STEREO Weekly Meeting Minutes for 2016-02-16 (Week 07) ANNOUNCEMENTS ------------- * None INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * There are currently no communications with the Behind spacecraft. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 06 (Feb 8-14) * There were a number of problems with loss of telemetry lock or Turbo decoder lock during the week. Many of these were due to weather, or to station problems, but there were also a few instances of problems with Turbo decoder lock that has been seen over the course of the mission, leading to losses of small amounts of data. These problems had seemed to have been cleared up, but are apparently coming back again. The signal-to-noise ratio is quite good, with several dB of margin, so the problem is not due to a weak signal. * On day 040 (Feb 9), during the DSS-63 support for Ahead, telemetry lock was lost intermittently beginning at 1432z through 1656z due to heavy rain at the Madrid complex. This anomaly resulted in the loss of 2874 frames of spacecraft SSR playback and real-time data. See DR# M109186 for more information. * On day 041 (Feb 10), during the DSS-55 support for Ahead, telemetry lock was lost briefly at 1244z during fault isolation of an alarm at the station which affected the antenna pointing. This anomaly resulted in the loss of 1217 frames of spacecraft SSR playback and real-time data. See DR# M109187 for more information. * On day 041 (Feb 10), during the DSS-26 support for Ahead, turbo decoder lock was lost intermittently between 2155z through 042-0038z. This anomaly resulted in the loss of 9 frames of SSR playback data. * On day 042 (Feb 11), during the DSS-35 support for Ahead, turbo decoder lock was lost intermittently between 0748z through 0804z due to heavy rain at the Canberra complex. The transmitter tripped off-line at 0810z and remained off through EOT 15 minutes later. These anomalies resulted in the loss of 14 minutes of commanding and two-way tracking data and 859 frames of SSR playback data. See DR# C111809 and C111810 for more information. * On day 043 (Feb 12), during the DSS-43 support for Ahead, turbo decoder lock was lost briefly at 0819z. This anomaly resulted in the loss of 2 frames of SSR playback data. * On day 043 (Feb 12), during the DSS-65 support for Ahead, telemetry lock was lost intermittently beginning at 1526z through 1549z due to rain at the Madrid complex. This anomaly resulted in the loss of 226 frames of spacecraft SSR playback and real-time data. See DR# M109193 for more information. * On day 044 (Feb 13), during the DSS-65 support for Ahead, telemetry lock was lost intermittently beginning at 1125z through 1708z due to heavy rain at the Madrid complex. This anomaly resulted in the loss of 6599 frames of spacecraft SSR playback and real-time data. * On day 045 (Feb 14), during the DSS-43 support for Ahead, turbo decoder lock was lost intermittently between 0724z through 0744z. This anomaly resulted in the loss of 147 frames of SSR playback and real-time data. * On day 045 (Feb 14), during the DSS-26 support for Ahead, turbo decoder lock was lost intermittently between 2058z through 2326z. This anomaly resulted in the loss of 6 frames of SSR playback data. * The Ahead observatory operated nominally during this week on the center of the HGA main lobe. The HGA feed assembly was at 115 degrees C and decreasing with the HGA angle at 8.0 degrees and increasing, with respect to the spacecraft-Sun line. * On day 040 (Feb 9), the 32nd SECCHI stepped calibration on Ahead was executed at 0900z for perihelion in the orbit. This was the first SECCHI stepped calibration roll to be conducted without gyro use and post solar conjunction as well. The SECCHI team is still examining the data, but preliminary indications are that the roll went well. * On day 041 (Feb 10), the 3rd IMU EEPROM refresh on Ahead was conducted at 1155z refreshing the EEPROM data in both IMU units as required by the manufacturer. * On day 042 (Feb 11), a new IS table was loaded to SECCHI at 1416z. * The average daily science data return for Ahead was 4.8 Gbits during this week. * On day 043 (Feb 12), during the DSS-26 34m support for Behind, using the 80 kW transmitter to minimize 70m contentions, 225 commands were sent for battery state of charge recovery. * On day 044 (Feb 13), during the DSS-26 34m support for Behind, using the 80 kW transmitter to minimize 70m contentions, 243 commands were sent for battery state of charge recovery. * On day 045 (Feb 14), during the DSS-43 70m support for Behind, 375 commands were sent for transmitter carrier recovery. Five commands were not sent at 1235z due to a timing error at the station. No downlink signal was detected by the DSN. 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. See DR# M109211 for more information. Week 07 (Feb 15-21) * Turbo lock was lost briefly during the station 26 pass for Ahead yesterday (Feb 15), resulting in the loss of 2 frames of data. * The sixth and final uplink array test with Ahead will be carried out on Friday afternoon, Feb 19. This will combine the previously tested phased array of stations 24, 25 at 20 kW, and station 26 at 80 kW, with the frequency segmented acquisition mode for recovering Behind. The total pass duration is 4 hours. Combining array phasing with the frequency segmented acquisition mode is very challenging. The uplink rate will be 7.8 bps, and the downlink will be non-coherent at 160 kbps. There will be no instrument commanding or SSR playback during the test. * Ahead has 9 passes during the week, and overall coverage is nominal. There are four passes at 720 kbps, two at 240 kbps, and three at 160 kbps. * Behind starts the week at an SPE angle of 9.4 degrees. Recovery efforts for Behind are on Friday, Saturday, and Sunday, Feb 19-21. The battery conditioning track on Saturday will be carried out with the 80 kW transmitter on station 26. Week 08 (Feb 22-28) * The 85th momentum dump on Ahead is scheduled for Monday, Feb 22, with ignition at 22:00 UT. This will be the fourth no-gyro momentum dump. * A 2.6 hour DSN ranging test will be carried out using station 15 on Tuesday, Feb 23. There will be no instrument commanding or SSR playback during this track. * Ahead has 13 passes during the week, and overall coverage is nominal. There are four passes at 720 kpbs, three at 240 kbps, and six at 160 kbps. * Behind starts the week at an SPE angle of 9.9 degrees. Recovery efforts for Behind are on Friday, Saturday, and Sunday, Feb 26-28. The battery conditioning tracks will be carried out with the 80 kW transmitter on station 26. Week 09 (Feb 29-Mar 6) * On Thursday, Mar 3, the uplink margin on the Behind LGA with 70 meter stations returns to 6 dB at 7.8 bps. * Ahead has 13 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, seven at 240 kbps, and four at 160 kbps. * Behind starts the week at an SPE angle of 10.4 degrees. Recovery efforts for Behind are on Thursday, Friday, and Sunday, Mar 3-6. The battery recovery tracks will be carried out with the 80 kW transmitter on station 26. Week 10 (Mar 7-13) * Daylight Savings Time starts in the U.S. on Sunday, Mar 13. * Ahead has 13 passes during the week, and overall coverage is nominal. There are seven passes at 720 kbps, one at 360 kbps, two at 240 kbps, and three at 160 kbps. It is possible to go to 360 kbps with station 26 if the elevation is above 25 degrees for the entire pass. * Behind starts the week at an SPE angle of 10.9 degrees. Recovery efforts for Behind are on Friday, Saturday, and Sunday, Mar 11-13. The battery recovery tracks will be carried out with the 80 kW transmitter on station 26. Week 11 (Mar 14-20) * The first uplink array pass for Behind will be on Thursday, Mar 17. This will be a 4.75 hour battery recovery track using stations 24, 25, and 26. * A downlink source is needed to calibrate the stations for uplink array. Ahead will be used for this purpose just before the pass for Behind. To allow this to happen, Ahead will remain at the 160 kbps downlink rate at the end of the station 63 pass at 18:00 UT on Mar 17, instead of switching to the space weather beacon rate as usual. The switch to the beacon rate will be delayed until 22:25 UT. The 4.75 hour pass for Behind will be split between the calibration on Ahead for about 2 hours, with the rest on Behind. * Ahead has 11 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, two passes at 360 kbps, four passes at 240 kpbs, and two passes at 160 kbps. * Behind starts the week at an SPE angle of 11.4 degrees. Besides the phased array pass on Thursday, Mar 17, recovery efforts for Behind are on Friday, Saturday, and Sunday, Mar 18-20. The battery recovery tracks will be carried out with the 80 kW transmitter on station 26. * After this week, recovery efforts for Behind will be reduced to every two weeks, with phased array attempts once per month. For the phased array attempts, one of the two battery recovery tracks will use the phased array configuration, along with the carrier acquisition track. Week 12 (Mar 21-27) * A 2.75 hour DSN ranging test is scheduled for station 26 with Ahead on Mar 22. There will be no instrument commanding or SSR downlink during this pass. * Ahead has 12 passes during the week, and overall coverage is nominal. There are four passes at 720 kbps, three passes at 360 kbps, three passes at 240 kbps, and two passes at 160 kbps. * Behind starts the week at an SPE angle of 11.9 degrees. There will be no passes for Behind. From this point on, attempts to contact Behind will occur only every other week, with phased uplink arrays used once per month. Week 13 (Mar 28-Apr 3) * A 2.6 hour DSN ranging test is scheduled for station 15 with Ahead on Monday, Mar 28. There will be no instrument commanding or SSR downlink during this pass. * Ahead has 9 passes during the week, and overall coverage is nominal. There are four passes at 720 kbps, four passes at 240 kbps, and one pass at 160 kbps. * Behind starts the week at an SPE angle of 12.3 degrees. Recovery efforts for Behind are on Friday, Saturday, and Sunday, Apr 1-3. The battery recovery tracks will be carried out with the 80 kW transmitter on station 26. Other * The MOC continues to look into the increased X-axis roll errors which have been affected the SECCHI HI images. They anticipate adjusting G&C parameters to try to minimize the roll errors. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 06: M Feb 08 (039) T Feb 09 (040) Ahead: SECCHI calibration roll, 9 UT W Feb 10 (041) Ahead: IMU EEPROM refresh T Feb 11 (042) F Feb 12 (043) Behind: Aphelion S Feb 13 (044) S Feb 14 (045) ------------------------------------------------------------------------------- Scheduled activities for Week 07: M Feb 15 (046) T Feb 16 (047) W Feb 17 (048) T Feb 18 (049) F Feb 19 (050) Ahead: Uplink array test with stations 24,25,26 S Feb 20 (051) S Feb 21 (052) ------------------------------------------------------------------------------- Scheduled activities for Week 08: M Feb 22 (053) Ahead: Momentum dump, 22:00 UT T Feb 23 (054) Ahead: DSN ranging test with station 15 W Feb 24 (055) T Feb 25 (056) F Feb 26 (057) S Feb 27 (058) S Feb 28 (059) ------------------------------------------------------------------------------- Scheduled activities for Week 09: M Feb 29 (060) T Mar 01 (061) W Mar 02 (062) T Mar 03 (063) Behind: Resume LGA uplink capability on 70 m DSN F Mar 04 (064) S Mar 05 (065) S Mar 06 (066) ------------------------------------------------------------------------------- Scheduled activities for Week 10: M Mar 07 (067) T Mar 08 (068) W Mar 09 (069) T Mar 10 (070) F Mar 11 (071) S Mar 12 (072) S Mar 13 (073) Daylight Savings Time starts in U.S. ------------------------------------------------------------------------------- Scheduled activities for Week 11: M Mar 14 (074) T Mar 15 (075) W Mar 16 (076) T Mar 17 (077) Ahead: Remain at 160 kbps between 18:00-22:25 UT Behind: First recovery attempt using uplink phased array F Mar 18 (078) S Mar 19 (079) S Mar 20 (080) ------------------------------------------------------------------------------- Scheduled activities for Week 12: M Mar 21 (081) T Mar 22 (082) Ahead: Ranging test with station 26 W Mar 23 (083) T Mar 24 (084) F Mar 25 (085) S Mar 26 (086) S Mar 27 (087) ------------------------------------------------------------------------------- Scheduled activities for Week 13: M Mar 28 (088) T Mar 29 (089) W Mar 30 (090) T Mar 31 (091) F Apr 01 (092) S Apr 02 (093) S Apr 03 (094) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2016: * Apr 6 Ahead: Resume LGA uplink capability on 70 m DSN * May 16 Both: Post Solar Conjunction Assessment Review * Jul 5 Juno arrival at Jupiter * Dec Behind: Resume LGA downlink capability on 70 m DSN 2017: 2018: * Mar 5 Ahead: Mercury transit 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