STEREO Weekly Meeting Minutes for 2018-05-01 (Week 18) ANNOUNCEMENTS ------------- * Because of a problem with a filled disk partition, some files produced today (May 1) incorrectly show zero file size. This includes telemetry files, attitude history files, and some other data products. This problem should be corrected shortly. 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 17 (Apr 23-29) * On day 115 (Apr 25), during the DSS-55 support for Ahead, turbo decoder lock was lost intermittently at 1539z through 1555z due to rain at the Madrid complex. The SSR pointers were repositioned to minimize data loss. This anomaly resulted in the loss of 22,131 frames of real-time telemetry and SSR data. However, all SSR data were recovered. See DR# M110566 for more information. * On day 117 (Apr 27), during the DSS-43 support for Ahead, turbo decoder lock was lost briefly at 0603z. This anomaly resulted in the loss of 1 frame of SSR data. * On day 118 (Apr 28), during the DSS-14 support for Ahead, turbo decoder lock was lost intermittently from 2037z through 2045z, then telemetry lock was lost at 2059z through 2223z, all due a sub-reflector issue at the station. This anomaly resulted in the loss of 1.5 hours of commanding, tracking, real-time telemetry, and SSR data. See DRs #G119083 and G119084 for more information. * On day 119 (Apr 29), during the DSS-35 support for Ahead, telemetry lock was lost at 0440z through 0502z followed by intermittent loss of turbo decoder lock through 0533z due to heavy rain at the Canberra complex. This anomaly resulted in the loss of 24 minutes of commanding, tracking, real-time telemetry, and SSR data. See DR# C113406 for more information. * On day 119 (Apr 29), the star tracker on Ahead failed to find a solution at 15:20:46z. Fault protection soft reset the star tracker and promoted it back to AAD mode 15:24:01z. Diagnostic data indicated the reset cause was due to a CPU Error, which has occurred previously. With no X-axis rate data available to G&C, a 1.2 degree X-axis roll error occurred which resulted in the loss of fine pointing for a total of 6.2 minutes, from 15:22:05z through 15:28:16z. This was the 7th star tracker reset on the Ahead observatory since launch. * The average daily science data return for Ahead was at least 6.2 Gbits during this week. The total may increase when the updated telemetry files are available, following the resolution of the filled disk partition mentioned earlier. Week 18 (Apr 30-May 6) * The COR2 deep exposure campaign ended yesterday, Apr 30. * The NASA InSight launch is scheduled for Saturday, May 5, between 11:05-13:05 UT. Contingency plans have been made for the next four days following the planned launch date. Minor effects on the STEREO schedule will occur if the launch slips to the following Monday. * Ahead has 13 passes during the week, and overall coverage is nominal. There are five passes at 720 kbps, two at 360 kbps, and six at 240 kbps. * There are no recovery passes scheduled for Behind during the week. Week 19 (May 7-13) * The 7th battery discharge maintenance event is scheduled for Monday, May 7, starting at 12:00 UT. This procedure is carried out annually, around the time of aphelion, and will be done during a track. The battery charge state is reduced to about 85% and then restored. This does not affect instrument operations. Autonomy rules are used to make sure that the battery returns to a properly charged state. * The 43rd SECCHI stepped calibration roll is scheduled for Tuesday, May 8, starting at 10:30 UT. This will be the 12th stepped roll without using the gyros. This is the aphelion roll; the actual aphelion is May 24. System momentum is expected to be about 5 N-m-s. * Ahead has 13 passes during the week, and overall coverage is nominal. There are six passes at 720 kbps, and six at 240 kbps, and one at 160 kbps. A previously scheduled pass at 360 kbps has been removed to avoid any potential problems with the contingency plans for the InSight mission. * There are no recovery passes scheduled for Behind during the week. Week 20 (May 14-20) * The 109th momentum dump on Ahead is scheduled for Tuesday, May 15, starting at 20:00 UT. This will be the 28th momentum dump without using the gyros. * Ahead has 13 passes during the week, and overall coverage is nominal. There are eight passes at 720 kbps, four at 240 kbps, and one at 160 kbps. * 1 kHz frequency acquisition recovery tracks for Behind are scheduled for Friday, May 18 (battery), and on Saturday, May 19, and Sunday, May 20 (both carrier). Week 21 (May 21-27) * Ahead reaches aphelion on Thursday, May 24. * Ahead has 12 passes during the week, and overall coverage is nominal. There are nine passes at 720 kbps, two at 360 kbps, and one at 240 kbps. * There are no recovery passes for Behind scheduled during the week. Week 22 (May 28-Jun 3) * Monday, May 28, is Memorial Day, which is an APL holiday. * Ahead has 13 passes during the week, and overall coverage is nominal. There are six passes at 720 kbps, three at 360 kbps, two at 240 kbps, and two at 160 kbps. * There are no recovery passes for Behind scheduled during the week. Week 23 (Jun 4-10) * Ahead has 12 passes during the week, and overall coverage is nominal. There are six passes at 720 kbps, four at 360 kbps, one at 240 kbps, and one at 160 kbps. * There are no recovery passes for Behind scheduled during the week. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 18: M Apr 30 (120) Ahead: SECCHI/COR2 deep exposure campaign T May 01 (121) W May 02 (122) T May 03 (123) F May 04 (124) S May 05 (125) S May 06 (126) ------------------------------------------------------------------------------- Scheduled activities for Week 19: M May 07 (127) Ahead: Battery maintenance, 12 UT T May 08 (128) Ahead: SECCHI stepped calibration roll, 10:30 UT W May 09 (129) T May 10 (130) F May 11 (131) S May 12 (132) S May 13 (133) ------------------------------------------------------------------------------- Scheduled activities for Week 20: M May 14 (134) T May 15 (135) Ahead: Momentum dump, 20 UT W May 16 (136) T May 17 (137) F May 18 (138) Behind: Recovery track, DSN 14 (1 kHz, battery) S May 19 (139) Behind: Recovery track, DSN 14 (1 kHz, carrier) S May 20 (140) Behind: Recovery track, DSN 14 (1 kHz, carrier) ------------------------------------------------------------------------------- Scheduled activities for Week 21: M May 21 (141) T May 22 (142) W May 23 (143) T May 24 (144) Ahead: Aphelion F May 25 (145) S May 26 (146) S May 27 (147) ------------------------------------------------------------------------------- Scheduled activities for Week 22: M May 28 (148) Memorial Day T May 29 (149) W May 30 (150) T May 31 (151) F Jun 01 (152) S Jun 02 (153) S Jun 03 (154) ------------------------------------------------------------------------------- Scheduled activities for Week 23: M Jun 04 (155) T Jun 05 (156) W Jun 06 (157) T Jun 07 (158) F Jun 08 (159) S Jun 09 (160) S Jun 10 (161) ------------------------------------------------------------------------------- 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