STEREO Weekly Meeting Minutes for 2016-01-12 (Week 02) 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 01 (Jan 4-10) * On day 004 (Jan 4), during the DSS-63 support for Ahead, turbo decoder lock was lost intermittently between 1021z through 1147z due to a station tracking issue. This anomaly resulted in the loss of 190 frames of real-time and SSR data. See DR #N110208 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 118 degrees C and decreasing with the HGA angle at 7.3 degrees and increasing, with respect to the spacecraft-Sun line. * On day 010 (Jan 10), the SECCHI instrument reset at 14:05:41z. The SECCHI team reconfigured the instrument to operational mode by 010-2200z. This was the 38th reset of SECCHI on the Ahead observatory. * The average daily science data return for Ahead was 4.4 Gbits during this week. * On day 004 (Jan 4), during the DSS-26 34m support for Behind, using the 80 kW transmitter to minimize 70m contentions, 186 commands were sent for battery state of charge recovery. * On day 005 (Jan 5), 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 006 (Jan 6), during the DSS-14 70m support for Behind, 380 commands were sent for transmitter carrier recovery. The Allen Telescope Array observed concurrently, however, no downlink signal was detected by them or 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. * A question was raised about the large amount of data loss during week 51. This was primarily due to station 63 being red, along with a late acquisition for a station 14 pass. The effects of this were carried into the following week. * Part of the data loss can also be attributed to SECCHI having an anomaly where the instrument did not properly read its schedule at the start of the day. This happened twice, on Dec 24, and Jan 3. The SECCHI team has traced this down to a couple of bugs in their software relating to leap years, and are working on a fix. They've also implemented a different method of scheduling to avoid the error. They are currently working on verifying that these fixes solve the problem. Week 02 (Jan 11-17) * The SECCHI stepped calibration roll on Ahead has been postponed due to the scheduling problems that the SECCHI team has been experiencing, as discussed above. The next window for performing a calibration roll is in the first two weeks of February. SECCHI expects that they'll know by the end of the week whether or not the problem is fixed. * Ahead will be at perihelion on Thursday, Jan 14. * The fifth uplink array test is scheduled for Thursday, Jan 14, with stations 24 and 25 at 20 kW, and station 26 at 80 kW. The received power at the satellite is expected to be roughly twice that of a 70 meter station. The test duration will be about 4 hours. There will be no instrument commanding or SSR playback during this test. The uplink rate will be 7.8 bps during the test, and downlink will be non-coherent. * Ahead has 9 passes during the week, and overall coverage is nominal. There are five passes at 720 kbps, one at 240 kbps, and three at 160 kbps. * Behind starts the week at an SPE angle of 6.7 degrees. Recovery efforts for Behind are Friday, Saturday, and Sunday, Jan 11-17. The first two tracks will be undertaken with station 26 using the 80 kW transmitter. The Allen and Green Bank telescopes will listen during the telemetry recovery track. Week 03 (Jan 18-24) * A 2.6 hour ranging test with station 15 with Ahead will be carried out on Monday, Jan 18. There will be no instrument commanding or SSR playback during this test. The telemetry rate will be 160 kbps. * The 84th momentum dump for Ahead is scheduled for Thursday, Jan 21, with ignition at 23:00 UT. The telemetry rate will be 160 kbps. The telemetry performance during the previous dump on Dec 21 was very good. * Ahead has 10 passes during the week, and overall coverage is nominal. There are four passes at 720 kbps, two passes at 240 kbps, and four passes at 160 kbps. * Behind starts the week at an SPE angle of 7.2 deg. Recovery efforts for Behind are Monday, Tuesday, and Wednesday, Jan 18-20. The Tuesday pass will be undertaken with station 26 using the 80 kW transmitter. Week 04 (Jan 25-31) * Ahead has 11 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, three passes at 240 kbps, and six passes at 160 kbps. * Behind starts the week at an SPE angle of 7.7 degrees. Recovery efforts for Behind are Wednesday, Thursday, and Saturday, Jan 20-23. The first two tracks will be undertaken with station 26 using the 80 kW transmitter. 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) * 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. Combining array phasing with the frequency segmented acquisition mode is very challenging. If this test works, then it will be ready for use with the Behind recovery efforts, possibly in March. The uplink rate will be 7.8 bps, and the downlink will be non-coherent. 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. * 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. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 02: M Jan 11 (011) T Jan 12 (012) W Jan 13 (013) T Jan 14 (014) Ahead: Perihelion Ahead: Uplink array test with stations 24,25,26 F Jan 15 (015) S Jan 16 (016) S Jan 17 (017) ------------------------------------------------------------------------------- Scheduled activities for Week 03: M Jan 18 (018) Ahead: Ranging test with station 15 T Jan 19 (019) W Jan 20 (020) T Jan 21 (021) Ahead: Momentum dump, 23:00 UT F Jan 22 (022) S Jan 23 (023) S Jan 24 (024) ------------------------------------------------------------------------------- Scheduled activities for Week 04: M Jan 25 (025) T Jan 26 (026) W Jan 27 (027) T Jan 28 (028) F Jan 29 (029) S Jan 30 (030) S Jan 31 (031) ------------------------------------------------------------------------------- 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) W Feb 10 (041) 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) W Feb 24 (055) T Feb 25 (056) F Feb 26 (057) S Feb 27 (058) S Feb 28 (059) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2016: * Mar 3 Behind: Resume LGA uplink capability on 70 m DSN * 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