STEREO Weekly Meeting Minutes for 2018-04-10 (Week 15) ANNOUNCEMENTS ------------- * Attempts to recover Behind will shift to back to a monthly schedule from the current weekly schedule. Weekly attempts will end in week 16, and the monthly attempts will pick up 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 weekly schedule to attempt to recover the spacecraft. Passes are scheduled approximately every three days to keep within the 72 hour command loss timer. Typically, two of those days use a search pattern consisting of two diamonds, based on the estimated uncertainty in the ephemeris. The double diamond pattern is executed twice, once to send commands, and then again 40 minutes later to listen for the carrier. An additional pass uses the standard configuration. In some cases, the older "1 kHz" frequency acquisition sequence is used, with one day for battery recovery, and another for carrier recovery. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 14 (Apr 2-8) * On day 097 (Apr 7), the SECCHI instrument on Ahead reset at 21:29:57z. The SECCHI team reconfigured the instrument to operational mode by 098-1300z. This was the 49th reset of the SECCHI instrument on the Ahead observatory. * The average daily science data return for Ahead was 7.0 Gbits during this week. * On day 092 (Apr 2), 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 094 (Apr 4), during a 3.8 hour 1 kHz battery recovery support for Behind with DSS-43, 297 commands were transmitted for battery state of charge recovery. Due to the duration of the support, only 30 of the 36 frequency segments were commanded. * On day 097 (Apr 7), during a 3.25 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. Week 15 (Apr 9-15) * The DSN is using the space weather beacon signal from STEREO to run tests for two cubesats accompanying the InSight mission to Mars. This has no effect on STEREO operations. * The 108th momentum dump on Ahead was carried out this morning (Apr 10), with ignition at 15:00 UT. * Ahead has 15 passes during the week, and overall coverage is nominal. There are six tracks at 720 kbps, three at 360 kbps, and six at 240 kbps. * Search pattern recovery tracks for Behind are scheduled for Monday, Apr 9 (battery) and Wednesday, Apr 11 (carrier). 1 kHz frequency acquisition recovery tracks are scheduled for Saturday, Apr 14 (battery) and Sunday, Apr 15 (carrier). Week 16 (Apr 16-22) * The NASA TESS launch is scheduled for late Monday, Apr 16, with a launch window opening at 22:32 UTC. There are some contingencies effects for STEREO if the launch slips, mainly for Behind. * 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. * 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. Week 18 (Apr 30-May 6) * The NASA InSight launch is scheduled for Saturday, May 5, between 11:05-13:05 UT. DSN contingency plans in case of launch slippage are still TBD. * 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 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 reached 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. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 15: M Apr 09 (099) Behind: Recovery track, DSN 14 (search pattern, battery) T Apr 10 (100) Ahead: Momentum dump, 15:00 UT W Apr 11 (101) Behind: Recovery track, DSN 14 (search pattern, carrier) T Apr 12 (102) F Apr 13 (103) S Apr 14 (104) Behind: Recovery track, DSN 43 (1 kHz, battery) S Apr 15 (105) Behind: Recovery track, DSN 14 (1 kHz, carrier) ------------------------------------------------------------------------------- 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) S Apr 29 (119) Notes: * Behind has transitioned to a monthly recovery schedule. * High cadence COR2 measurements planned during the week (TBC) ------------------------------------------------------------------------------- Scheduled activities for Week 18: M Apr 30 (120) 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) ------------------------------------------------------------------------------- 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