STEREO Weekly Meeting Minutes for 2018-04-24 (Week 17) ANNOUNCEMENTS ------------- * Because of a problem with a filled disk partition, some telemetry files produced today (Apr 24) incorrectly show zero file size. 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 16 (Apr 16-22) * On day 109 (Apr 19), during the DSS-43 support for Ahead, turbo lock was lost intermittently between 0437z and 0443z. This anomaly resulted in the loss of 3 frames of SSR data. * On day 109 (Apr 19), during the DSS-55 support for Ahead, turbo lock was lost briefly at 1316z. This anomaly resulted in the loss of 4 frames of SSR data. * On day 112 (Apr 22), during the DSS-35 support for Ahead, telemetry lock was lost intermittently between 0146z and 0220z and again between 0407z and 0418z. This anomaly resulted in the loss of 15,446 frames of real-time telemetry and SSR data, which is equivalent to about 7 minutes at the 360 kbps rate. See DR #C113376 for more information. * On day 112 (Apr 22), during the DSS-55 support for Ahead, telemetry lock was lost intermittently between 1034z and 1035z. This anomaly resulted in the loss of 5 frames of SSR data. * On day 108 (Apr 18), at 1420z, the 12th SECCHI GT Calibration Offpoint event on Ahead was conducted. This offpoint was conducted to test how much the COR1 occulter had moved over the course of the mission, and whether there was any danger of the solar image moving off the edge of the occulter. This test showed that there was no danger of the solar image not being properly occulted for the foreseeable future. * The average daily science data return for Ahead was 7.7 Gbits during this week. * On day 107 (Apr 17), during a 3 hour 4 kHz battery recovery search pattern support for Behind with DSS-14, 320 commands were transmitted during the support. All 7 points on the pattern were covered twice. * On day 110 (Apr 20), during a 3 hour 4 kHz carrier recovery search pattern support with DSS-43, 320 commands were transmitted during the support for carrier recovery. No carrier was detected by the DSN station. All 7 points on the pattern were covered twice. Three commands must be received sequentially to power on the transmitter. * On day 112 (Apr 22), during a 3.2 hour 4 kHz carrier recovery support for Behind with DSS-14, 320 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 interfacebus off. * This was the last week for weekly attempts to recover Behind. Monthly attempts will pick up in week 20. Week 17 (Apr 23-29) * Ahead has 12 passes during the week, and overall coverage is nominal. There are six passes at 720 kbps, three at 360 kbps, and three at 240 kbps. * There are no recovery passes scheduled for Behind during the week. * SECCHI will be running a COR2 deep exposure campaign between Apr 28-30. Track coverage should be good during this period. This campaign may have an effect on the beacon data--this still needs to be determined. Week 18 (Apr 30-May 6) * The NASA InSight launch is scheduled for Saturday, May 5, between 11:05-13:05 UT. The MOC has been adjusting a few tracks, and the schedule currently looks okay for any launch contingency. * 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 no less than 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 14 passes during the week, and overall coverage is nominal. There are eight passes at 720 kbps, four at 240 kbps, and two 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 13 passes during the week, and overall coverage is nominal. There are nine passes at 720 kbps, two at 360 kbps, and two 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 17: M Apr 23 (113) T Apr 24 (114) W Apr 25 (115) T Apr 26 (116) F Apr 27 (117) S Apr 28 (118) Ahead: SECCHI/COR2 deep exposure campaign S Apr 29 (119) Ahead: SECCHI/COR2 deep exposure campaign Notes: * Behind has transitioned to a monthly recovery schedule. ------------------------------------------------------------------------------- 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