STEREO Weekly Meeting Minutes for 2017-09-26 (Week 39) ANNOUNCEMENTS ------------- * The time history ancillary product is not being updated. The MOC is looking into the problem. Time keeping on the spacecraft is still being maintained. Also, the as-run track plan has not been generated since Friday (Sep 22). 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. * A diamond shaped search pattern has been added to the Behind recovery effort, based on the estimated uncertainty in the ephemeris. The diamond pattern is executed twice, once to send commands to turn on the transmitter, and then again 40 minutes later to listen for the carrier. This search pattern will be run twice a week, with the first attempt tomorrow (Sep 27). DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 38 (Sep 18-24) * On day 267 (Sep 24), during the DSS-63 support for Ahead, there was no uplink for this track as the transmitter was declared red on day 265. This anomaly resulted in the loss of 3.3 hours of commanding and two-way tracking data. See DRs #M110227 for more information. * The average daily science data return for Ahead was 6.2 Gbits during this week. * On day 261 (Sep 18), during a 3 hour support for Behind with DSS-14, 225 commands were transmitted for battery state of charge recovery. Due to the duration of the support, only 25 of the 36 frequency segments were commanded. * On day 262 (Sep 19), during a 4 hours support 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 263 (Sep 20), during a 3.5 hour support for Behind with DSS-14, 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 264 (Sep 21), during a 4 hour support for Behind with DSS-43, 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 265 (Sep 22), during a 4 hour support for Behind with DSS-43, 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 266 (Sep 23), during a 4 hour support for Behind with DSS-14, 401 commands were transmitted during the support. Between 1417z and 1424z, an issue with the transmitter prevented commands from radiating. This anomaly resulted in 19 battery recovery commands not being transmitted. See DR# G118485 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 267 (Sep 24), during a 4 hour support for Behind with DSS-14, the uplink was delayed 73 minutes due to a transmitter calibration issue. The issue was resolved at 1348z and 282 commands were transmitted during the support. See DR #G118487 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. Week 39 (Sep 25-Oct 1) * The current extended mission #3 officially ends on Sep 30. The Senior Review is ongoing. * The first diamond shaped search patterns for Behind will be executed tomorrow (Sep 27), and Friday (Sep 29). * 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. Diamond shaped search patterns will be used on Wednesday and Thursday. 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. Diamond shaped search patterns will be used on Thursday and Friday. 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. Diamond shaped search patterns will be used on Monday and Wednesday. * The DSN commented that uplink transfer between DSN and ESA stations has been tested out, and is available for STEREO use if needed. 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. Diamond shaped search patterns will be used on Monday and Thursday. 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. Diamond shaped search patterns will be used on Monday and Friday. Week 45 (Nov 6-12) * Ahead has 18 tracks during the week, and overall coverage is nominal. There are two tracks at 720 kbps, three at 240 kbps, and thirteen at 160 kbps. Four of these tracks use ESA stations. * Tracks to recover Behind switch to a weekly schedule, with tracks scheduled to keep within the 3 day onboard timer. Behind recovery tracks are scheduled for Tuesday, Friday, and Saturday. * A question was raised as to whether or not the diamond shaped search pattern would be used with the weekly recovery schedule. This is still being looked into. Other * The power system in the building containing the MOC will need to be shut down for maintenance for 1-2 days. The anticipation is that generators will be brought in to keep the MOC running, but planning is still ongoing. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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. Diamond shaped search patterns on Wednesday and Friday. ------------------------------------------------------------------------------- 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. Diamond shaped search patterns on Wednesday and Thursday. ------------------------------------------------------------------------------- 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. Diamond shaped search patterns on Thursday and Friday. ------------------------------------------------------------------------------- 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. Diamond shaped search patterns on Monday and Wednesday. ------------------------------------------------------------------------------- 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. Diamond shaped search patterns on Monday and Thursday. ------------------------------------------------------------------------------- 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. Diamond shaped search patterns on Monday and Friday. ------------------------------------------------------------------------------- Scheduled activities for Week 45: M Nov 06 (310) T Nov 07 (311) Behind: Recovery track with station 14 W Nov 08 (312) T Nov 09 (313) F Nov 10 (314) Behind: Recovery track with station 14 S Nov 11 (315) Behind: Recovery track with station 14 S Nov 12 (316) Notes: * Behind recovery attempts switch back to weekly, roughly every 2-3 days. ------------------------------------------------------------------------------- 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