STEREO Weekly Meeting Minutes for 2014-08-26 (Week 35) ANNOUNCEMENTS ------------- * None. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 34 (Aug 18-24) * On day 232 (Aug 20), during the DSS-14 support for Ahead, which was the first side lobe operational track, ranging lock was lost intermittently beginning at 1708z through 1915z. During the week, the same issue occurred at all three DSN complexes. Low ranging margin is a known issue for side lobe operations and the FDF can meet ephemeris accuracy requirements using Doppler data only. See DR #G115365, #M108275, and #C110502 for more information. * On day 233 (Aug 21), during the DSS-14 support for Ahead, turbo decoder lock was lost briefly beginning at 1746z and 1748z. This anomaly resulted in the loss of two frames of SSR data. See DR #G115376 for more information. * On day 231 (Aug 19), in preparations for Ahead side lobe operations, instrument switched to their first side lobe telemetry generation rates at 0000z. Later this day, during the DSS14 support, the IMPACT SWEA/STE instruments were powered off at 1430z, the SSR was emptied, loaded DHS parameters version 1.1.8 to C&DH RAM, reconfigured the SSR partitions, and the HGA was positioned to the first side lobe. * On day 232 (Aug 20), during the DSS-14 support for Ahead, side lobe operations commenced on the Ahead observatory to mitigate HGA feed overheating. The received downlink signal was good with 5 dB of margin with a starting elevation of 43 degrees and rising. The spacecraft SSR playback only returned half the expected data volume. The spacecraft SSR playback duration was increased 14 minutes to stop when the SECCHI imaging schedule commences and the playback ratio was increased to two to correct. * On day 231 (Aug 19), during the DSS-65 support for Behind, turbo decoder lock was lost briefly beginning at 1549z. This anomaly resulted in the loss of one frame of SSR data. * On day 233 (Aug 21), during the DSS-25 support for Behind, command bind was lost at 1708z. The MOC rebound the command link. All SSR data were received. See DR #G115374 for more information. * The average daily SSR playback volume during the week was 1.1 gigabits for Ahead, and 4.5 gigabits for Behind. * The SSC reported a number of gaps in the instrument data from Behind starting on Aug 22 and continuing for the next several days. The MOC reports finding some IDR files that hadn't been incorporated into the level-0 telemetry files, and will reprocess the files. * The HGA feed horn temperature on Ahead dropped from a high of 118 C to the present value of 99 C after switching to the first side lobe. The current antenna angle to the Sun is 10.2 degrees. The feed horn temperature on Behind is 96 C at an antenna angle of 9.4 degrees. The temperatures on both spacecraft are expected to gradually increase again. * The FDF performed a study of orbit propagation errors to make sure that the orbit will still be adequately known as it passes behind the Sun. The study was conservative, as it didn't take data from the momentum dumps into consideration. The propagation errors were found to be within specification. 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 download, 125 bps upload with Ahead was carried out yesterday (Aug 25), using both 1st and 2nd side lobes. This test worked out well. The signal had 8 dB of margin on the first side lobe, with an elevation starting at 30 degrees and rising during the test. This margin dropped to 2 dB during the second side lobe test, at a higher elevation angle, but the DSN was still able to lock up. This establishes the DSN (and possibly ESA) 34 meter stations as a viable option for contingency operations. It also opens up the possibility of using the 34 meter stations for bringing down space weather data. * MOps macro release 1.1.24 was loaded to C&DH RAM on the Ahead spacecraft this morning. * 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. * The 66th momentum dump for Behind was carried out succesfully yesterday (Aug 25). * Preparations begin for solar conjunction on Behind. DHS parameters 1.1.8 and power macros 1.0.3 will be written to C&DH EEPROM on Wednesday, Aug 27. * 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. * G&C parameters 1.3.1 will be loaded to EEPROM on Behind on Tuesday, Sep 2. * 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) * Macros and rules will be written to EEPROM and RAM on Behind from Tuesday to Friday, Sep 23-26. EA mode bypass will be enabled on Thursday, Sep 25. * Solar conjunction testing will start on Saturday, Sep 27. A more detailed schedule will be distributed later. Instruments will be turned off by 18 UT, with the exception of SWAVES which will remain on. SWAVES will be powered cycled twice during the test. POC queues will be open on Friday for instrument commanding. * On Sunday, Sep 28, the HGA angle bias will be switched to the first side lobe. The 67th momentum dump will be carried out during the station 14 pass on the first side lobe, starting at 16:30 UT, with a lower target of 8 N-m-s as will be used during solar conjunction. The spacecraft will reset at 17:30 UT, and will come up at 633 bps, and slowly rotating at 5 degrees/minute. * Ahead has 7 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 on Behind will continue during the week. The earlier testing on Ahead concentrated on the process of going into solar conjuction. These tests will concentrate on the process of coming out. The recorder is also reconfigured during these tests, which was not done during the Ahead testing. * During the first pass on Monday, Sep 29, the MOC will watch the spacecraft rotate. At 05:30 UT a time tagged command will put the spacecraft into 3-axis stabilized mode. * On Tuesday, Sep 30, the 48 hour fault protection rule will trigger at 17:30 UT, switching to the -Z LGA. * On Wednesday, Oct 1, Behind the soft command load timer will trigger at 5:30 UT, switching to the +Z LGA, and start the spacecraft slowly rotating. Station 14 will acquire the signal at 15:30, at 12 bps, and will watch the spacecraft rotate. At 17:50, the 3 day hard command loss timer will trigger, resetting the spacecraft, and setting it back to 3 axis stabilized on the second side lobe. It will then be commanded to a 1 degree offset at 120 kbps, and spacecraft will be reconfigured back to operational mode. * On Thursday, Oct 2, the spacecraft will come up at a 1 degree offset, and will be commanded back to the center of the main lobe. Instrument power on is expected to begin during the station 36 support starting at 15:30 UT. An ESA New Norcia support is also available later in the day, as well as another DSN support and an ESA New Norcia support on Friday. The remainder of the passes during the week will be using 70 meter stations. * Ahead has 9 passes during the week, all at 10 kbps on the first side lobe, in IMPACT-prime mode. * Behind has eleven passes during the week, with seven 70 meter stations, and four 34 meter stations. 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. Other * DSN suggested changing some parameters to allow them to better lock on the ranging data in the first side lobe. This would increase the sampling time from 2 minutes to 6 minutes. FDF agreed that this would help with their orbit determinations. The same technique applied to the second side lobe would probably require even longer sampling times. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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) Behind: Instruments off for solar conjunction testing, 18 UT (except SWAVES) S Sep 28 (271) Behind: Switch to first side lobe. Momentum dump, 16:30 UT. Spacecraft reset at 17:30 UT, come up at 633 bps, rotating 5 degrees/minute. Notes: * Test of solar conjunction operations on Behind, Sep 27-Oct 3 * 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 40: M Sep 29 (272) Behind: Solar conjunction testing continues Behind: Timed command to 3-axis stabilized, 5:30 UT T Sep 30 (273) Behind: Switch to -Z LGA, 17:30 UT W Oct 01 (274) Behind: Switch to +Z LGA and start rotating, 5:30 UT Hard command loss timer, 17:50, switch to 3 axis stab. Switch from 2nd side lobe to 1 degree offset, 120 kbps T Oct 02 (275) Behind: Command back to 0 degree offset on main lobe. Recover spacecraft, start powering instruments back on. F Oct 03 (276) Behind: Continue recovery as needed S Oct 04 (277) S Oct 05 (278) Notes: * Test of solar conjunction operations on Behind, Sep 27-Oct 3 * 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 41: M Oct 06 (279) 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. * 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