STEREO Weekly Meeting Minutes for 2014-11-18 (Week 47) ANNOUNCEMENTS ------------- * Ahead operations on the first HGA antenna side lobe have been extended through Jan 4, 2015. * There will be no STEREO operations telecon on Dec 30. 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 46 (Nov 10-16) * On day 319 (Nov 15), during the DSS-14 support for Ahead, ranging lock was lost intermittently beginning at 1619z through 1756z. 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 #G115660 for more information. * On day 319 (Nov 15), during the DSS-43 support for Ahead, telemetry lock was lost intermittently between 2036z through 2138z due to heavy rain at the Canberra complex. This anomaly resulted in the loss of 192 frames of telemetry data. See DR #C110699 for more information. * On day 320 (Nov 16), during the DSS-14 support for Ahead, initial telemetry lock was delayed nine minutes beginning at 1510z due to a receiver anomaly at the station. A second receiver channel was added and telemetry lock occurred at 1519z. This anomaly resulted in the loss of 389 frames of telemetry data. See DR #G115663 for more information. * The Ahead observatory is operating on the first side lobe of the HGA to prevent overheating of the HGA feed assembly which is currently at 114 degrees C with the HGA angle at 7.9 degrees, with respect to the spacecraft-Sun line. * On day 315 (Nov 11), MOps macro release 1.1.26 and DHS release 1.1.10 were loaded to C&DH RAM. These releases contain macros and a RTDFD table to support instrument real-time science and spacecraft housekeeping telemetry using 34 meter stations while downlinking at 633 bps during side lobe operations. * On day 319 (Nov 15), during the DSS-43 support for Ahead, the spacecraft SSR playback was extended for the 4.75 hour duration of the support. This was necessary as the spacecraft SSR playback has fallen behind due to the number of Ahead tracks shifted to Behind for contingency operations. * On day 320 (Nov 16), during the DSS-35 CEC transmitter PIT support for Ahead, the macros and RTDFD table for real-time science telemetry along with spacecraft housekeeping telemetry at the 633 bps on a 34 meter station were tested. Telemetry rates for all instruments and spacecraft housekeeping were as planned and no unexpected data loss occurred. * The average daily science data return for Ahead, while operating on the first side lobe on the HGA, was 65 Mbits during this week. * 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 have been reduced to 3 hour 70 meter supports for 3 days in a row each week. * On days 315 through 317 (Nov 11-13), during the DSN 70 meter supports for Behind, recovery commanding 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. While the recovery and analysis efforts continue on Behind, as the Ahead observatory will enter superior solar conjunction in March, the primary focus of the engineering team is on developing operational configuration changes to add robustness to the G&C rate sensor usage to ensure the Ahead observatory’s continued safety. * 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 47 (Nov 17-23) * Macro release 1.1.25 was written to EEPROM on Ahead this morning (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 closed for the Thanksgiving holiday Thursday and Friday, Nov 27-28. * Starting Monday, Nov 24, the Ahead spacecraft will be switched over to the new spaceweather + spacecraft housekeeping mode after each track. * 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 next to 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 regularly scheduled 34 meter passes with this new 633 bps configuration. * 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) * 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 10 kbps on the first side lobe in IMPACT-prime mode, 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 10 kbps on the first side lobe in SWAVES-prime mode. * 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 10 kbps on the first side lobe in IMPACT-prime mode. * Behind has 3 passes during the week to attempt recovery, between Monday-Wednesday. Week 01 (Dec 29-Jan 4) * APL will be closed Jan 1-2 for the New Year holiday. * The HGA angle bias for the Ahead spacecraft will be updated on Jan 4 in prepartion for second-side lobe operations in the following week. * Ahead has 8 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 attemp recovery, between Tuesday-Thursday. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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) 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 first side lobe, in IMPACT-prime mode. ------------------------------------------------------------------------------- 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 first side lobe, in SWAVES-prime mode. ------------------------------------------------------------------------------- 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: * Ahead operating on first side lobe, in IMPACT-prime mode. ------------------------------------------------------------------------------- Scheduled activities for Week 01: M Dec 29 (363) T Dec 30 (364) W Dec 31 (365) T Jan 01 (001) New Year F Jan 02 (002) S Jan 03 (003) S Jan 04 (004) Ahead: Update HGA angle bias for second side lobe operations. Notes: * Ahead operating on first side lobe, in SWAVES-prime mode. ------------------------------------------------------------------------------- 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 Behind: Test with 34 meter at 633 bps, both side lobes 2015: * Jan 5 Ahead: HGA on 2nd side lobe * 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