STEREO Weekly Meeting Minutes for 2014-08-19 (Week 34) ANNOUNCEMENTS ------------- * See the discussion below about stored command buffer dumps, and other steps being taken to minimize telemetry dropouts during side-lobe operations. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 33 (Aug 11-17) * On day 224 (Aug 12), the long duration (11 months) ephemeris, to be used for solar conjunction, was loaded to G&C EEPROM on Ahead, in preparations for side lobe operations and solar conjunction. * On day 224 (Aug 12), the 31st SECCHI stepped calibration roll on Ahead was executed at 1750z for aphelion in the orbit. This will be the last calibration roll on Ahead until normal operations are resumed in 2016. * On day 226 (Aug 14), the 4th battery conditioning event was successfully conducted on the Ahead spacecraft to redistribute the electrolytes within the nickel hydrogen battery cells. * On day 227 (Aug 15), DHS parameters version 1.1.8 and MOps macros 1.1.23 were loaded to EEPROM in preparations for SSR reconfiguration to support Ahead side lobe operations which will commence on day 232 (Aug 20). * On day 223 (Aug 11), an Uplink Tracking and Command (UPL) v11.3 Project Interface Test (PIT) was conducted on Behind with DSS-26. The purpose was to validate DSN to Project functional interfaces with UPL V11.3 software. All test objectives were met successfully. Tracking, telemetry, and command data from this support was non-committed. * On day 226 (Aug 14), during the DSS-55 support for Behind, command bind was lost at 0842z. The MOC rebound the command link. Later in the support, real-time telemetry reception was lost at the MOC for two minutes beginning at 1041z due to a DCD fault tolerance anomaly at the station. The DSN switched to the backup DCD to correct. All SSR data were received. See DR #N109695 for more information. * On day 227 (Aug 15), during the DSS-26 support for Behind, initial telemetry lock was established 32 minutes late at 1632z due to a failed UPS unit for the LNA at the station. The DSN switched to the backup UPS unit to correct. Later in the support, the downlink receiver lost telemetry beginning at 1730z for 45 minutes. A backup receiver channel was added to correct. All SSR data were received for this track. However, SECCHI partition 19 later filled due to these anomalies. See DRs #G115353 and #G115354 for more information. * On day 228 (Aug 16), during the DSS-25 support for Beind, turbo decoder lock was lost briefly beginning at 1822z. This anomaly resulted in the loss of two frames of SSR data. * On day 229 (Aug 17), during the DSS-25 support for Behind, turbo decoder lock was lost briefly beginning at 1823z. This anomaly resulted in the loss of 11 frames of SSR data. * On day 228 (Aug 16), the SSR science partitions on Behind filled as follows: SECCHI (Part 19) reached 100% full at 0309z for 5.2 hours. The cause for the partition filling was the DSS-26 LNA anomaly and SSR pointer repositioning on day 227. * The average daily SSR playback volume during the week was 4.6 gigabits on Ahead, and 4.1 gigabits on Behind. * The current HGA feed horn temperatures are 116.9 degrees on Ahead, at an SPE angle of 7.2 degrees, and 96.0 degrees on Behind, at an SPE angle of 9.4 degrees. The temperature on Ahead will drop significantly after the 3.2 degree HGA offset to the first side band later today (Aug 19). * The have been some discussions about minimizing telemetry dropouts during side lobe operations, particularly in regards to SECCHI images which come down as a series of packets. One operation which was discussed was the dumping of the stored command buffer, where time-tagged commands for some of the instruments are stored. During normal operations, this buffer is dumped every pass. However, at the low rates for side lobe operations, dumping this buffer has the potential to disrupt the real time telemetry from the instruments for 20-60 seconds. The MOC proposed instead that this buffer only be dumped on request, and the instrument teams have agreed to this. * A telecon was held with the SECCHI team about strategies to minimize the effects of telemetry dropouts on their image data. Two kinds of dropouts were seen during the recent testing. The playback of spacecraft housekeeping data from the SSR at the 10 kbps rate caused the spooler buffer queues to fill up, leading to telemetry dropouts for all the instruments for several minutes. Following this is the uplink sweep from the DSN station, which disrupts the telemetry for about 1.5 minutes. This occurs about 8-9 minutes from the start of every pass, plus the one-way light travel time. The present solution for keeping these dropouts from degrading SECCHI data is for SECCHI to wait until about 30 minutes into the pass, until the end of the uplink sweep. Week 34 (Aug 18-24) * Ahead operations on the first side lobe will start tomorrow (Aug 20) on station 14, in IMPACT-prime mode. * The IMPACT SWEA/STE power service on Ahead has been switched off; these will not be used during side lobe operations. * The instrument data has been played back from the SSR on Ahead, and reconfiguration of the SSR has begun. The MOC appreciates the instrument teams dialing back their data rate at the start of the UT day to assist in getting all the data off the recorder. * Switching to the 1st side lobe on Ahead is anticipated to occur about 3 PM EDT (~19 UT) this afternoon. * Ahead has 8 passes during the week, and overall coverage is nominal. The first two passes are at 360 kbps (Monday) and at 720 kbps (Tuesday). On Aug 20 first side lobe coverage will begin and be at 10 kbps. This will continue until around Nov 10 when operations on the second side lobe will bring this down to 3 kbps. * Behind has 14 passes during the week, with nominal coverage overall. Four tracks are at 720 kbps, one at 160 kbps and nine at 120 kbps. Week 35 (Aug 25-31) * Ahead will be operating with the high gain antenna on its first side lobe, switching to SWAVES-prime mode. * A test of using a 34 meter station at 633 bps with Ahead will be carried out on Monday, Aug 25, using both 1st and 2nd side lobes. Spacecraft housekeeping will come down during this pass, not space weather beacon data. The primary purpose of this test is to determine whether 34 meter stations can be used in case of a spacecraft emergency. If the spacecraft resets, it will automatically come back up at 633 bps. If the test is successful, it also opens up the possibility of using 34 meter stations for space weather data. The project would need to determine whether they wish to consider pursuing this option, considering that DSN time is charged to the project. * The 66th momentum dump for Behind is Monday, Aug 25 at 18:30 UT. * The 71st momentum dump for Ahead is Friday, Aug 29, starting at 00:30 UT. This will be the send momentum dump carried out on the antenna side lobe. * Ahead has 9 passes during the week, eight at 10 kbps, and one at 633 bps. * Behind has 11 passes during the week, and overall coverage is nominal. Six passes are at 720 kbps, one at 240 kbps, two at 160 kbps, and two at 120 kbps. Week 36 (Sep 1-7) * Monday, September 1, is the Labor Day holiday. * Ahead has 8 passes during the week, all at 10 kbps on the first side lobe, in IMPACT-prime mode. * Behind has 13 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, three passes at 160 kbps, and eight passes at 120 kbps. Week 37 (Sep 8-14) * Ahead has 7 passes during the week, all at 10 kbps on the first side lobe, in SWAVES-prime mode. * Behind has 12 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, two passes at 160 kbps, and eight passes at 120 kbps. Week 38 (Sep 15-21) * Ahead has 7 passes during the week, all at 10 kbps on the first side lobe, in IMPACT-prime mode. * Behind has 13 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, four passes at 160 kbps, and seven passes at 120 kbps. Week 39 (Sep 22-28) * The solar conjunction testing for the Behind spacecraft may begin late in the week. * Ahead has 8 passes during the week, all at 10 kbps on the first side lobe, in SWAVES-prime mode. * Behind has 13 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, four passes at 160 kbps, and seven passes at 120 kbps. ESA New Norcia passes are scheduled for Monday, Sep 22, and Wednesday, Sep 24. Week 40 (Sep 29-Oct 5) * Solar conjunction testing will be carried out on Behind during the week. This test will replicate the earlier testing done on Ahead, July 6-11. All science instruments will be off during this test. * Ahead has 9 passes during the week, all at 10 kbps on the first side lobe, in IMPACT-prime mode. * Behind has seven passes during the week, all 70 meter stations, for solar conjunction testing. Week 41 (Oct 6-12) * Ahead has seven passes during the week, all at 10 kbps on the first side lobe, in IMPACT prime mode. * Behind has 13 passes during the week, and overall coverage is nominal. There are five passes at 720 kbps, two passes at 160 kbps, and six passes at 120 kbps. An ESA New Norcia pass is scheduled for Wednesday, Oct 8. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 34: M Aug 18 (230) T Aug 19 (231) Ahead: SSR reconfiguration W Aug 20 (232) Ahead: HGA on 1st side lobe, in IMPACT-prime mode T Aug 21 (233) F Aug 22 (234) S Aug 23 (235) S Aug 24 (236) ------------------------------------------------------------------------------- Scheduled activities for Week 35: M Aug 25 (237) Ahead: Test with 34 meter at 633 bps, both side lobes Behind: Momentum dump, 18:30 UT T Aug 26 (238) W Aug 27 (239) T Aug 28 (240) F Aug 29 (241) Ahead: Momentum dump, 00:30 UT S Aug 30 (242) S Aug 31 (243) Notes: * Ahead operating on first side lobe, in SWAVES-prime mode. ------------------------------------------------------------------------------- Scheduled activities for Week 36: M Sep 01 (244) Labor Day T Sep 02 (245) W Sep 03 (246) T Sep 04 (247) F Sep 05 (248) S Sep 06 (249) S Sep 07 (250) Notes: * Ahead operating on first side lobe, in IMPACT-prime mode. * Passage of Comet Siding Spring through HI2 on Behind, Sep 07-Nov 15 ------------------------------------------------------------------------------- Scheduled activities for Week 37: M Sep 08 (251) T Sep 09 (252) W Sep 10 (253) T Sep 11 (254) F Sep 12 (255) S Sep 13 (256) S Sep 14 (257) Notes: * Ahead operating on first side lobe, in SWAVES-prime mode. * Passage of Comet Siding Spring through HI2 on Behind, Sep 07-Nov 15 ------------------------------------------------------------------------------- Scheduled activities for Week 38: M Sep 15 (258) T Sep 16 (259) W Sep 17 (260) T Sep 18 (261) F Sep 19 (262) S Sep 20 (263) S Sep 21 (264) MAVEN arrival at Mars Notes: * Ahead operating on first side lobe, in IMPACT-prime mode. * Passage of Comet Siding Spring through HI2 on Behind, Sep 07-Nov 15 ------------------------------------------------------------------------------- Scheduled activities for Week 39: M Sep 22 (265) T Sep 23 (266) W Sep 24 (267) T Sep 25 (268) F Sep 26 (269) S Sep 27 (270) S Sep 28 (271) Notes: * Ahead operating on first side lobe, in SWAVES-prime mode. * Passage of Comet Siding Spring through HI2 on Behind, Sep 07-Nov 15 * Solar conjunction testing on Behind may start toward end of week. ------------------------------------------------------------------------------- Scheduled activities for Week 40: M Sep 29 (272) Behind: Start of solar conjunction testing T Sep 30 (273) W Oct 01 (274) T Oct 02 (275) F Oct 03 (276) S Oct 04 (277) S Oct 05 (278) Notes: * Ahead operating on first side lobe, in IMPACT-prime mode. * Test of solar conjunction operations on Behind, Sep 29-Oct 6 * Passage of Comet Siding Spring through HI2 on Behind, Sep 07-Nov 15 ------------------------------------------------------------------------------- Scheduled activities for Week 41: M Oct 06 (279) Behind: End of solar conjunction testing T Oct 07 (280) W Oct 08 (281) T Oct 09 (282) F Oct 10 (283) S Oct 11 (284) S Oct 12 (285) Notes: * Ahead operating on first side lobe, in IMPACT-prime mode. * Test of solar conjunction operations on Behind, Sep 29-Oct 6 * Passage of Comet Siding Spring through HI2 on Behind, Sep 07-Nov 15 ------------------------------------------------------------------------------- Upcoming events: 2014: * Sep 07-Nov 15 Behind: Passage of Comet Siding Spring through HI2-B * Oct 17 Behind: Comet Siding Spring encounter with Mars * Oct 23 Both: Solar Conjunction Readiness Review * Nov 10 Ahead: HGA on 2nd side lobe * Nov 17 Ahead: Test with 34 meter at 633 bps * Nov 19 Behind: HGA hits soft stop * Nov 28 Behind: SSR reconfiguration * Dec 1 Behind: HGA on 1st side lobe * Dec 8 Behind: Test with 34 meter at 633 bps 2015: * Jan 6 Behind: HGA on 2nd side lobe * Jan 12 Behind: Test with 34 meter at 633 bps * Jan 20 Behind: Instrument power down * Jan 22 - Mar 23 Behind: Spacecraft behind Sun * Mar DAWN - Ceres arrival * Mar 22 Ahead: Instrument power down * Mar 23 - Apr 06 Behind: S/C SSR Playback at 3 kbps * Mar 24 - Jul 07 Ahead: Spacecraft behind Sun * Mar 30 Behind: Instrument power on * Apr 25 Behind: HGA on 1st side lobe * Jul DAWN - End of nominal mission * Jul 8 Behind: HGA on 2nd side lobe * Jul 7-28 Ahead: S/C SSR Playback at 3 kbps * Jul 14 Ahead: Instrument power on * Sep 24 Ahead: HGA on 1st side lobe * Nov 20 Behind: HGA on 1st side lobe * Dec 29 Ahead: HGA on main lobe, offpoint 1 degree Ahead: SSR playback and reconfiguration, S/C checkout * Dec 31 Ahead: Instrument recommissioning 2016: * Jan 2 Behind: HGA on main lobe Behind: SSR playback and reconfiguration, S/C checkout * Jan 5 Behind: Instrument recommissioning * Jan 27 Both: HGA calibration * Feb 19 Ahead: HGA on main lobe * Mar 16 Both: Post Solar Conjunction Assessment Review * Jul 5 Juno arrival at Jupiter 2017: * Jul 11 Ahead: Switch downlink rate to 160 kbps * Jul 22 Behind: Switch downlink rate to 160 kbps 2018: * Mar 5 Ahead: Mercury transit