STEREO Weekly Meeting Minutes for 2014-08-12 (Week 33) ANNOUNCEMENTS ------------- * See discussion below about timeline of Ahead operations on Aug 19. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 32 (Aug 4-10) * On day 216 (Aug 4), the 70th momentum dump on Ahead was executed successfully at 1800z, which imparted a delta V of 0.0861 m/sec. Note that the momentum target was set lower, 8 Nms, rather than the typical 15 Nms, to allow for the last SECCHI Stepped Calibration before side lobe operations commence on Ahead on August 20th. * On day 217 (Aug 5), the long duration (11 months) ephemeris, to be used for solar conjunction, was loaded to G&C RAM on Ahead, in preparations for side lobe operations. * On day 218 (Aug 6), a Side Lobe Real-time Telemetry Test was conducted on Ahead and provided good feedback for real-time science data return during side lobe operations. The averaged real-time telemetry rates were at or better than required and space weather beacon data was received for all instruments for the three tested configurations. However, there were instrument science and housekeeping data dropouts during the spacecraft SSR playback portions of both first side lobe tests. Within the RTDFD tables, these rows are at the bottom of the table and therefore will be affected by any imbalance in the telemetry data flow. At this very low telemetry rate, 10 kbps, the playback ratio is set as low as possible, at one. Therefore, the downlink is split between the playback and real-time telemetry until the playback completes or the SSR empties. The combined instrument real-time telemetry rate is set for 7.2 kbps. For the second side lobe test, at 3 kbps, for which no dropouts occurred, the combined instrument real-time telemetry rate is set for 1.7 kbps, roughly half the downlink rate. At the start of the test, the spooler buffer queues, which buffer all real-time telemetry, were not cleared as there is no capability to do so. The spooler buffer queues are sized for the prime science real-time downlink rates. These buffers are dynamically allocated when the C&DH FSW application is loaded and can only be reallocated after a system reset of the observatory. The spooler buffer queue table could be changed to minimize the data dropouts but not ensure eliminating them, before loading and resetting the observatory, as the fidelity of the hardware simulator/flatsat is insufficient. Note that each observatory will be on the first side lobe for approximately five months total. Operational solutions to eliminate the data dropouts are being investigated. * On day 222 (Aug 10), the SECCHI instrument on Ahead reset at 20:14:57z. The SECCHI team reconfigured the instrument to operational mode at 1000z. This was the 36th reset of SECCHI on the Ahead spacecraft. * On day 216 (Aug 4), during the DSS-63 support for Behind, real-time telemetry reception was lost at the MOC for three minutes beginning at 1249z due to a DCD fault tolerance anomaly at the station. The DSN switched to the backup DCD to correct. All SSR data was received. See DR #N109681 for more information. * On day 221 (Aug 9), during the DSS-43 support for Behind, turbo decoder lock was lost intermittently beginning at 2345z through 2349z. This anomaly resulted in the loss of 28 frames of SSR data. * On day 216 (Aug 4), C&DH FSW version 3.2.4 was loaded to EEPROM, copy 2, on Behind in preparations for solar conjunction testing. * The average daily SSR playback volume during the week was 5.3 gigabits for Ahead, and 5.0 gigabits for Behind. Week 33 (Aug 11-17) * The long duration ephemeris will be uploaded to EEPROM on Ahead later today (Aug 12), to cover the solar conjunction period. * The 31st SECCHI stepped calibration roll on Ahead will be on Tuesday, Aug 12, starting at 17:50 UT. * The 4th battery discharge/charge cycle on Ahead will be Thursday, Aug 14, starting at 15:00 UT. This will not affect science operations. These battery conditioning operations are carried out each year near aphelion. * MOps macro release 1.1.23, and data handling release 1.1.8 will be written to EEPROM on Ahead on Friday, Aug 15. * Ahead will be at aphelion on Saturday, Aug 16. * A PIT test was carried out yesterday with Behind on station 26 to test out new DSN software. * Ahead has 8 passes during the week, all at 480 kbps, and overall coverage is nominal. * Behind has 13 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, one pass at 240 kbps, two passes at 160 kbps, and seven passes at 120 kbps. * Current HGA feed temperatures are 115.9 degrees on Ahead, at an SPE angle of 7.5 degrees, and 98.0 degrees on Behind, at an SPE angle of 9.3 degrees. Week 34 (Aug 18-24) * The Ahead reconfiguration for side-lobe operations will be loaded on Tuesday Aug 19. Final mission operation macros and the HDA angle bias will be loaded. The SSR will be reconfigured. A timeline has been sent to the instrument teams. The instrument teams are requested to switch to their side lobe telemetry rates starting at 00:00 UT on Tuesday, Aug 19. This will help with emptying the SSR partitions, which needs to be done before SSR reconfiguration to avoid losing data. It takes about 3 hours to reconfigure the spacecraft. At the end of the track, the HGA antenna will be moved by 3.2 degrees to put it on the first side lobe. * Ahead operations on the first side lobe will start Aug 20 on station 14, in IMPACT-prime mode. * In the absence of moving to side lobe operations, the HGA soft stop angle of 7.1 degrees on Ahead would be reached on Aug 23. * Ahead has 8 passes during the week, and overall coverage is nominal. There are two passes at 360 kbps (Monday and Tuesday). On Aug 20th 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. 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. * 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. Other * It was pointed out that the SOHO project is having trouble getting sufficient antenna coverage during weeks 45-48, mainly due to MESSENGER activities. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 33: M Aug 11 (223) Ahead: Recovery from SECCHI watchdog reset, 10:00 UT T Aug 12 (224) Ahead: SECCHI stepped calibration roll, 17:50 UT W Aug 13 (225) T Aug 14 (226) Ahead: Battery conditioning F Aug 15 (227) S Aug 16 (228) Ahead: Aphelion S Aug 17 (229) ------------------------------------------------------------------------------- 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 Behind: Momentum dump, 18:30 UT T Aug 26 (238) W Aug 27 (239) T Aug 28 (240) F Aug 29 (241) 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 ------------------------------------------------------------------------------- Upcoming events: 2014: * Sep 07-Nov 15 Behind: Passage of Comet Siding Spring through HI2-B * Sep 21 MAVEN arrival at Mars * Sep 29-Oct 6 Behind: Test of solar conjunction operations * 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