STEREO Weekly Meeting Minutes for 2018-02-20 (Week 8) ANNOUNCEMENTS ------------- * None 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 7 (Feb 12-18) * On day 043 (Feb 12), during the DSS-26 support for Ahead, no telemetry was received due to receiver being declared red. SSR pointers were repositioned during the next track to minimize data loss. This anomaly resulted in the loss of 174 minutes of commanding and real-time telemetry. All SSR data were received. See DR #G118939 for more information. * On day 044 (Feb 13), during the pre-calibration for the DSS-14 support for Ahead, the DSN was unable to perform range calibrations. Later in the support, turbo decoder lock was lost intermittently at 045-0222z through 045-0243z. This anomaly resulted in the loss of 8 frames of SSR data. See DR #G118944 for more information. * On day 045 (Feb 14), during the pre-calibration for the DSS-14 support for Ahead, the DSN was unable to perform range calibrations. The station delay was set to zero. Later in the support, turbo decoder lock was lost briefly at 1943z. These anomalies resulted in the loss of 1 frame of SSR data. See DR #G118951 for more information. * On day 045 (Feb 14), a Return-To-Service (RTS) engineering demo was conducted with DSS-43 with Ahead. The purpose was to validate X-band tracking performance after the completion of the depot level maintenance. The MOC received real-time telemetry and sent four commands successfully. As the tracking, telemetry, and command data from this support were non-committed, the SSR was not played back and no instrument commands were sent. * On day 046 (Feb 15), during the DSS-63 support for Ahead, initial acquisition of telemetry was 12 minutes late at 1742z due to an antenna drive issue at the station. This anomaly resulted in the loss of 12 minutes of real-time telemetry, commanding, and tracking data and 94 frames of SSR data. See DRs #M110468 for more information. * On day 047 (Feb 16), during the DSS-43 support for Ahead, turbo decoder lock was lost briefly at 0707z. This anomaly resulted in the loss of 11 frames of SSR data. * On day 047 (Feb 16), during the pre-calibration for the DSS-14 support for Ahead, the DSN was unable to perform range calibrations. The station delay was set to zero. See DR #G118956 for more information. * On day 048 (Feb 17), during the pre-calibration for the DSS-14 support for Ahead, the DSN was unable to perform range calibrations. The station delay was set to zero. See DR #G118956 for more information. * On day 048 (Feb 17), during the DSS-43 support for Ahead, turbo decoder lock was lost intermittently at 0303z through 0305z. This anomaly resulted in the loss of 22 frames of SSR data. * On day 048 (Feb 17), during the DSS-55 support, turbo decoder lock was lost briefly at 1351z. This anomaly resulted in the loss of 2 frames of SSR data. * The average daily science data return for Ahead was 6.7 Gbits during this week. * On day 044 (Feb 13), during a 3 hour 4 kHz carrier recovery search pattern support for Behind with DSS-14, 302 commands were transmitted during the support for carrier recovery. No carrier was detected by either the DSN station or the radio science receiver team. All 7 points on the pattern were covered twice. Three commands must be received sequentially to power on the transmitter. * On day 047 (Feb 16), during a 3.5 hour 1 kHz carrier recovery support for Behind with DSS-63, 270 commands were sent for transmitter carrier recovery. No carrier was detected by either the DSN station or the radio science receiver team. Due to the duration of the support and the increased commands for each step, only 30 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. * On day 049 (Feb 18), during a 4 hour 1 kHz carrier recovery support for Behind with DSS-63, 440 commands were sent for transmitter carrier recovery. No carrier was detected by either the DSN station or the radio science receiver team. Due to the duration of the support and the increased commands for each step, only 22 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. Week 8 (Feb 19-25) * The 42nd SECCHI stepped calibration roll is being carried out during the telecon (Feb 20). * Work will be performed on the JPL network for four hours starting at 22:45 UT on Thursday, Feb 22 lasting for four hours. There are no STEREO tracks during this period. * Ahead has 14 tracks during the week, and overall coverage is nominal. There are eight tracks at 720 kbps, four at 360 kbps, and two at 240 kbps. * Recovery search pattern tracks for Behind are scheduled for Tuesday, Feb 20 (battery) and Wednesday, Feb 21 (carrier). 1 kHz frequency acquisition sequence recovery tracks are scheduled for Saturday, Feb 24 (battery) and Sunday, Feb 25 (carrier). Week 9 (Feb 26-Mar 4) * Ahead has 10 tracks during this week, and overall coverage is nominal. There are six tracks at 720 kbps, one at 360 kbps, and three at 240 kbps. * Recovery search pattern tracks for Behind are scheduled for Tuesday, Feb 27 (battery) and Friday, Mar 2 (carrier), and a 1 kHz frequency acquisition sequence recovery track is scheduled for Sunday, Mar 4 (battery). Week 10 (Mar 5-11) * The second Mercury transit for Ahead on Monday, Mar 5. The SSC estimates that Mercury will transit through the EUVI field-of-view between approximately 23:20 UT on Mar 4 and 8:15 UT on Mar 5, and through the COR1 field-of-view between 17:30 UT on Mar 4 and 14:30 UT on Mar 5. The MOC calculates that Mercury will cross the solar disk between 02:25 and 05:27 UT on Mar 5. Two DSN tracks on that day have been promoted to level 3 on station 35 and station 55. * The 107th momentum dump is scheduled for Monday, Mar 5, starting at 16:00 UT. This is the 26th dump without the gyros. * Daylight savings time in the U.S. begins Sunday, Mar 11. * Ahead has 13 tracks during this week, and overall coverage is nominal. There are two tracks at 720 kbps, four at 360 kbps, and seven at 240 kbps. * A nominal 4 kHz recovery track for Behind is scheduled for Tuesday, May 6. Search pattern tracks are scheduled for Thursday, Mar 8 (battery), and Saturday Mar 10 (carrier). Week 11 (Mar 12-18) * Ahead has 15 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, two at 360 kbps, six at 240 kbps, and one at 160 kbps. * A battery recovery search pattern track for Behind is scheduled for Monday, Mar 12, and a nominal 4 kHz carrier recovery track is scheduled for Wednesday, Mar 14. 1 kHz frequency acquisition recovery tracks are scheduled for Friday, Mar 16 (battery), and Sunday, Mar 18 (carrier). Week 12 (Mar 19-25) * Ahead has 14 tracks during the week, and overall coverage is nominal. There are eight tracks at 720 kbps, three at 360 kbps, and three at 240 kbps. * Search pattern recovery tracks for Behind are scheduled for Tuesday, Mar 20 (battery) and Wednesday, Mar 21 (carrier). A 1 kHz frequency acquisition sequence battery recovery track is scheduled for Saturday, Mar 24. Week 13 (Mar 26-Apr 1) * Passover begins Friday, March 30 and goes through April 7. Good Friday is March 30, and April 1 is Easter. * March 31 is aphelion for the Behind S/C. * Ahead has 16 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, four at 360 kbps, and six at 240 kbps. * A 1 kHz frequency acquisition sequence carrier recovery track is scheduled Monday, Mar 26. Search pattern recovery tracks are scheduled for Wednesday, Mar 28 (battery), and Saturday, Mar 31. A 1 kHz frequency acquisition sequence battery recovery track is scheduled for Sunday, Apr 1. Week 14 (Apr 2-8) * Ahead has 18 passes during the week, and overall coverage is nominal. There are eight passes at 720 kbps, five at 360 kbps, and five at 240 kbps. * Carrier recovery search pattern tracks for Behind are scheduled for Monday, Apr 2, and Saturday, Apr 7. A 1 kHz frequency acquisition battery recovery track is scheduled for Wednesday, Apr 4. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 08: M Feb 19 (050) President's Day T Feb 20 (051) Ahead: SECCHI calibration roll, 12:30 UT Behind: Recovery track, DSN 63 (search pattern, battery) W Feb 21 (052) Behind: Recovery track, DSN 43 (search pattern, carrier) T Feb 22 (053) F Feb 23 (054) S Feb 24 (055) Behind: Recovery track, DSN 63 (1 kHz, battery) S Feb 25 (056) Behind: Recovery track, DSN 63 (1 kHz, carrier) ------------------------------------------------------------------------------- Scheduled activities for Week 09: M Feb 26 (057) T Feb 27 (058) Behind: Recovery track, DSN 14 (search pattern, battery) W Feb 28 (059) T Mar 01 (060) F Mar 02 (061) Behind: Recovery track, DSN 14 (search pattern, carrier) S Mar 03 (062) S Mar 04 (063) Behind: Recovery track, DSN 14 (1 kHz, battery) ------------------------------------------------------------------------------- Scheduled activities for Week 10: M Mar 05 (064) Ahead: Mercury transit, 02:25-05:27 UT Ahead: Momentum dump, 16:00 UT T Mar 06 (065) Behind: Recovery track, DSN 43 (4 kHz) W Mar 07 (066) T Mar 08 (067) Behind: Recovery track, DSN 43 (search pattern, battery) F Mar 09 (068) S Mar 10 (069) Behind: Recovery track, DSN 43 (search pattern, carrier) S Mar 11 (070) Daylight Savings Time begins in US ------------------------------------------------------------------------------- Scheduled activities for Week 11: M Mar 12 (071) Behind: Recovery track, DSN 14 (search pattern, battery) T Mar 13 (072) W Mar 14 (073) Behind: Recovery track, DSN 14 (4 kHz) T Mar 15 (074) F Mar 16 (075) Behind: Recovery track, DSN 43 (1 kHz, battery) S Mar 17 (076) S Mar 18 (077) Behind: Recovery track, DSN 14 (1 kHz, carrier) ------------------------------------------------------------------------------- Scheduled activities for Week 12: M Mar 19 (078) T Mar 20 (079) Behind: Recovery track, DSN 14 (search pattern, battery) W Mar 21 (080) Behind: Recovery track, DSN 14 (search pattern, carrier) T Mar 22 (081) F Mar 23 (082) S Mar 24 (083) Behind: Recovery track, DSN 43 (1 kHz, battery) S Mar 25 (084) ------------------------------------------------------------------------------- Scheduled activities for Week 13: M Mar 26 (085) Behind: Recovery track, DSN 43 (1 kHz, carrier) T Mar 27 (086) W Mar 28 (087) Behind: Recovery track, DSN 43 (search pattern, battery) T Mar 29 (088) F Mar 30 (089) S Mar 31 (090) Behind: Recovery track, DSN 14 (search pattern, carrier) S Apr 01 (091) Behind: Recovery track, DSN 14 (1 kHz, battery) ------------------------------------------------------------------------------- Scheduled activities for Week 14: M Apr 02 (092) Behind: Recovery track, DSN 14 (search pattern, carrier) T Apr 03 (093) W Apr 04 (094) Behind: Recovery track, DSN 43 (1 kHz, battery) T Apr 05 (095) F Apr 06 (096) S Apr 07 (097) Behind: Recovery track, DSN 14 (search pattern, carrier) S Apr 08 (098) ------------------------------------------------------------------------------- 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