STEREO Weekly Meeting Minutes for 2018-04-17 (Week 16) ANNOUNCEMENTS ------------- * This is the last week for weekly attempts to recover Behind. Monthly recovery attempts will start in week 20. 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 15 (Apr 9-15) * On day 100 (Apr 10), during the DSS-55 support for Ahead, turbo decoder lock was lost intermittently at 1658z through 1704 due to rain at the Madrid complex. This anomaly resulted in the loss of 146 frames of real-time telemetry and SSR data. See DR# M110537 for more information. * On day 104 (Apr 14), during the DSS-55 support for Ahead, turbo decoder lock was lost briefly at 1526z, 1530z, and 1808z. This anomaly resulted in the loss of five frames of real-time telemetry and SSR data. * On day 100 (Apr 10), the 108th momentum dump on Ahead was executed successfully at 1500z, which imparted an estimated delta V of 0.091 m/sec. This was the 27th momentum dump that did not use the IMU. After thruster operations completed, there was a 0.77 degree of roll angle error which was dampened out over the next 9.8 minutes. Fine pointing stabilized 2.3 minutes after completion of the momentum dump. * The average daily science data return for Ahead was 7.0 Gbits during this week. * On day 099 (Apr 9), 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 101 (Apr 11) during a 3 hour 4 kHz carrier recovery search pattern support for Behind with DSS-14, 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 104 (Apr 14), during a 2.6 hour 1 kHz battery recovery support for Behind with DSS-43, 198 commands were transmitted for battery state of charge recovery. Due to the duration of the support, only 22 of the 36 frequency segments were commanded. * On day 105 (Apr 15), during a 3.5 hour 1 kHz carrier recovery support for Behind with DSS-14, 380 commands were sent for transmitter carrier recovery. No carrier was detected by either the DSN station. Due to the duration of the support and the increased commands for each step, only 19 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. Week 16 (Apr 16-22) * A SECCHI guide-telescope-driven offpoint is scheduled for Wednesday, Apr 18, starting at 14:20 UT. This is to test the alignment of the COR1 occulter. Images will be taken at four positions 15 arcseconds apart, out to one arcminute. A total of 80 minutes has been allocated for this activity. * The NASA TESS launch has been rescheduled for tomorrow, Apr 18. The STEREO DSN schedule is unaffected. * The DSN is carrying out antenna attenuation tests tomorrow (Apr 18) using the space weather beacon signal from Ahead, in preparation for the InSight mission. * Ahead has 17 passes during the week, and overall coverage is nominal. There are six tracks at 720 kbps, five at 360 kbps, and six at 240 kbps. * Search pattern recovery tracks for Behind are scheduled for Tuesday, Apr 17 (battery), and Friday, Apr 20 (carrier). A nominal 4 kHz recovery sequence is scheduled for Sunday, Apr 22. * This is 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. * 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, 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. * 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. * Ahead has 14 passes during the week, and overall coverage is nominal. There are six passes at 720 kbps, one at 360 kbps, and seven at 240 kbps. * There are no recovery passes scheduled for Behind during the week. Week 20 (May 14-20) * The 104th 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. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 16: M Apr 16 (106) T Apr 17 (107) Behind: Recovery track, DSN 14 (search pattern, battery) W Apr 18 (108) Ahead: SECCHI offpoint, 14:20 UT (80 minutes) T Apr 19 (109) F Apr 20 (110) Behind: Recovery track, DSN 43 (search pattern, carrier) S Apr 21 (111) S Apr 22 (112) Behind: Recovery track, DSN 14 (4 kHz) ------------------------------------------------------------------------------- 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) ------------------------------------------------------------------------------- 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