STEREO Weekly Meeting Minutes for 2016-02-02 (Week 05) ANNOUNCEMENTS ------------- * None INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally, back on the main lobe of the high gain antenna. * There are currently no communications with the Behind spacecraft. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 04 (Jan 25-31) * On day 026 (Jan 26), during the DSS-43 support for Ahead, turbo decoder lock was lost briefly at 0834z during the final minute of SSR playback. This anomaly resulted in the loss of 33 frames of real-time and SSR data. * On day 028 (Jan 28), during the DSS-54 support for Ahead, turbo decoder lock was lost briefly at 1011z. This anomaly resulted in the loss of one frame of real-time and SSR data. * On day 030 (Jan 30), during the DSS-26 support for Ahead, turbo decoder lock was lost intermittently between 1732z through 031-0015z. This anomaly resulted in the loss of 572 frames of real-time telemetry and SSR data. * On day 031 (Jan 31), during the DSS-45 support for Ahead, initial telemetry lock was delayed 12 minutes at 0547z due to heavy rain at the Canberra complex. This anomaly resulted in the loss of 1202 frames of spacecraft SSR playback and real-time data. See DR# C111776 for more information. * On day 031 (Jan 31), a TTC version 1.1 demonstration was conducted during the DSS-55 support for Ahead. There was no instrument commanding or SSR playback as the DSN track services were not committed. * On day 031 (Jan 31), during the DSS-25 support for Ahead, turbo decoder lock was lost intermittently between 2151z through 2304z. At 2305z, the antenna was stowed due to sustained high winds. After the winds subsided, telemetry lock was re-established at 2326z. The track continued one-way only for the remaining 1.3 hours. This anomaly resulted in the loss of 21 minutes of real-time telemetry, commanding, tracking data and SSR data. See DR# G116930 for more information. * 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 7.7 degrees and increasing, with respect to the spacecraft-Sun line. * On day 027 (Jan 27), 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 028 (Jan 28), during the DSS-26 34m support for Behind, the 80 kW transmitter tripped off-line at 1949z and was placed back on-line at 2006z. 256 commands were sent for battery state of charge recovery. The anomaly resulted in not commanding one frequency segment. See DR# G116923 for more information. * On day 030 (Jan 30), 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 05 (Feb 1-7) * Ahead has 10 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, three passes at 240 kbps, and four passes at 160 kbps. * Behind starts the week at an SPE angle of 8.3 degrees. Recovery efforts for Behind are Monday, Tuesday, and Thursday, Feb 1-4. The battery conditioning tracks will be undertaken with the 80 kW transmitter on station 26. Week 06 (Feb 8-14) * The 32nd SECCHI stepped calibration roll will be carried out on Tuesday, Feb 9, starting at 09:00 UT. This will be the first stepped calibration roll since solar conjunction, and the first one without using the gyros. The duration has been increase by about an hour to accommodate the longer settling time, making the total duration about 4.5 hours. * The third EEPROM refresh on both IMUs on STEREO Ahead will be carried out on Wednesday, Feb 10. This refresh is recommended by the manufacturer, and is carried out every three years. The IMUs will be powered up, 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. * 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. Other * The SSC reports that a software anomaly resulted in no SECCHI real-time beacon images being processed over the weekend. These days will be filled in once the playback telemetry has been processed. * There was some discussion about the effect of the STEREO roll excursions on the SECCHI HI data. The timescale of these excursions, 10-20 minutes, are too long to be classified as jitter. Roll excursions on these timescales have been seen ever since going to reduced gyro operations in September 2013, but have increased significantly in amplitude after conjunction, and are larger than they should be. The higher cadence data needed to understand the problem didn't start coming down until the resumption of normal operations in mid-November. The effect of the larger amplitude on the HI data is that the double-star images are interfering with the star-identification needed to calibrate the instrument pointing. The MOC was unaware of the large observing durations of the HI data, 30 minutes for HI-1 and 99 minutes for HI-2. The original pointing specifications for STEREO were concentrated on the needs of the Sun-pointed telescopes. * There was some discussion about using the STEREO real-time telemetry visualizer in later versions of Windows. Java has to be installed in a particular manner for the telemetry visualizer to work. It has not yet been tested in Windows 10. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 05: M Feb 01 (032) T Feb 02 (033) W Feb 03 (034) T Feb 04 (035) F Feb 05 (036) S Feb 06 (037) S Feb 07 (038) ------------------------------------------------------------------------------- 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) Behind: First recovery attempt using uplink phased array F Mar 18 (078) S Mar 19 (079) S Mar 20 (080) ------------------------------------------------------------------------------- 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