STEREO Weekly Meeting Minutes for 2015-12-29 (Week 53) ANNOUNCEMENTS ------------- * None INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna with a one degree offset. * There are currently no communications with the Behind spacecraft. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 52 (Dec 21-27) * On day 355 (Dec 21), during the ESA DSS-74 New Norcia support for Ahead, the command uplink was lost at 0545z due to a transmitter issue. The support remained downlink only for the duration. This anomaly resulted in the loss of 5 hours of commanding and two-way tracking data, along with 57 telemetry frames, and 3 frames of real-time data. * On day 356 (Dec 22), during the DSS-14 support for Ahead, initial telemetry acquisition occurred 41 minutes late at 1711z due to a transmitter issue. SSR pointers were repositioned to minimize data loss. This anomaly resulted in the loss of 41 minutes real-time telemetry, one hour of commanding and two-way tracking data, 3.3 hours of SECCHI SSR data, and the SWAVES science partition overwriting for 1.4 hours on day 358 (Dec 24). * On day 360 (Dec 26), during the DSS-63 support, turbo decoder lock was lost briefly at 1225z. This anomaly resulted in the loss of three frames of real-time data. * The Ahead observatory operated nominally during this week resuming operations on the HGA main lobe riding along a one degree offset to prevent overheating of the HGA feed assembly which was at 120-121 degrees C with the HGA angle at 7.1 degrees, with respect to the spacecraft-Sun line. After 15 months of side lobe and superior solar conjunction operations, on day 321, November 17th, nominal daily science operations resumed. * On day 355 (Dec 21), the 83rd momentum dump on Ahead was executed successfully at 2000z, which imparted a delta V of 0.119 m/sec. While this was the 2nd momentum dump that did not use the IMU, it was the first full momentum dump with the momentum target set to the nominal 15 Nms. The spacecraft had a 2.3 degree roll error at the end of the dump which took several minutes to damp out. Fine pointing stabilized 1.9 minutes after completion of the momentum dump. Considering the lack of high rate data, as expected, the dump is less efficient. An estimated 36 grams of propellant was used, which is 29% higher than a typical dump with gyros. Continuing to perform momentum dumps once per month at an average cost of 36 grams/dump, remaining propellant will be expended in 95.6 years. * On day 358, the SWAVES SSR science partition (#13) on Ahead filled and began overwriting at 2036z for 1.4 hours. This was due to the late initial acquisition for the DSS-14 support on day 356. * The average daily science data return for Ahead, with the HGA on the main lobe riding along a one degree offset, was 3.9 Gbits during this week. * On day 358 (Dec 24), during the DSS-43 70m support for Behind, 288 commands were sent for battery state of charge recovery. * On day 359 (Dec 25), during the DSS-43 70m support for Behind, 288 commands were sent for battery state of charge recovery. * On day 360, during the DSS-43 70m support, 380 commands were sent for transmitter carrier recovery. The DSN did not detect the downlink signal. 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 5th uplink array test on Ahead is scheduled for January 14th, testing the use of three 34m stations using the 80 kW and two 20 kW transmitters with the HGA main lobe. This should provide twice the uplink received power as a 70m station. When the uplink array capability is ready, it will be used to increase the spacecraft received signal power to assist with Behind recovery commanding. * SECCHI reports that they see no imaging data in the level-0 files for Thursday, Dec 24, though the housekeeping data are there. The level-0 files for Dec 23 and 25 are as expected. The SSC reports that no SECCHI beacon telemetry was received for that day, though beacon telemetry for the other instruments were received without problem. Week 53 (Dec 28-Jan 3) * The downlink rate for 70 meter stations for Ahead was increase to the maximum rate of 720 kbps yesterday (Dec 28). The HGA will be centered on the main lobe tomorrow (Dec 30). From that point on the HGA temperature should start to decrease, though it will take until late spring for the temperature to cool significantly. * APL will be closed for a half day on Thursday, Dec 31, and for a full day on Friday, Jan 1, for the New Year holiday. * Ahead has 10 tracks during the week, and overall coverage is nominal. Seven tracks are at 720 kbps, and three at 160 kbps. * Behind starts the week at an SPE angle of 5.7 degrees. Recovery efforts for Behind are Wednesday, Thursday, and Friday, Dec 30-Jan 1. * If Behind is recovered by then, the high gain antenna will be on the main lobe with a 1 degree offset on Jan 2. Week 01 (Jan 4-10) * Ahead has 10 tracks during the week, and overall coverage is nominal. There are four tracks at 720 kbps, two at 240 kbps, and four at 160 kbps. * Behind starts the week at an SPE angle of 6.2 deg. Recovery efforts for Behind are Monday, Tuesday, and Wednesday, Jan 4-6. The battery recovery tracks will be performed with the 80 kW transmitter on station 26. Week 02 (Jan 11-17) * The 32nd SECCHI stepped calibration roll on Ahead is tentatively scheduled for Tuesday, Jan 12, starting at 12:30 UT, depending on both the MOC and SECCHI being ready. This will be the first stepped roll without the IMU. System momentum is expected to be about 4 N-m-s. The duration of the calibration roll be about 4.5 hours. * 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 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. 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. * 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 four passes at 720 kbps, two 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 Friday-Saturday, Jan 20-23. The first track 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 Wednesday, Feb 1-3. The battery recovery tracks will be undertaken with the 80 kW transmitter on station 26. Week 06 (Feb 8-14) * 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 recovery tracks will be undertaken with the 80 kW transmitter on station 26. * Behind will be at aphelion on Friday, Feb 12. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 53: M Dec 28 (362) Ahead: Main lobe, riding soft stop, 720 kbps (70 m) T Dec 29 (363) W Dec 30 (364) Ahead: HGA on main lobe T Dec 31 (365) F Jan 01 (001) New Year S Jan 02 (002) S Jan 03 (003) ------------------------------------------------------------------------------- Scheduled activities for Week 01: M Jan 04 (004) T Jan 05 (005) W Jan 06 (006) T Jan 07 (007) F Jan 08 (008) S Jan 09 (009) S Jan 10 (010) ------------------------------------------------------------------------------- Scheduled activities for Week 02: M Jan 11 (011) T Jan 12 (012) Ahead: First NGO SECCHI stepped calib. roll 12:30 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) S Feb 13 (044) S Feb 14 (045) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2016: * Jan 2 Behind: HGA on main lobe, offpoint 1 degree, 240 kbps Behind: Resume space weather broadcast to NOAA stations * Jan 5 Behind: HGA on main lobe, riding soft stop, 360 kbps Behind: SSR playback and reconfiguration * Jan 6 Behind: Instrument recommissioning, IMPACT SWEA/STE on * Jan 9 Behind: HGA on main lobe, riding soft stop, 480 kbps * Jan 11 Behind: HGA on main lobe, riding soft stop, 720 kbps * Jan 12 Behind: HGA on main lobe * Jan 27 Both: HGA calibration (NGO) * 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