STEREO Weekly Meeting Minutes for 2014-11-05 (Week 45) ANNOUNCEMENTS ------------- * None. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating on the first side lobe of the HGA to prevent overheating of the feed assembly. * There are currently no communications with the Behind spacecraft. See below for details. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 44 (Oct 27-Nov 2) * On day 302 (Oct 29), no real-time science telemetry was downlinked from Ahead as the scheduled 70 meter support with DSS-14 was changed to a 34 meter support with DSS-35 in support of the STEREO Behind communication recovery. Also, command uplink was two hours late and was resolved after the station reset CMG. See DR #C110674 for more information. * On day 304 (Oct 31), no real-time science telemetry was downlinked from Ahead as the scheduled 70 meter support with DSS-43 was changed to a 34 meter support with DSS-55 in support of the STEREO Behind communication recovery. * The average daily science data return for Ahead, while operating on the first side lobe on the HGA, was 40 Mbits during this week. * On day 301, during the DSS-43 support, communications with the antenna interface were lost for eight minutes beginning at 2241z. See DR #C110672 for more information. * Detailed status of the activities that occurred on the Behind loss of communication anomaly, which occurred on day 274 (Oct 1), are listed below. To ensure communications on the LGA during long term recovery efforts, the Behind track coverage will be reduced to 3 hour 70 meter supports for 3 days in a row each week commencing in week 46, on November 10th. * On days 300 through 301 (Oct 27-28), during the DSN 70 meter support for Behind each day, contingency commanding continued with ensuring that IMU-A is disabled as it has failed. No signal was received by the DSN radio science receivers. * On days 302 through 306 (Oct 29-Nov 2), during the DSN 70 meter supports for Behind, recovery commanding was switched back to ensuring that the transmitter is in its operational configuration. No signal was received by the DSN radio science receivers. * Significant findings to date: 1. Analysis of the three DSN extracted telemetry frames from the carrier signal just before the planned observatory reset/anomaly occurred on day 274, October 1st, showed nominal performance of the spacecraft, i.e., no anomalies, IMU off, and the star tracker providing an attitude solution. 2. Post reset, from the very limited telemetry, three packets, extracted from the carrier signal by the DSN, the X-axis gyro on IMU-A had failed. Unfortunately, this telemetry contained only G&C anomaly data and no spacecraft summary data, i.e., the state of the RF, G&C, fault protection and other subsystems is not known at the time of the anomaly. With a failed IMU and the star tracker being off-line for an undetermined duration, the sun sensors will keep the observatory pointed at the Sun, though the G&C will not have any roll knowledge, and cannot roll the observatory as part of the safing configuration to re-establish communications on the LGAs. From analysis of this telemetry and initial G&C simulations, it is highly suspected that the observatory is rotating about the principal access of inertia due to an autonomous momentum dump initiated by bad gyro data flagged good, but this has not yet been confirmed. 3. At least two anomalies occurred post reset, the star tracker not promoting to AAD mode and the X-axis gyro failure. Unfortunately, due to the number of possible combinations, the STEREO fault protection system is not designed for simultaneous failures. * The cause and effect analysis of the loss of communications from the LGAs is continuing. G&C simulations using the bad gyro data flagged good are continuing to better understand the potential impact to the observatory state. Recovery from a negative power state is also being investigated. * Once communications are restored and the anomaly resolved, the operational plan for exiting the solar conjunction testing will continue to return the Behind observatory back to nominal science data collection as soon as safely possible. Week 45 (Nov 3-9) * The 73rd momentum dump on Ahead will be carried out on Nov 5, starting at 21:00 UT. * Ahead has 7 passes during the week, all at 10 kbps on the first side lobe, in SWAVES-prime mode. It has been confirmed that SWAVE-prime data is being downlinked as expected. * Behind has two 70 meter passes during the week to attempt recovery, on Tuesday and Friday. Week 46 (Nov 10-16) * The DSN schedules have been reworked to reallocate some of the 70 meter passes for Behind to Ahead, leaving three 70 meter passes of 3 hours duration each during the week for Behind recovery operations. * The station 43 pass for Ahead near the end of the day on day 319 (Nov 15) will contain a spacecraft SSR playback for the entire duration. This is necessary as the spacecraft SSR playback has fallen behind due to the number of AHEAD tracks shifted to BEHIND for contingency operations. The MOC has requested that SECCHI not produce any telemetry during this period. There is another 3 hour pass just prior to this pass. * A project interface test with the station 35 transmitter has been scheduled for Sunday, Nov 16, betwen 20-22 UT. * Ahead has 10 passes during the week, all at 10 kbps on the first side lobe, in IMPACT-prime mode. * Behind has three 70 meter passes during the week to attempt recovery, between Tuesday-Thursday. Week 47 (Nov 17-23) * The MOC plans to start using 34 meter stations with Ahead to bring down space weather beacon data. However, these passes have not yet been scheduled. * The SECCHI team discussed their need to do commanding during the 34 meter tracks to throttle back their beacon telemetry rate to allow room for spacecraft housekeeping data. These commands cannot be stored within their own scheduling software. There was some discussion whether the commands need to be sent in realtime or whether the spacecraft stored command buffer can be used. Another option is to send the commands at the end of the previous pass. The POC queues can be kept open longer for this purpose. * A 1.7 hour return-to-service track for station 63 is scheduled for day 327 (Nov 23). This pass was originally scheduled for Behind, but has been rescheduled for Ahead. There will be no instrument commanding during the pass. * Ahead has 11 passes during the week, all at 10 kbps on the first side lobe, in SWAVES-prime mode. * Behind has three 70 meter passes during the week to attempt recovery, between Monday-Wednesday. Week 48 (Nov 24-30) * The MOC will be closed for the Thanksgiving holiday Thursday and Friday, Nov 27-28. * Ahead has 11 passes during the week, all at 10 kbps on the first side lobe, in IMPACT-prime mode. * Behind has three 70 passes during the week to attempt recovery, between Friday-Sunday. Week 49 (Dec 1-7) * The HGA angle bias for the Ahead spacecraft will be updated on Dec 7 in prepartion for second-side lobe operations in the following week. * If the HGA temperatures on Ahead continue to perform as expected, the switch to second side lobe operations may be further postponed. * Ahead has 9 passes during the week, all at 10 kbps on the first side lobe, in SWAVES-prime mode. * Behind has 3 passes during the week to attempt recovery, between Tuesday-Thursday. Week 50 (Dec 8-14) * Ahead commences operations on the second side lobe on Monday, Dec 8. * Ahead has 10 passes during the week, all at 3 kbps on the second side lobe. * Behind has 3 passes during the week to attempt recovery, between Monday-Wednesday. Week 51 (Dec 15-21) * Ahead has 10 passes during the week, all at 3 kbps on the second side lobe. * Behind has 3 passes during the week to attempt recovery, between Wednesday-Friday. Other * The SSC asked whether the Ahead spacecraft still transmitted space weather beacon telemetry between DSN track. This question in response to a desire on the part of South Korean space weather agency to test their new antenna site in Jeju. The MOC responded that the spacecraft transmits at the same 633 bps rate, but all the packets are spacecraft housekeeping. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 45: M Nov 03 (307) T Nov 04 (308) W Nov 05 (309) Ahead: Momentum dump, 21:00 UT T Nov 06 (310) F Nov 07 (311) S Nov 08 (312) S Nov 09 (313) Notes: * Emergency DSN contacts for Behind requested through Nov 9. * Ahead operating on first side lobe, in SWAVES-prime mode. ------------------------------------------------------------------------------- Scheduled activities for Week 46: M Nov 10 (314) T Nov 11 (315) W Nov 12 (316) T Nov 13 (317) F Nov 14 (318) S Nov 15 (319) S Nov 16 (320) Ahead: PIT test with D35, 20-22 UT Notes: * Ahead operating on first side lobe, in IMPACT-prime mode. ------------------------------------------------------------------------------- Scheduled activities for Week 47: M Nov 17 (321) T Nov 18 (322) W Nov 19 (323) T Nov 20 (324) F Nov 21 (325) S Nov 22 (326) S Nov 23 (327) Ahead: Return-to-service track with D63. Notes: * Ahead operating on first side lobe, in SWAVES-prime mode. ------------------------------------------------------------------------------- Scheduled activities for Week 48: M Nov 24 (328) T Nov 25 (329) W Nov 26 (330) T Nov 27 (331) Thanksgiving F Nov 28 (332) S Nov 29 (333) S Nov 30 (334) Notes: * Ahead operating on first side lobe, in IMPACT-prime mode. ------------------------------------------------------------------------------- Scheduled activities for Week 49: M Dec 01 (335) T Dec 02 (336) W Dec 03 (337) T Dec 04 (338) F Dec 05 (339) S Dec 06 (340) S Dec 07 (341) Ahead: Update HGA angle bias for second side lobe operations. Notes: * Ahead operating on first side lobe, in SWAVES-prime mode. ------------------------------------------------------------------------------- Scheduled activities for Week 50: M Dec 08 (342) Ahead: Start of second side-lobe operations T Dec 09 (343) W Dec 10 (344) T Dec 11 (345) F Dec 12 (346) S Dec 13 (347) S Dec 14 (348) Notes: * Ahead operating on second side lobe. ------------------------------------------------------------------------------- Scheduled activities for Week 51: M Dec 15 (349) T Dec 16 (350) W Dec 17 (351) T Dec 18 (352) F Dec 19 (353) S Dec 20 (354) S Dec 21 (355) Notes: * Ahead operating on second side lobe. ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2014: * Nov 19 Behind: HGA hits soft stop * Nov 28 Behind: SSR reconfiguration * Dec 1 Behind: HGA on 1st side lobe * Dec 8 Ahead: HGA on 2nd side lobe * Dec 8 Behind: Test with 34 meter at 633 bps, both side lobes 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