STEREO Weekly Meeting Minutes for 2018-09-04 (Week 36) ANNOUNCEMENTS ------------- * None INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * Behind has transitioned to a monthly schedule to attempt to recover the spacecraft. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 35 (Aug 27-Sep 2) * On day 240, Tuesday August 28th, during the DSS-34 support, turbo decoder lock was lost briefly at 02:58 UT. This anomaly resulted in the loss of 3 frames of SSR data. * On day 242, Thursday August 30th, during the DSS-43 support, turbo decoder lock was lost intermittently at 22:56 UT through 23:45 UT due to rain at the Canberra complex. These anomalies resulted in the loss of 14,989 frames of real-time telemetry and SSR data. See DR# C113633 for more information. * On day 244, Saturday September 1st, before BOT at 0945z for the DSS-54 support, the transmitter was declared red due to a generator issue. This anomaly resulted in the loss of 4 hours of commanding and two-way tracking data. All SSR data was received. See DR# M110791 for more information. * The Ahead observatory operated nominally during this week. * On day 241, August 29th the 112th momentum dump was executed successfully at 14:30 UT, which imparted an estimated delta V of 0.086 m/sec. This was the 31st momentum dump that did not use the IMU. After thruster operations completed, there was a 0.44 degree of roll angle error. However, fine pointing was not stabilized until 21 hours after completion of the momentum dump. Post momentum dump, the wheel speed avoidance algorithm set a target of zero rad/sec for reaction wheel #4 which resulted in intermittent loss of fine pointing lock from day 241, August 29th 14:33 UT through 11:34 UT the next day. While the algorithm is supposed to keep all reaction wheels away from zero and outside ± 30.79 rad/sec, it is not known at this time why wheel 4 was allowed to operate so close to zero for so long. Day 242, August 30th, 11:34, wheel #4 autonomously moved away from zero and eventually settled at ~ -80 rad/sec when all four wheels re-distributed momentum. Simulations are being conducted to analyze the issue and determine possible options. This is the 2nd time this occurred on the Ahead observatory during the 12 years on orbit. * The average daily science data return for Ahead was 5.6 Gbits during this week. * There were no recovery passes for Behind during the week. Week 36 (Sep 3-9) * The DSN network will be down for maintenance between 11-15 UT on Wednesday, Sep 5. This will have no effect on STEREO operations. * Ahead has 13 tracks during the week, and overall coverage is now nominal with the addition of two ESA Malargue passes on Wednesday and Friday. There are six tracks at 720 kbps, one at 360 kbps, four at 240 kbps, and two at 160 kbps. * There are no recovery passes for Behind during the week. Week 37 (Sep 10-16) * There are ten tracks for Ahead during the week, and overall coverage is now nominal with the addition of ESA Malargue tracks on Wednesday and Thursday. There are three tracks at 720 kbps, two at 360 kbps, one at 240 kbps, and four at 160 kbps. * There are no recovery passes for Behind during the week. Week 38 (Sep 17-23) * There will be a telemetry assessment review on Wednesday, Sep 19, from 9-12 AM, 13:00-16:00 UT at APL. Webex invitations have been sent out. Please let APL know ahead of time if you plan to attend in person, so that security passes can be obtained. * Ahead has eight passes during the week, and overall coverage is nominal. There are five passes at 720 kbps, two at 240 kbps, and one at 160 kbps. * Recovery passes for Behind using the 1 kHz frequency acquisition sequence are scheduled for Friday, Sep 21 (battery), and on Saturday and Sunday, Sep 22, 23 (both carrier). Week 39 (Sep 24-30) * Ahead has nine passes during the week, and overall coverage is now nominal with the addition of an ESA New Norcia pass on Monday, and an ESA Cebreros pass on Thursday. There are six passes at 720 kbps, one pass at 360 kbps, and two passes at 160 kbps. * There are no recovery passes for Behind during the week. Week 40 (Oct 1-7) * On Tuesday, October 2nd, the 113th momentum dump is scheduled for 15:30 UT. This will be the 32nd momentum dump that does not use the gyros. * Ahead has eleven passes during the week, and overall coverage is nominal. There are six passes at 720 kbps, two at 360 kbps, and three at 160 kbps. This includes 4.25 hours of ESA New Norcia coverage on Tuesday and the momentum dump on ESA Malargue on Tuesday for 4.25 hours. * Wednesday October 3rd, test track on ESA Malargue for 4 hours to test the Ahead MOC transition to CCSDS SLE bluebook version 4. * There are no recovery passes for Behind during the week. Week 41 (Oct 8-14) * Ahead has eleven passes during the week, and overall coverage is nominal. There are six passes at 720 kbps, two at 360 kbps, one at 240 kbps, and two at 160 kbps. This includes ESA Cebreros passes on Monday and Thursday. * There are no recovery passes for Behind during the week. * October 10th, Behind MOC testing the SLE bluebook version 4 between MOC and ESA Cebreros. * Oct 12th Behind reaches perihelion. Week 42 (Oct 15-Oct 21) *Ahead seven tracks scheduled, short 8 hours of time Thursday through Saturday 291-293. Have requested ESA support for those 8 hours. Four passes scheduled for 720 kbps, two at 360 kbps and one at 160 kbps. * Search pattern recovery passes for Behind are scheduled for Monday October 15th (battery), and on Tuesday and Wednesday, October 16th and 17th (both carrier). COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 36: M Sep 03 (246) Labor Day T Sep 04 (247) W Sep 05 (248) T Sep 06 (249) F Sep 07 (250) S Sep 08 (251) S Sep 09 (252) ------------------------------------------------------------------------------- Scheduled activities for Week 37: M Sep 10 (253) T Sep 11 (254) W Sep 12 (255) T Sep 13 (256) F Sep 14 (257) S Sep 15 (258) S Sep 16 (259) ------------------------------------------------------------------------------- Scheduled activities for Week 38: M Sep 17 (260) T Sep 18 (261) W Sep 19 (262) T Sep 20 (263) F Sep 21 (264) Behind: Recovery track, DSN 14 (1 kHz, battery) S Sep 22 (265) Behind: Recovery track, DSN 14 (1 kHz, carrier) S Sep 23 (266) Behind: Recovery track, DSN 14 (1 kHz, carrier) ------------------------------------------------------------------------------- Scheduled activities for Week 39: M Sep 24 (267) T Sep 25 (268) W Sep 26 (269) T Sep 27 (270) F Sep 28 (271) S Sep 29 (272) S Sep 30 (273) ------------------------------------------------------------------------------- Scheduled activities for Week 40: M Oct 01 (274) T Oct 02 (275) Ahead: Momentum dump, 15:30 UT W Oct 03 (276) T Oct 04 (277) F Oct 05 (278) S Oct 06 (279) S Oct 07 (280) ------------------------------------------------------------------------------- Scheduled activities for Week 41: M Oct 08 (281) T Oct 09 (282) W Oct 10 (283) T Oct 11 (284) F Oct 12 (285) S Oct 13 (286) S Oct 14 (287) ------------------------------------------------------------------------------- Scheduled activities for Week 42: M Oct 15 (288) Behind: Recovery track, DSN 14 (search pattern, battery) T Oct 16 (289) Behind: Recovery track, DSN 43 (search pattern, carrier) W Oct 17 (290) Behind: Recovery track, DSN 43 (search pattern, carrier) T Oct 18 (291) F Oct 19 (292) S Oct 20 (293) S Oct 21 (294) Upcoming events: Behind events are contingent on recovering the spacecraft. 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 2022: 2023: * May 5 Behind: Mercury transit * Jul 17 Behind: Closest approach to Earth * Aug 13 Ahead: Closest approach to Earth 2024: 2025: * Apr 7 Ahead: Mercury transit 2026: 2027: * Feb 1 Behind: Mercury transit 2028: 2029: * Jun 30 Ahead: Mercury transit