STEREO Weekly Meeting Minutes for 2015-10-27 (Week 44) ANNOUNCEMENTS ------------- * The MOC RAID array updates previously scheduled for Thursday (Oct 29) have been postponed. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the first side lobe. * There are currently no communications with the Behind spacecraft. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 43 (Oct 19-25) * There were no ground system anomalies during the week. * The Ahead observatory operated nominally during this week on the 1st side lobe of the HGA to prevent overheating of the HGA feed assembly which was at 109 degrees C and decreasing with the HGA angle at 8.9 degrees and increasing, with respect to the spacecraft-Sun line. The observatory will return to the HGA main lobe, riding along a one degree offset, on day 314, November 10th. The 15 months of in-situ instrument science data on the SSR will be played back twice and NOAA antenna partners can once again close the RF link on the space weather broadcast. On day 321, November 17th, instruments will begin reconfiguration for resuming nominal daily science data return. * This week, data for the following days was played back from the C&DH routine SSR partition playback: 2015-290-06:59:43z through 2015-297-08:32:12z * Specifically, this partition contains spacecraft bus data for science analysis and instrument status, i.e., attitude history, instrument thermal interface temperatures, heater performance, etc., which are used to create the attitude history and converted spacecraft housekeeping data products. * The following days have not played back yet: 071 through 133 = 63 days (inclusive) 146 through 231 = 86 days (inclusive) Total = 149 days This partition’s write pointer is being monitored to ensure that these days are not overwritten, which is currently predicted to do so after returning to the HGA main lobe on or about Nov 13th. * Once on the HGA main lobe, the in-situ instrument space weather science SSR data along with the spacecraft housekeeping data will be downlinked twice and verified before the SSR is reconfigured to resume nominal daily science operations. * The average daily science data return for Ahead, while operating on the 1st side lobe of the HGA, was 92 Mbits during this week. * The Behind observatory entered superior solar conjunction at the 2.0 degree SPE angle on day 022. Recovery efforts resumed post solar conjunction on day 124, May 4th through day 178, June 27th, as the spacecraft had cleared solar interference for LGA communications. The Failure Review Board recommendations were implemented consisting of battery state of charge recovery and powering on the downlink carrier. The Green Bank Radio Telescope and the Arecibo Observatory also observed the carrier recovery tracks. To date, no downlink signal has been detected from the Behind observatory since the anomaly occurred. Due to Behind’s retrograde motion causing it to re-enter the region of solar interference, recovery operations have been suspended and will resume on November 30th. * The Failure Review Board’s recommended faster frequency segmented acquisition sequence was tested with the Ahead observatory on day 272, September 29th. All 18 one kHz frequency steps were tested twice. While stepping down through the 1 kHz segments, on segment #9 going down in frequency, the transponder locked to the BLF and accepted 9 no-op commands as expected. An interesting finding, but not unexpected, was that the transponder continued to follow the moving carrier and accept all commands sent for the remaining 27 segments. * Testing of the DSN uplink arraying capability using the Ahead observatory resumed on day 281, October 8th, with the 3rd uplink array test successfully conducted for STEREO using DSS-24 and 25. This test consisted of two 34m stations, each with a 20 kW transmitter using the HGA 1st side lobe with the Ahead observatory with the MOC sending no-op commands. An approximately 6 dBm increase in received signal power was demonstrated, as compared to one 34m uplink, at the spacecraft with all 30 no-op commands being received correctly using the 7.8125 bps uplink rate. The 4th uplink array test is scheduled for day 323, November 19th, testing the phasing of 80 kW and 20 kW transmitters on the HGA main lobe. When the uplink array capability is ready, it will be used to increase the spacecraft received signal power to assist with Behind recovery commanding. * With time the spacecraft range improves RF communications and the ability for other assets to acquire data on Behind. While the STEREO RF link was not designed to be closed beyond 2 AU, as the Earth range is now decreasing, the LGA uplink margin returns to nominal, 6 dB for the 7.8 bps rate, in March 2016 and the LGA downlink margin returns to nominal, 3 dB for the 12 bps rate, in December 2016. Week 44 (Oct 26-Nov 1) * Ahead starts the week at an SPE angle of 5.7 degrees, on the first side lobe, with IMPACT being prime. * The commands for the momentum dump on Monday, Nov 2, will be loaded on Friday, Oct 30. * Daylight savings time ends in the U.S. on Sunday, Nov 1. * Ahead has 14 passes during the week, with seven passes at 10 kbps, and seven passes at 633 bps, with overall space weather coverage of 30%. * Behind starts the week at an SPE angle of 2.4 degrees. There will be no passes for Behind during the week. Week 45 (Nov 2-8) * Ahead starts the week at an SPE angle of 5.9 degrees, on the first side lobe, with SWAVES being prime. * The 81st momentum dump on Ahead will be carried out on Monday, Nov 2, with ignition at 17:30 UT. IMU-2 will be on during this momentum dump. * Ahead has 8 passes during the week. 70 meter coverage is now nominal. There are seven passes at 10 kbps, and one pass at 633 bps, with overall space weather coverage of 13%. * Behind starts the week at an SPE angle of 2.6 degrees. There will be no passes for Behind during the week. Week 46 (Nov 9-15) * Ahead starts the week still on the first side lobe, with IMPACT being prime. * A detailed schedule for the events during the week has been sent out, including command windows for the instruments. * Temporary macros will be loaded to RAM on Monday, Nov 9, to allow higher real-time rates for the instruments during the week. * In spite of the increase in the telemetry rate, the instruments will remain at their first-side-lobe rates throughout the week, until the SSR partitions are reconfigured on Monday, Nov 16. * At the end of the last pass on Monday, Nov 9, the HGA will be switched to the main lobe, with a 1 degree offset. Immediately following this pass ending at 21:55 UT the NOAA antenna partners should be able to lock onto the space weather beacon telemetry. At this point the nominal telemetry rate will be 240 kbps on 70 meter stations, or 30 kbps on 34 meter stations. However, if a 70 meter pass is at high elevation throughout the pass, the telemetry rate can be increased to 360 kbps, which will be the case for all the passes Tuesday through Sunday. * Starting Tuesday, Nov 10, the uplink rate will increase to 2000 bps for all stations. * On Tuesday, Nov 10, the SSR pointers will be moved to start reading out the SSR. The SSR partitions will be read out at least twice between Tuesday and Sunday. * On Sunday, Nov 15, the original macros will be reloaded into RAM to prepare for switching back to nominal operations mode. SECCHI will also perform some real-time commanding to reduce their telemetry rate. This will result in no images being taken from some time before 23:20 UT on Nov 15 until sometime on Nov 16 or 17. The spacecraft will not switch to space weather mode at the end of the pass to give the buffers a chance to empty out. * Ahead has 9 passes during the week, with one pass at 10 kbps, seven passes at 360 kbps, and one pass at 633 bps (on Monday, Nov 9). Overall coverage is nominal. * Behind starts the week at an SPE angle of 2.9 degrees. There will be no passes for Behind during the week. Week 47 (Nov 16-22) * The MOC requested that the instrument teams, particularly SECCHI, hold off on reconfiguring back to normal science operations until Tuesday, Nov 17, to assist with the SSR reconfiguration. The first opportunity for commanding on Tuesday will be at 08:50 UT. * On Monday, Nov 16, during the station 63 pass for Ahead starting at 10:45 UT, the SSR will be emptied and repartitioned. Updated data handling and MOPS macros will be loaded into RAM. The in situ data partitions will be slightly larger than they were before solar conjunction. * Normal science operations will resume on Tuesday, Nov 17, starting with the station 63 pass for Ahead. The IMPACT SWEA and STE instruments will be powered on, and the SECCHI and SWAVES instruments will be allowed to upload schedules. * The nominal pass duration for 70 meter stations will be increased for 3 to 4 hours. * Ahead will start the week at an SPE angle of 6.2 degrees, riding the HGA soft stop. The center of the main lobe will be reached on Dec 30. * All passes during the week will be supported at the MOC. Since the uplink rate will be 2000 bps, all the instruments should be able to share the uplink. * The fourth uplink array test will be carried out on Thursday, Nov 19. This will involve arraying together two stations, one at 80 kW transmitter power, and the other at 20 kW. * On Thursday, Nov 19, the nominal telemetry rate on the 70 meter stations will be increased to 360 kbps. * A return-to-service track for station 55 is scheduled for Saturday, Nov 21. There will be no instrument commanding or SSR playback during this pass. * Ahead has 10 passes during the week, with six passes at 360 kbps, three passes at 240 kbps, and one pass at 30 kbps. Overall coverage is nominal. * Behind starts the week at an SPE angle of 3.2 degrees. There will be no passes for Behind during the week. Week 48 (Nov 23-29) * On Monday, Nov 23, G&C parameter set 1.3.4 will be written to EEPROM. * There was some discussion about whether to perform a SECCHI stepped calibration roll which had been tentatively scheduled for Tuesday, Nov 24. This roll maneuver would have involved turning on IMU-2. After some discussion, it was decided to not perform the roll maneuver, and wait until January when calibration rolls can be done without the IMU. * APL will be closed for the Thanksgiving holiday Thursday and Friday, Nov 26-27. * Ahead has 9 passes during the week, all at 360 kbps, and overall coverage is nominal. * Behind starts the week at an SPE angle of 3.5 degrees. There will be no passes for Behind during the week. Recovery operations resume the following week. Week 49 (Nov 30-Dec 6) * Ahead starts the week at an SPE angle of 6.5 degrees, riding the HGA soft stop. * The nominal rate on Ahead for 70 meter stations will increase to 480 kbps. * On Monday, Nov 30, data handing and macro parameters will be written to EEPROM. * Ahead has 7 passes during the week, all at 480 kbps, and overall coverage is nominal. * Behind starts the week at an SPE angle of 3.9 degrees. * Behind recovery operations resume on Monday, Nov 30. There will be three passes over three days each week. The first two passes, both 4.5 hours, on Monday, Nov 30, and Tuesday, Dec 1, will attempt to power up the battery, and the third pass (4 hours), on Wednesday, Dec 2, will attempt to command on the transmitter. Time has been requested from the Arecibo and Green Bank observatories to listen during the Dec 2 pass. Week 50 (Dec 7-13) * Ahead starts the week at an SPE angle of 6.6 degrees, riding the HGA soft stop. * Ahead has 10 tracks during the week, and overall coverage is short 3.9 hours between Friday to Sunday, Dec 11-13. * A return-to-service track for station 34 is scheduled for Friday, Dec 11. There will be no instrument commanding or SSR playback during the track. * Behind starts the week at an SPE angle of 4.4 degrees. Recovery efforts for Behind are scheduled for Thursday-Saturday, Dec 10-12. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 44: M Oct 26 (299) T Oct 27 (300) W Oct 28 (301) T Oct 29 (302) F Oct 30 (303) S Oct 31 (304) S Nov 01 (305) Daylight savings time ends in U.S. Notes: * Ahead operating on the first side lobe, in IMPACT-prime mode. * No tracks for Behind due to superior solar conjunction. ------------------------------------------------------------------------------- Scheduled activities for Week 45: M Nov 02 (306) Ahead: Momentum dump, 17:30 UT T Nov 03 (307) W Nov 04 (308) T Nov 05 (309) F Nov 06 (310) S Nov 07 (311) S Nov 08 (312) Notes: * Ahead operating on the first side lobe, in SWAVES-prime mode. * No tracks for Behind due to superior solar conjunction. ------------------------------------------------------------------------------- Scheduled activities for Week 46: M Nov 09 (313) Ahead: Space weather beacon on NOAA stations resumes 21:55 UT T Nov 10 (314) Ahead: HGA on main lobe, offpoint 1 degree, 240 kbps Ahead: 30 kbps on 34 meter stations W Nov 11 (315) T Nov 12 (316) F Nov 13 (317) S Nov 14 (318) S Nov 15 (319) Ahead: No space weather broadcast following station 43 pass Notes: * Ahead starts the week on the first side lobe, in IMPACT-prime mode. The instruments will continue to produce telemetry at the first-side-lobe rates through the week, until the SSR partitions are reconfigured on Monday, Nov 16. * SECCHI will stop taking images near the end of the day on Nov 15 to assist in the SSR reconfigurations. Images will resume sometime on Nov 16 or 17. * No tracks for Behind due to superior solar conjunction. ------------------------------------------------------------------------------- Scheduled activities for Week 47: M Nov 16 (320) Ahead: HGA on main lobe, riding soft stop, 360 kbps Ahead: SSR playback and reconfiguration Ahead: No SECCHI telemetry 10:00-10:20 UT Ahead: Resume prime science real-time telemetry rates Ahead: End S/C telemetry in space weather broadcast T Nov 17 (321) Ahead: Instrument recommissioning, IMPACT SWEA/STE on W Nov 18 (322) T Nov 19 (323) Ahead: Uplink array test (DSS-25 & 26) F Nov 20 (324) S Nov 21 (325) Ahead: Return-to-service test with station 55 S Nov 22 (326) Notes: * After Friday, Nov 20, the Behind spacecraft will be able to operate on the first side lobe after it is recovered. * No tracks for Behind due to superior solar conjunction. ------------------------------------------------------------------------------- Scheduled activities for Week 48: M Nov 23 (327) Ahead: 96 kbps on 34 meter stations T Nov 24 (328) W Nov 25 (329) T Nov 26 (330) Thanksgiving F Nov 27 (331) S Nov 28 (332) S Nov 29 (333) Notes: * No tracks for Behind due to superior solar conjunction. ------------------------------------------------------------------------------- Scheduled activities for Week 49: M Nov 30 (334) Ahead: HGA on main lobe, riding soft stop, 480 kbps Ahead: 120 kbps on 34 meter stations Behind: Resume Behind recovery efforts T Dec 01 (335) W Dec 02 (336) Ahead: Begin No Gyro Operations (NGO) Ahead: First NGO momentum dump T Dec 03 (337) F Dec 04 (338) S Dec 05 (339) S Dec 06 (340) ------------------------------------------------------------------------------- Scheduled activities for Week 50: M Dec 07 (341) T Dec 08 (342) W Dec 09 (343) T Dec 10 (344) F Dec 11 (345) Ahead: Return-to-service track with station 34. S Dec 12 (346) S Dec 13 (347) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2015: * Dec 14 Ahead: 160 kbps on 34 meter stations * Dec 28 Ahead: Main lobe, riding soft stop, 720 kbps (70 m) * Dec 30 Ahead: HGA on main lobe 2016: * Jan 2 Behind: HGA on main lobe, offpoint 1 degree, 240 kbps Behind: Resume space weather broadcast to NOAA stations * Jan 5 Behind: HGA on main lobe, riding soft stop, 360 kbps Behind: SSR playback and reconfiguration * Jan 6 Behind: Instrument recommissioning, IMPACT SWEA/STE on * Jan 9 Behind: HGA on main lobe, riding soft stop, 480 kbps * Jan 11 Behind: HGA on main lobe, riding soft stop, 720 kbps * Jan 12 Ahead: First NGO SECCHI stepped calib. roll (date TBC) Behind: HGA on main lobe * Jan 27 Both: HGA calibration (NGO) * Mar 3 Behind: Resume LGA uplink capability on 70 m DSN * Apr 6 Ahead: Resume LGA uplink capability on 70 m DSN * May 16 Both: Post Solar Conjunction Assessment Review * Jul 5 Juno arrival at Jupiter * Dec Behind: Resume LGA downlink capability on 70 m DSN 2017: 2018: * Mar 5 Ahead: Mercury transit 2019: * Mar Ahead: Switch downlink rate to 240 kbps on 34 meter * Apr Behind: Switch downlink rate to 240 kbps on 34 meter 2020: * May Behind: Switch downlink rate to 360 kbps on 34 meter * Jun Ahead: Switch downlink rate to 360 kbps on 34 meter * Jun Behind: Switch downlink rate to 480 kbps on 34 meter * Sep Ahead: Switch downlink rate to 480 kbps on 34 meter 2021: * Jul Behind: Switch downlink rate to 720 kbps on 34 meter * Aug Ahead: Switch downlink rate to 720 kbps on 34 meter