STEREO Weekly Meeting Minutes for 2017-08-08 (Week 32) ANNOUNCEMENTS ------------- * The Behind recovery readiness review has been rescheduled for Tuesday, August 29, 9 AM at APL. A webex announcement has been sent out. If planning to come to APL for the review, please inform Dan Ossing. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * Attempts to recover Behind have transitioned from monthly schedule to a weekly schedule (every 3-days). DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 31 (Jul 31-Aug 6) * On day 215 (Aug 3), during the DSS-36 support for Ahead, turbo decoder lock was lost intermittently at 0639z through 0655z due to heavy rain at the Canberra complex. This anomaly resulted in the loss of 2431 frames of real-time telemetry and SSR data. See DR #C112842 for more information. * On day 212 (Jul 31), the 101st momentum dump on Ahead was executed successfully at 1730z, which imparted an estimated delta V of 0.090 m/sec. This was the 20th momentum dump that did not use the IMU. After thruster operations complete, there was a 0.15 degree of roll angle error which was dampened out over the next 8.2 minutes. Fine pointing stabilized 2.0 minutes after completion of the momentum dump. * The average daily science data return for Ahead was 5.9 Gbits during this week. * On day 212 (Jul 31), during a 4 hour support for Behind with DSS-63, the command monitor data was lost from 0713z through 0731z due to an interface assembly application problem. This anomaly resulted in the loss of one segment of commanding. A total of 400 commands were transmitted during the support. No carrier was detected by either the DSN station or the radio science receiver team after attempting to power on the TWTA for 30 minutes. Transitioned to battery recovery operations for the remainder of the support which consists of repeatedly sweeping a 4 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. See DR #N110669 for more information. * On day 216 (Aug 4), during a 4 hour support for Behind with DSS-63, 420 commands were transmitted during the support. No carrier was detected by either the DSN station or the radio science receiver team after attempting to power on the TWTA for 30 minutes. Transitioned to battery recovery operations for the remainder of the support which consists of repeatedly sweeping a 4 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. * On day 218 (Aug 6), during a 4 hour support for Behind with DSS-63, 420 commands were transmitted during the support. No carrier was detected by either the DSN station or the radio science receiver team after attempting to power on the TWTA for 30 minutes. Transitioned to battery recovery operations for the remainder of the support which consists of repeatedly sweeping a 4 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. Week 32 (Aug 7-13) * Yesterday (Aug 7), during a 3.5 hour support for Behind with station 63, 380 comands were sent to the spacecraft. No carrier was detected. * Ahead has 9 tracks during the week, and overall coverage is nominal. There are eight tracks at 720 kbps, and one at 160 kbps. The station 63 support on Thursday has been shortened by one hour. * Recovery tracks for Behind are scheduled for Monday (DSS-63), Wednesday (DSS-43), and Saturday (DSS-14), Aug 7, 9, 12. The Radio Science Receiver will be operating during all tracks. Week 33 (Aug 14-20) * On Day 130 (Aug 18) there will be a return to service support demonstration track with Station DSS-24 for 2.6 hours. No SSR playback nor instrument commanding, and downlinking at 160 kbits/sec. * TDRS is scheduled for launch on Aug 18, with a 40 minute window each day. * Ahead has 7 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, and one at 240 kbps. * Recovery tracks for Behind are scheduled for Monday, Wednesday, and Friday, Aug 14, 16, 18 (about 3.5 hours each). The Radio Science Receiver will be operating during all tracks. Week 34 (Aug 21-27) * A total solar eclipse will be seen across the United States on Monday, Aug 21. SECCHI will be taking extra coronagraph images during the eclipse. There is a total of 5 hours of 70 meter downlink the next day, which should empty the recorder. * Ahead has 9 tracks during the week, and overall coverage is nominal. There are eight tracks at 720 kbps, and one at 240 kbps. * Recovery tracks switch to a daily cadence (~4-hours 70-m time each day). During the first two days, will use a different frequency acquisition sequence (using 1 kHz steps and going down 18 steps and then back up) in case the transponder has drifted out of the currently used 4kHz range. Anticipate using this finer frequency resolution the first two days of each week, with the first track being for battery recovery, and the second track being for carrier recovery. Recovery tracks for Behind are scheduled (each about 3.5-4 hours of 70-m support) for Monday, Wednesday, and Friday, Aug 21, 23, 25. The Radio Science Receiver will be operating during all tracks. Week 35 (Aug 28-Sep 3) * The 40th SECCHI stepped calibration roll on Ahead is scheduled for Tuesday, Aug 29, starting at 11:55 UT. This is for the midpoint in the orbit. System momentum is expected to be 6 N-m-s. This will be the 9th stepped roll without using the gyros. * Ahead has 8 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, and two at 240 kbps. * Recovery tracks for Behind are scheduled each day, with the older frequency acquisition sequence with the finer 1 kHz steps used on Monday and Tuesday, with the first track being for battery recovery, and the second track being for carrier recovery. Week 36 (Sep 4-10) * Monday, Sep 4, is Labor Day, which is an APL holiday. * The 102nd momentum dump on Ahead is scheduled for Wednesday, Sep 6, with ignition at 17:30 UT. This will be the 21st momentum dump without using the gyros. * Ahead has 10 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, two at 240 kbps, and one at 160 kbps. * Recovery tracks for Behind are scheduled each day, with the older frequency acquisition sequence with the finer 1 kHz steps used on Tuesday and Wednesday, with the first track being for battery recovery, and the second track being for carrier recovery. Week 37 (Sep 11-17) * Ahead has 11 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, three at 240 kbps, and one at 160 kbps. * Recovery tracks for Behind are scheduled every day, with the older frequency acquisition sequence with the finer 1 kHz steps used on Thursday and Friday, with the first track being for battery recovery, and the second for carrier recovery. Week 38 (Sep 18-24) * Ahead has 8 tracks during the week, all at 720 kbps, and overall coverage is nominal. * Recovery tracks for Behind are scheduled every day, with the older frequency acquisition sequence with the finer 1 kHz steps using on Monday and Tuesday, with the first track being for battery recovery, and the second for carrier recovery. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 32: M Aug 07 (219) Behind: Recovery track with station 63 T Aug 08 (220) W Aug 09 (221) Behind: Recovery track with station 43 T Aug 10 (222) F Aug 11 (223) S Aug 12 (224) Behind: Recovery track with station 14 S Aug 13 (225) ------------------------------------------------------------------------------- Scheduled activities for Week 33: M Aug 14 (226) Behind: Recovery track with station 14 T Aug 15 (227) W Aug 16 (228) Behind: Recovery track with station 43 T Aug 17 (229) F Aug 18 (230) Ahead: Return-to-service track with station 24 Behind: Recovery track with station 43 S Aug 19 (231) S Aug 20 (232) ------------------------------------------------------------------------------- Scheduled activities for Week 34: M Aug 21 (233) Begin daily Behind recovery tracks Solar eclipse in the United States T Aug 22 (234) W Aug 23 (235) T Aug 24 (236) F Aug 25 (237) S Aug 26 (238) S Aug 27 (239) Note: * The first two Behind recovery passes use the original frequency acquisition sequence with the finer 1 kHz resolution. The first pass is for battery recovery, and the second is for carrier recovery. * Extra SECCHI coronagraph images during the eclipse. ------------------------------------------------------------------------------- Scheduled activities for Week 35: M Aug 28 (240) T Aug 29 (241) Ahead: SECCHI stepped calibration roll, 11:55 UT W Aug 30 (242) T Aug 31 (243) F Sep 01 (244) S Sep 02 (245) S Sep 03 (246) Notes: * Behind recovery attempts each day. The first two Behind recovery passes use the original frequency acquisition sequence with the finer 1 kHz resolution. The first pass is for battery recovery, and the second is for carrier recovery. ------------------------------------------------------------------------------- Scheduled activities for Week 36: M Sep 04 (247) Labor Day T Sep 05 (248) W Sep 06 (249) Ahead: Momentum dump, 17:30 UT T Sep 07 (250) F Sep 08 (251) S Sep 09 (252) S Sep 10 (253) Notes: * Behind recovery attempts each day. The Tuesday and and Wednesday Behind recovery passes use the original frequency acquisition sequence with the finer 1 kHz resolution. The first pass is for battery recovery, and the second is for carrier recovery. ------------------------------------------------------------------------------- Scheduled activities for Week 37: M Sep 11 (254) T Sep 12 (255) W Sep 13 (256) T Sep 14 (257) F Sep 15 (258) S Sep 16 (259) S Sep 17 (260) Notes: * Behind recovery attempts each day. The Thursday and and Friday Behind recovery passes use the original frequency acquisition sequence with the finer 1 kHz resolution. The first pass is for battery recovery, and the second is for carrier recovery. ------------------------------------------------------------------------------- Scheduled activities for Week 38: M Sep 18 (261) T Sep 19 (262) W Sep 20 (263) T Sep 21 (264) F Sep 22 (265) S Sep 23 (266) S Sep 24 (267) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 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 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