STEREO Weekly Meeting Minutes for 2014-11-12 (Week 46) 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 45 (Nov 3-9) * On day 309 (Nov 5), the 73rd momentum dump was executed successfully at 2100z, which imparted a delta V of 0.097 m/sec. * The average daily science data return for Ahead, while operating on the first side lobe on the HGA, was 47 Mbits during this week. * On days 308 and 311 (Nov 4 and 7), during the DSN 70 meter supports, recovery commanding on Behind was conducted on 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. Operational configuration changes to add robustness to the G&C rate sensor usage for the Ahead observatory are being developed. * 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. * A question was raised as to which antenna would the spacecraft be on initially if it powered up from an unpowered state. The answer was that it would probably be the HGA. Week 46 (Nov 10-16) * A project interface test with the station 35 transmitter has been scheduled for Sunday, Nov 16, betwen 20-22 UT. * Yesterday (Nov 11), MOps macros 1.1.26 and data handling parameters 1.1.10 were written to RAM on Ahead. These are for use of the 34 meter stations with combined instrument space weather and spacecraft housekeeping data. These will be tested during the PIT test on Sunday. SECCHI will participate in this test. * 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. * Ahead has 9 passes during the week, all at 10 kbps on the first side lobe, in IMPACT-prime mode, in addition to the PIT test on Nov 16. * Behind has three 70 meter passes during the week to attempt recovery, between Tuesday-Thursday. Week 47 (Nov 17-23) * Macro release 1.1.25 will be written to EEPROM on Tuesday, Nov 18. * A 1.2 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 or SSR playback during the pass. * Ahead has 8 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 ready to begin using 34 meter stations to bring down spaceweather and housekeeping data. However, the DSN schedule is already negotiated out through January. 34 meter passes will be addded as they come available. * The MOC will be closed for the Thanksgiving holiday Thursday and Friday, Nov 27-28. * The Hayabusa 2 mission launch window opens on Sunday, Nov 30, and continues for 6 days. The only effect on the STEREO DSN schedules is that some passes may be shortened if it's launched on the last day in the window. * 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) * MOps macros 1.1.26 and data handling parameters 1.1.10 will be loaded to EEPROM on Monday, Dec 1, during the station 63 pass. * Space weather and housekeeping beacon data will be brought down during an ESA New Norcia pass on Dec 2, and during a station 55 pass on Thursday, Dec 4. These will be the first 34 meter passes with this new 633 bps configuration. * 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. * There was some discussion whether this switch could be made contingent on temperature, and postponed again. This decision would need to be made with sufficient time to accommodate the planning. * Ahead has 11 passes during the week, nine at 10 kbps on the first side lobe, in SWAVES-prime mode, and two at the 633 bps beacon rate. * 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. * The 74th momentum dump on Ahead is scheduled for Tuesday, Dec 9, with ignition at 20:30 UT. * Ahead has 10 passes during the week, eight at 3 kbps on the second side lobe, and two at the 633 bps beacon rate on Wednesday and Friday. * Behind has 3 passes during the week to attempt recovery, between Monday-Wednesday. Week 51 (Dec 15-21) * A return-to-service track for station 14 is scheduled for Monday, Dec 15. There will be no instrument commanding or SSR playback during this track. * Ahead has 7 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. Week 52 (Dec 22-28) * Thursday, Dec 25, is Christmas. APL will be closed Dec 25-26 for the holiday. * 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. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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, test of space weather 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) Ahead: Momentum dump, 20:30 UT 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) Ahead: Return-to-service track for D14 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. ------------------------------------------------------------------------------- Scheduled activities for Week 52: M Dec 22 (356) T Dec 23 (357) W Dec 24 (358) T Dec 25 (359) Christmas F Dec 26 (360) S Dec 27 (361) S Dec 28 (362) Notes: * Other activities for Week 52: * ------------------------------------------------------------------------------- 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