roll without using the gyros. * On Wednesday, Aug 30, The DSN will be conducting a test of a conical search pattern of 0.048 degrees that may be used later in the year to search for the Behind spacecraft, if needed. * 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, with the older frequency acquisition sequence with the finer 1 kHz steps used on Monday and Tuesday, with the first track being for battery recovery, and the second track being for carrier recovery. 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 2.5-4 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 test track may be taken out of the schedule if the earlier track is successful. * 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. 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 7 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. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 34: M Aug 21 (233) Begin daily Behind recovery tracks Solar eclipse in the United States T Aug 22 (234) W Aug 23 (235) T Aug 24 (236) F Aug 25 (237) S Aug 26 (238) S Aug 27 (239) Note: * 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. * Extra SECCHI coronagraph images during the eclipse. ------------------------------------------------------------------------------- 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 (TBC) 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. ------------------------------------------------------------------------------- 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