STEREO Weekly Meeting Minutes for 2017-09-19 (Week 38) 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. * The MOC will need to be powered down for about 12 hours to fix a recent problem that affected the TIMED mission. The scheduling for this work will be arranged to minimize the impact, and will likely take place sometime in October. Instrument teams will drop connections when the power goes out, and will need to reconnect once power is restored. The MOC will keep everyone advised with the plans for this work. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 37 (Sep 11-17) * On day 254 (Sep 11), during the DSS-14 support for Ahead, the station transmitter power output decreased from 9.75 kW to 4.4 kW at 1709z. The power level was re-adjusted to 10 kW at 1721z. This anomaly resulted in the loss of 24 frames of SSR data due to downlink shifting in and out of coherency. See DR #G118444 for more information. * On day 257 (Sep 14), during the DSS-43 support for Ahead, turbo decoder lock was lost intermittently between 2205z and 2213z. While this anomaly resulted in the loss of 10,260 frames of real-time and SSR data, SSR pointers were repositioned and all SSR data were recovered. See DR# C112920 for more information. * On day 259 (Sep 16), during the DSS-63 support for Ahead, the primary command workstation in the MOC restarted unexpectedly at 1407z, after completion of command activities. The backup command workstations continued to monitor the remaining 33 minutes of the support. The primary command workstation was restored after EOT, at 1619z. All command activities were completed satisfactory and all SSR data was recovered. * The average daily science data return for Ahead was 6.2 Gbits during this week. * Daily attempts to recover Behind were carried out during the week. No carrier signal was detected. Details are below. Daily attempts will continue until Nov 5. * A newly developed honeycomb search pattern with 0.048 degree steps was successfully tested on Wednesday, Sep 14. There will be a telecon at 1:00 today (Sep 19) to discuss how to use this new capability. * On day 254 (Sep 11), 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 255 (Sep 12), during a 3.3 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 256 (Sep 13), during a 3.4 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. A newly developed expanding honeycomb search pattern with 0.048 degree steps and 40 second dwells was tested successfully during this track. 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 257 (Sep 14), during a 2.5 hour support for Behind with DSS-14, 189 commands were transmitted for battery state of charge recovery. Due to the duration of the support, only 21 of the 36 frequency segments were commanded. * On day 258 (Sep 15), 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 259 (Sep 16), during a 4 hour support for Behind with DSS-14, 389 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 260 (Sep 17), during a 4 hour support for Behind with DSS-63, 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 38 (Sep 18-24) * The demo track originally scheduled for Thursday, Sep 21, has been postponed until later, possibly in November. * Behind reached perihelion on Sep 18. * Ahead has 8 tracks during the week, all at 720 kbps, and overall coverage is nominal. * Recovery tracks for Behind are scheduled every day with 70-m antenna, of 3-4 hour durations with the 1 kHz frequency segmented acquisition sequence being used on Monday for battery recovery and Tuesday 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 seven tracks at 720 kbps, one at 240 kbps, and two at 160 kbps. * Recovery tracks for Behind are scheduled every day using the 70-m antenna, of 3-3.8 hour durations with the 1 kHz frequency segmented acquisition sequence being used on Monday for battery recovery and Tuesday for carrier recovery. Week 40 (Oct 2-8) * Ahead has 13 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, three at 240 kbps, and three at 160 kbps. * Recovery tracks for Behind are scheduled every day using the 70-m antenna, of 3-4 hour durations with the 1 kHz frequency segmented acquisition sequence being used on Monday for battery recovery and Tuesday 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 12 tracks during the week, and overall coverage is nominal. There are five tracks at 720 kbps, two at 240 kbps, and five at 160 kbps. * Recovery tracks for Behind are scheduled every day using the 70-m antenna, of 2.5-4 hour durations with the 1 kHz frequency segmented acquisition sequence being used on Monday for battery recovery and Tuesday for carrier recovery. Week 42 (Oct 16-22) * Four ESA stations will be used three times during the week, including both New Norcia and Malargue stations. * Ahead has 16 tracks during the week, and overall coverage is nominal. There are three tracks at 720 kbps, two at 240 kbps, and eleven at 160 kbps. * Recovery tracks for Behind are scheduled every day using the 70-m antenna, of 2.5-3.7 hour durations with the 1 kHz frequency segmented acquisition sequence being used on Thursday for battery recovery and Friday for carrier recovery. Week 43 (Oct 23-29) * 11th launch anniversary of the STEREO mission on Oct. 25th. * Ahead has 19 tracks during the week, and overall coverage is nominal. There are three tracks at 720 kbps, four at 240 kbps, and twelve at 160 kbps (two tracks are using ESA stations). * Recovery tracks for Behind are scheduled every day using the 70-m antenna, of 2.5-4 hour durations with the 1 kHz frequency segmented acquisition sequence being used on Tuesday for battery recovery and Wednesday for carrier recovery. Week 44 (Oct 30-Nov 5) * Daily standard time in the US ends on Sunday, Nov 5. * Ahead has 16 tracks during the week, and overall coverage is nominal. There are two tracks at 720 kbps, three at 240 kbps, and eleven at 160 kbps. * This is the last week of daily attempts to contact Behind. Recovery tracks are scheduled every day using 70 m stations, of 2-3.2 hour durations. DSN time starting this week is very contentious due to the line-up of multiple missions in the same region of the sky, and the fact that only two 70 meter DSN dishes are operating. The 1 kHz frequence segmented acquisition sequence will be used on Tuesday for battery recovery, and Wednesday for carrier recovery. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 38: M Sep 18 (261) Behind: Perihelion T Sep 19 (262) W Sep 20 (263) T Sep 21 (264) 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. ------------------------------------------------------------------------------- Scheduled activities for Week 43: M Oct 23 (296) T Oct 24 (297) W Oct 25 (298) 11th anniversary of STEREO launch T Oct 26 (299) F Oct 27 (300) S Oct 28 (301) S Oct 29 (302) 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 44: M Oct 30 (303) T Oct 31 (304) W Nov 01 (305) T Nov 02 (306) F Nov 03 (307) S Nov 04 (308) S Nov 05 (309) Daylight savings time ends in US 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. ------------------------------------------------------------------------------- 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