STEREO Weekly Meeting Minutes for 2016-06-14 (Week 24) ANNOUNCEMENTS ------------- * None INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * There are currently no communications with the Behind spacecraft. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 23 (Jun 6-12) * On day 160 (Jun 8), during the DSS-25 support for Ahead, turbo decoder lock was lost briefly at 1625z and again at 1654z. This anomaly resulted in the loss of 2 frames of SSR data. Later in the support, the MOC/DSN command system aborted at 1808z. MOps reestablished the connection at 1835z. This anomaly had no impact on operations. * On day 161 (Jun 9), during the DSS-35 support for Ahead, a connection engine/automated link build issue at the Canberra complex resulted in an 83 minute late AOS at 0313z. SSR pointers were repositioned and all data were recovered on the subsequent support. This anomaly resulted in the loss of 1.4 hours of commanding, real-time telemetry, and two-way tracking data. See DR #C112124 for more information. * On day 161 (Jun 9), during the DSS-25 support for Ahead, turbo decoder lock was lost briefly at 2054z. This anomaly resulted in the loss of 1 frame of SSR data. * The Ahead observatory operated nominally during this week on the center of the HGA main lobe. The HGA feed assembly was at 90 degrees C and decreasing with the HGA angle at 11.9 degrees and increasing, with respect to the spacecraft-Sun line. * On day 160 (Jun 8), at 1600z, PLASTIC adjusted the accumulation times of heavy ion data products. Also, the s-channel switch was adjusted when transitioning from the main channel to the small channel to improve science data return. * On day 163 (Jun 11), the Ahead observatory was used to phase calibrate the 6th uplink array, using DSS-24, 25, and 26 for 1.9 hours, to support the array use for STEREO Behind battery recovery. An approximate 12 dB gain in uplink AGC was observed in the spacecraft transponder data. After the phasing calibration was completed, between 1700z to 1713z, the antennas were manually off-pointed to observe the effects of pointing errors on the uplink array. No SSR playback was conducted as the phasing of transmitters would have caused periodic dropped frames. * On day 164 (Jun 12), the Ahead observatory was used again to phase calibrate the 7th uplink array, using DSS-24, 25, and 26 for 1.9 hours, to support the array use for STEREO Behind battery recovery. An approximate 12 dB gain in uplink AGC was observed in the spacecraft transponder data. After the phasing calibration was completed, between 1700z to 1713z, the antennas were manually off-pointed to observe the effects of pointing errors on the uplink array. No SSR playback was conducted as the phasing of transmitters would have caused periodic dropped frames. * The average daily science data return for Ahead was 6.2 Gbits during this week. * On day 163 (Jun 11), the 6th uplink array for STEREO Behind recovery was conducted using DSS-24, 25, and 26. The uplink array was phase calibrated using the Ahead observatory first for 1.9 hours then the arrayed stations were switched to point to the Behind observatory. The configuration consisted of three 34m stations at the Goldstone complex using the 80 kW and two 20 kW transmitters incorporating the frequency segmented acquisition sequence with the MOC sending commands for battery recovery. Initial commanding was delayed five minutes due to the MOC being configured for DSS-24 vice DSS-26. This anomaly resulted in missing commanding for the first frequency segment. 315 commands covering 35 frequency segments were sent for battery state of charge recovery. * On day 164 (Jun 12), the 7th uplink array for STEREO Behind recovery was conducted using DSS-24, 25, and 26. The uplink array was phase calibrated using the Ahead observatory first for 1.9 hours then the arrayed stations were switched to point to the Behind observatory. The configuration consisted of three 34m stations at the Goldstone complex using the 80 kW and two 20 kW transmitters incorporating the frequency segmented acquisition sequence with the MOC sending commands for transmitter carrier recovery. 700 commands covering 35 frequency segments were sent. The DSN 70m station, DSS-14, monitored the downlink. JPL Radio Science also configured radio science receivers to aid in the signal detection. There were 6 occurrences where the DSS-14 declared lock, but correlating these lock times with the signal levels and high carrier residuals seem to indicate these may be false locks. JPL Radio Science also reported there were no indications of a spacecraft signal present in real-time, but a further in-depth look at the open loop data is being conducted. The Allen Telescope Array was not online during this carrier recovery attempt. * Starting in July, attempts to contact Behind will be reduced to once monthly, alternating months between phased uplink array passes, and single-dish passes which have a wider beam. This will continue through June 2017, after which recovery attempts will be suspended until January 2020, when the nominal uplink rate returns to 125 bps. The next uplink array attempt will be Jul 16-17. * The MOC will look into the question of what the expectations are for drift in the downlink frequency for Behind, particularly in regards to temperature. The recent false locks have been on the order of tens of kHz off the nominal frequency, while some expressed the opinion that the actual drift should be only a few kHz. Week 24 (Jun 13-19) * PLASTIC will be doing more real-time commanding during the station 26 pass on Thursday, Jun 16, to improve their data quality. * Bind testing between the MOC and ESA will be carried out on Thursday, Jun 16, to check out changes in the ESA network. Although these will only be tests of the ability to bind to the ESA antenna stations, they will be put into the schedule. * The STEREO Subsystem Assessment Review originally scheduled for tomorrow (Jun 15), has been rescheduled for Friday, Jun 24. * Ahead has 12 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, four at 360 kbps, five at 240 kbps, and one at 160 kbps. * Behind starts the week at an SPE angle of 15.1 degrees. There are no tracks for Behind during the week. Week 25 (Jun 20-26) * The STEREO Subsystem Assessment Review is scheduled for 9-11:30 AM EDT on Friday, Jun 24. Team members can call into the review using the same telephone number as that used for the weekly telecons. The MOC will also look into setting up a Webex connection. A package for the review will be sent out shortly. This review will cover the period between post solar conjunction and the end of April. * Ahead has 10 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, two at 360 kbps, four at 240 kbps, and two at 160 kbps. * Behind starts the week at an SPE angle of 15.2 degrees. Recovery efforts for Behind are Monday-Wednesday, Jun 20-22. The battery recovery tracks will be undertaken with the 80 kW transmitter on station 26. The Allen Telescope Array will listen for a signal Behind spacecraft, along with Arecibo for 1.3 hours. Week 26 (Jun 27-Jul 3) * The 5th battery discharge operation on Ahead is scheduled for Monday, Jun 27, for about 2 hours starting at 17:00. This will be performed during the support, and should not interfere with normal operations. The battery state of charge will be reduced to about 80-85% and assessed, and then reset back to full charge. * Ahead has 12 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, two at 360 kbps, four at 240 kbps, and three at 160 kbps. * Behind starts the week at an SPE angle of 15.2 degrees. There are no tracks for Behind. Week 27 (Jul 4-10) * Monday, July 4 is a holiday for APL. * Monday, July 4 is aphelion for Ahead. * The 89th momentum dump on Ahead is on Wednesday, Jul 6, at 16:00 UT. This will be the eighth momentum dump without using the gyros. * Ahead has 15 passes during the week, and overall coverage is nominal. There are four passes at 720 kbps, two at 360 kbps, five at 240 kbps, and four at 160 kbps. * Behind starts the week at an SPE angle of 15.1 degrees. There are no tracks for Behind during the week, since recovery attempts are now only once a month. Week 28 (Jul 11-17) * Ahead has 10 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, one at 360 kbps, four at 240 kbps, and two at 160 kbps. * Behind starts the week at an SPE angle of 15.1 degrees. * Uplink array attempts for Behind are scheduled for July 16, 17. The first 1.9 hours each day will use the Ahead spacecraft to calibrate the phasing between the stations. There will be no SSR playback or instrument commanding during these passes. Following the calibration, there will be a 3.3 hour pass for Behind on Jul 16 for battery recovery, and a 5.3 hour pass on Jul 17 for carrier recovery. The elevation will drop below 27.5 degrees for the last 48 minutes, so a waiver has been requested; otherwise, the station 26 power would need to be reduced from 80 to 60 kW. Station 14 will listen for the Behind carrier, along with the Allen Telescope Array. Week 29 (Jul 18-24) * The 35th SECCHI stepped calibration roll for Ahead is scheduled for Monday, Jul 18, starting at 13:00 UT. System momentum will be about 6 N-m-s. This is the aphelion roll, and the fourth without using the gyros. * A 3 hour project interface test with the new station 36 at Canberra is scheduled for Wednesday, Jul 20. The new station is expected to be operational sometime later this year. The downlink rate will be 160 kbps, and there will be no SSR playback or instrument commanding during the pass. * Ahead has 12 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, three at 360 kbps, five at 240 kbps, and one at 160 kbps. * Behind starts the week at an SPE angle of 15.0 degrees. There are no tracks for Behind during the week. Week 30 (Jul 25-31) * Ahead has 11 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, two at 360 kbps, and six at 240 kbps. * Behind starts the week at an SPE angle of 14.9 degrees. There are no tracks for Behind during the week. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 23: M Jun 06 (158) T Jun 07 (159) W Jun 08 (160) T Jun 09 (161) F Jun 10 (162) S Jun 11 (163) Behind: Phased array recovery attempt S Jun 12 (164) Behind: Phased array recovery attempt ------------------------------------------------------------------------------- Scheduled activities for Week 24: M Jun 13 (165) T Jun 14 (166) W Jun 15 (167) T Jun 16 (168) F Jun 17 (169) S Jun 18 (170) S Jun 19 (171) ------------------------------------------------------------------------------- Scheduled activities for Week 25: M Jun 20 (172) T Jun 21 (173) W Jun 22 (174) T Jun 23 (175) F Jun 24 (176) Ahead: STEREO Subsystem Assessment Review S Jun 25 (177) S Jun 26 (178) ------------------------------------------------------------------------------- Scheduled activities for Week 26: M Jun 27 (179) Ahead: Battery maintenance, 17:00 UT T Jun 28 (180) W Jun 29 (181) T Jun 30 (182) F Jul 01 (183) S Jul 02 (184) S Jul 03 (185) ------------------------------------------------------------------------------- Scheduled activities for Week 27: M Jul 04 (186) Independence Day Ahead: Aphelion T Jul 05 (187) Juno arrival at Jupiter W Jul 06 (188) Ahead: Momentum dump, 16:00 UT T Jul 07 (189) F Jul 08 (190) S Jul 09 (191) S Jul 10 (192) ------------------------------------------------------------------------------- Scheduled activities for Week 28: M Jul 11 (193) T Jul 12 (194) W Jul 13 (195) T Jul 14 (196) F Jul 15 (197) S Jul 16 (198) Behind: Phased array recovery attempt S Jul 17 (199) Behind: Phased array recovery attempt ------------------------------------------------------------------------------- Scheduled activities for Week 29: M Jul 18 (200) Ahead: SECCHI stepped calibration roll, 13:00 UT T Jul 19 (201) W Jul 20 (202) Ahead: Project interface test with station 36 T Jul 21 (203) F Jul 22 (204) S Jul 23 (205) S Jul 24 (206) ------------------------------------------------------------------------------- Scheduled activities for Week 30: M Jul 25 (207) T Jul 26 (208) W Jul 27 (209) T Jul 28 (210) F Jul 29 (211) S Jul 30 (212) S Jul 31 (213) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2016: * 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 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