STEREO Weekly Meeting Minutes for 2016-01-26 (Week 04) 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 03 (Jan 18-24) * The MOC status remained nominal during the massive snowstorm that hit the Washington area over the weekend, keeping up with tracking the spacecraft and with downloading telemetry. * On day 018 (Jan 18), a PN ranging demonstration was conducted during the DSS-15 support for Ahead. There was no instrument commanding or SSR playback as the DSN track services are not committed. At 2254z, telemetry lock was lost due to receiver issue. A second receiver was placed on-line at 2321z. The DSN reported partial success for this demonstration. The new PN ranging system transmits all of the tones at the same time, reducing the cycle time for acquiring range lock, and thus increases the number of range points collected during a support. PN ranging is also easier to use because only one navigation-centric variable is needed: integration time, instead of T1 and T2. See DR# G116896 and G116898 for more information. * On day 021 (Jan 21), MOps was alerted that DSS-35 had been declared red due to an X-band receiver issue with an ETRO of day 027-0542z. The on board timetags for the scheduled day 023 support for Ahead were deleted to prevent SSR data loss. This anomaly resulted in the loss of 5.2 hours of commanding and two-way tracking data. See DR# C111709 for more information. * On day 023 (Jan 23), during the DSS-54 track for Ahead, real-time telemetry and monitor data were not received in the MOC between 1337z and 1650z (EOT) due to the SLE telemetry bind being dropped as a result of a network issue at JPL. Post pass, it was noticed that no IDR files were created during the outage period. The DSN created the IDR files and all SSR data was recovered. This anomaly resulted in the loss of 3.2 hours of real-time telemetry and monitor data. See DR# N110230 for more information. * On day 023, during the DSS 26 track for Ahead, a transmitter glitch caused the command system to abort at 2359z. This anomaly had no impact, as it occurred after the commanding window had expired, approaching EOT. See DR# G116910 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 7.6 degrees and increasing, with respect to the spacecraft-Sun line. * On day 021 (Jan 21), the 84th momentum dump on Ahead was executed successfully at 2300z, which imparted an estimated delta V of 0.110 m/sec. This was the 3rd momentum dump that did not use the IMU. After thruster operations completed, there was a 1.1 degree of roll angle error which was dampened out over the next 20 minutes. Fine pointing stabilized 2.2 minutes after completion of the momentum dump. * The average daily science data return for Ahead was 5.0 Gbits during this week. • On day 018 (Jan 18), during the DSS-43 70m support for Behind, 342 commands were sent for battery state of charge recovery. • On day 019 (Jan 19), during the DSS-26 34m support for Behind, using the 20 kW transmitter as the 80 kW transmitter was red, 234 commands were sent for battery state of charge recovery. See DR# G116903 for more information. • On day 020 (Jan 20), during the DSS-14 70m support, 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. Week 04 (Jan 25-31) * The 3.7 hour station 55 pass on Sunday, Jan 31, has been converted into a DSN tracking test pass. There is plenty of coverage from other passes during this period. There will be no instrument commanding or SSR playback during the station 55 pass. * Ahead has 10 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, three passes at 240 kbps, and five passes at 160 kbps. * Behind starts the week at an SPE angle of 7.7 degrees. Recovery efforts for Behind are Wednesday, Thursday, and early Saturday, Jan 27-30. 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) * 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. The MOC is making slight modifications to the script used three years ago. These modifications are currently being tested. * Behind will be at aphelion on Friday, Feb 12. * SECCHI reports that they are now able to support a calibration roll, and requests that the next one be scheduled during week 6. The MOC will go ahead and schedule the roll, probably near the beginning of the week. * 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. There will be no instrument commanding or SSR playback during the test. * If this test works, then it will be ready for use with the Behind recovery efforts, starting in March, and once a month thereafter. The phased array configuration will be requested twice for each test, once for battery conditioning, and once for carrier recovery. The overall frequency of Behind recovery efforts will be reduced to every other week. * 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 12 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, six 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. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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) Ahead: DSN tracking test with station 55 ------------------------------------------------------------------------------- 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) 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. ------------------------------------------------------------------------------- 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