STEREO Weekly Meeting Minutes for 2016-02-09 (Week 06) 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 05 (Feb 1-7) * On day 034 (Feb 3), the latest level zero file versions for SECCHI days 030, 01, and 032 and for SWAVES for days 030 through 033 were empty due to an assessment disk filling at the MOC. Disk space was freed and new versions of the level zero files for days 030 through 033 were created. * On day 035 (Feb 4), during the DSS-26 support for Ahead, turbo decoder lock was lost intermittently between 2147z through 036-0024z. This anomaly resulted in the loss of 14 frames of SSR playback data. * On day 036 (Feb 5), during the DSS-26 support for Ahead, turbo decoder lock was lost intermittently between 1845z through 037-0027z. This anomaly resulted in the loss of 16 frames of SSR playback data. * On day 038 (Feb 7), during the DSS-26 support for Ahead, the IDR file ingestion process at the MOC stopped at 2318z due to a directory filling. The directory was cleaned and all IDR files were re-ingested and reprocessed. At 2335z, turbo decoder lock was lost briefly resulting in the loss of 7 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 116 degrees C and decreasing with the HGA angle at 7.8 degrees and increasing, with respect to the spacecraft-Sun line. * The average daily science data return for Ahead was 4.3 Gbits during this week. * On day 032 (Feb 1), during the DSS-26 34m support for Behind, using the 80 kW transmitter to minimize 70m contentions, 270 commands were sent for battery state of charge recovery. * On day 033 (Feb 2), during the DSS-26 34m support for Behind, using the 80 kW transmitter to minimize 70m contentions, 189 commands were sent for battery state of charge recovery. * On day 035 (Feb 4), during the DSS-43 70m support for Behind, 380 commands were sent for transmitter carrier recovery. 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. * The last uplink array test was on Jan 14, using stations 24, 25 at 20 kW, and station 26 at 80 kW. The resulting uplink power was 4 times that of a 70 meter station. The next uplink test will be on Feb 19, and will include the segmented frequency acquisition mode. If the successful, uplink arraying will be used operationally for the first time on the Behind spacecraft on March 17. Week 06 (Feb 8-14) * The 32nd SECCHI stepped calibration roll was carried out this morning (Feb 9), starting at 09:00 UT. This was be the first stepped calibration roll since solar conjunction, and the first one without using the gyros. The duration has been increased by about an hour to accommodate the longer settling time, making the total duration about 4.5 hours. * After the calibration roll, intermittent dropouts were seen during the station 63 pass, due to weather. * The third EEPROM refresh on both IMUs on STEREO Ahead will be carried out tomorrow (Feb 10). This refresh is recommended by the manufacturer, and is carried out every three years. The IMUs will be powered up for about 30-45 minutes, but disabled. The operation takes a few minutes, and IMUs will be powered down again at the end. * Behind will be at aphelion on Friday, Feb 12. * Ahead has 12 passes during the week, and overall coverage is nominal. There are four passes at 720 kbps, two passes at 240 kbps, and six passes at 160 kbps. * Behind starts the week at an SPE angle of 8.8 degrees. Recovery efforts for Behind are on Friday, Saturday, and Sunday, Feb 12-14. The battery conditioning tracks will be undertaken with the 80 kW transmitter on station 26. Week 07 (Feb 15-21) * The sixth and final uplink array test with Ahead will be carried out on 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 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. * 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. * A question was raised as to whether the Ahead spacecraft can continue to be used as a calibration for the phased uplink array passes for Behind as the spacecraft continue to separate from each other. Modelling suggests that this is expected to happen sometime in late 2017 or early 2018. However, after that point it may be possible to use the Moon for calibration. Phased uplink of arrays is not an operational capability for the DSN; it is experimental and still being optimized. 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. Other * A question was raised about DSN support for older versions of the Space Link Extension (SLE) standard. Some missions have been asked to test using the new SLE version. However, STEREO has not been asked to do any testing. DSN will continue to support version 1 for the next couple of years, through the current STEREO extended mission. If STEREO is extended again, then work will be needed to migrate to the new SLE version. 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) ------------------------------------------------------------------------------- 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