STEREO Weekly Meeting Minutes for 2016-03-29 (Week 13) 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 11 (Mar 14-Mar 20) * On day 077 (Mar 17) the Ahead observatory was used to phase calibrate the 1st uplink array, using DSS-24, 25, and 26 for 1.25 hours, to support the array use for STEREO Behind recovery. As the transponder data is required to do this, the space weather broadcast was delayed after the DSS-63 support by 4.25 hours and resumed at 2225z. * On day 078 (Mar 18) during the DSS-26 support, turbo decoder lock was lost briefly at 079-0012z. This anomaly resulted in the loss of one frame of SSR data. * On day 079 (Mar 19) during the DSS-55 support, turbo decoder lock was lost briefly at 1227z. This anomaly resulted in the loss of 10 frames of real-time and SSR data. * On day 080 (Mar 20) during the DSS-25 support, turbo decoder lock was lost briefly at 1811z. This anomaly resulted in the loss of one frame of SSR data. The Ahead observatory operated nominally during this week on the center of the HGA main lobe. The HGA feed assembly was at 110 degrees C and decreasing with the HGA angle at 8.9 degrees and increasing, with respect to the spacecraft-Sun line. * The average daily science data return for Ahead was 5.3 Gbits during this week. * On day 077 (Mar 17) the 1st uplink array for STEREO Behind recovery was conducted using DSS-24, 25, and 26. The uplink array was phase calibrated using the Ahead observatory first for 1.25 hours then the arrayed stations were switched to point to the Behind observatory. The configuration consisted of with the three 34m stations at the Goldstone complex using the 80 kW and two 20 kW transmitters incorporating the frequency segmented acquisition sequence with the MOC sending commands for battery recovery. At 2005z, due to all 3 stations being scheduled with the same SOA, the MOC automation software selected both DSS-25 and DSS-26 for commanding. This issue was corrected in real-time, but caused an hour delay in commanding. 174 commands were sent for battery state of charge recovery. Due to the MOC automation anomaly and the duration of the support, only 19 of the 36 frequency segments were commanded. * On day 078 (Mar 18) during the DSS-26 34m support, the 80 kW transmitter tripped off-line at 1908z and remained off-line for the final 9 minutes of the track. 256 commands were sent for battery state of charge recovery. This anomaly resulted in the loss of commanding one frequency segment. See DR# G117009 for more information. * On day 079 (Mar 19) during the DSS-26 34m support, using the 80 kW transmitter to minimize 70m contentions, 351 commands were sent for battery state of charge recovery. * On day 080 (Mar 20) during the DSS-63 70m support, some station monitor data was unavailable for the duration of the support due to a receiver controller software issue. 380 commands were sent for transmitter carrier recovery. No downlink signal was detected by the DSN. Due to the duration of the support, only 19 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. See DR# M109260 for more information. Week 12 (Mar 21-Mar 27) * On day 082 (Mar 22) during the DSS-43 support, turbo decoder lock was lost intermittently beginning at 0734z. This anomaly resulted in the loss of 466 frames of real-time and SSR data. See DR# N110255 for more information. * On day 082 (Mar 22) the 3rd PN ranging demonstration was conducted during the DSS-26 support. There was no instrument commanding or SSR playback as the DSN track services were not committed. At 083-00:00:49z and 00:01:59z, range measurements were set to zero due to no valid uplink range phase. 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. * On day 083 (Mar 23) during the DSS-26 support, turbo decoder lock was lost briefly at 2056z. This anomaly resulted in the loss of one frame of SSR data. * On day 083 (Mar 23) the 86th momentum dump was executed successfully at 2200z, which imparted an estimated delta V of 0.089 m/sec. This was the 5th momentum dump that did not use the IMU. After thruster operations completed, there was a 0.45 degree of roll angle error which was dampened out over the Page 2 of 4 next 16 minutes. Fine pointing stabilized 2.4 minutes after completion of the momentum dump. * On day 087 (Mar 27) during the DSS-26 support, turbo decoder lock was lost briefly at 088-0020z. This anomaly resulted in the loss of one frame of SSR data. * The Ahead observatory operated nominally during this week on the center of the HGA main lobe. The HGA feed assembly was at 109 degrees C and decreasing with the HGA angle at 9.1 degrees and increasing, with respect to the spacecraft-Sun line. * The average daily science data return for Ahead was 6.0 Gbits during this week. * Ahead has 12 tracks during the week, and overall coverage is nominal. There are four tracks at 720 kbps, three at 360 kbps, three at 240 kbps, and two at 160 kbps. * No Ground System anomalies/events for STEREO Behind as recovery tracks are every other week. Week 13 (Mar 28-Apr 3) * On day 088 (Mar 28) 4th PN ranging demonstration was conducted during the DSS-15 support. There was no instrument commanding or SSR playback. * On day 089 (Mar 29) MOC firmware upgrade will translate to not being able to connect with the MOC for about 2 hrs starting at ~4pm. (upgrade RAID array firmware. No tracks during this period. * A 2.6 hour DSN ranging test is scheduled for station 15 with Ahead on Monday, Mar 28. There will be no instrument commanding or SSR downlink during this pass. * Ahead has 9 passes during the week, and overall coverage is nominal. There are four passes at 720 kbps, four passes at 240 kbps, and one pass at 160 kbps. * Behind starts the week at an SPE angle of 12.3 degrees. Recovery efforts for Behind are on Friday, Saturday, and Sunday, Apr 1-3. The battery recovery tracks will be carried out with the 80 kW transmitter on station 26. The Allen Telescope Array will listen during the carrier recovery track. Week 14 (Apr 4-10) * The 33rd SECCHI stepped calibration roll is scheduled for Tuesday, Apr 5, starting at 10:45 UT. This will be the midpoint roll. System momentum is expected to be around 4 N-m-s. This will be the second stepped calibration roll without the gyros. * On Wednesday, Apr 6, the LGA uplink margin on Ahead with 70 m stations will return to the nominal 6 dB at 7.8 bps. * A 2.6 hour DSN ranging test is scheduled for Sunday, Apr 10, with station 55. There will be no instrument commanding or SSR playback during this test. * Ahead has 11 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, one at 360 kbps, five at 240 kbps, and three at 160 kbps. * Behind starts the week at an SPE angle of 12.8 degrees. There are no passes for Behind during the week. Week 15 (Apr 11-17) * Ahead has 11 passes during the week, and overall coverage is nominal. There is one pass at 720 kbps, four at 240 kbps, and six at 160 kbps. * A 5.5 hour phased uplink array pass using stations 24, 25, and 26 is scheduled for Behind battery recovery on Saturday, Apr 16, and another 7.1 hour phase uplink pass is scheduled for Sunday, Apr 17. The first approximately two hours of each pass is anticipated to be used for calibration with Ahead. Station 43 is also scheduled for three hours during the carrier recovery track on Apr 17 to listen for any signal from the Behind spacecraft. The Allen telescope array will also listen for a signal. It is not yet known whether Green Bank will be listening during the entire period. STEREO Behind will not yet be in the Arecibo field of view. * STEREO Behind starts the week at an SPE angle of 13.1 degrees. * Allocations between Ahead and Behind will be made after experience with the track on Mar 17. The NOAA antenna partners need to know when Ahead will switch to space weather mode. Week 16 (Apr 18-24) * Ahead has 14 tracks during the week, and overall coverage is nominal. There are two tracks at 720 kbps, ten at 240 kbps, and two at 160 kbps. * Behind starts the week at an SPE angle of 13.5 degrees. There are no passes for Behind during the week. Week 17 (Apr 15- May 1) * April 28 , 87th momentum dump and 6th dump not using gyro. * STB recovery tracks on Mon/Tue/Wed Week 18 (May 2- May 8) * There will be a “station return to service” track for 4 hrs at 720 kbps with no commanding and no playback. The use of 720 kbps is to test the nominal operating state. * STB no recovery tracks (every other week) Week 19 (May 9- May 15) * STEREO Ahead will use 12 tracks in total with three tracks at 720 kbps, two tracks at 360 kbps, 5 tracks at 240 kbps, and two tracks at 160 kbps. * STEREO behind begins the week at an SPE angle of 14.4 degrees. Recovery efforts for Behind are on Friday, Saturday, May 13-14. 3.2 hour phased uplink array pass using stations 24, 25, 26 is scheduled for behind battery and carrier recovery. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 13: M Mar 28 (088) Ahead: Ranging test with station 15 T Mar 29 (089) W Mar 30 (090) T Mar 31 (091) F Apr 01 (092) S Apr 02 (093) S Apr 03 (094) ------------------------------------------------------------------------------- Scheduled activities for Week 14: M Apr 04 (095) T Apr 05 (096) Ahead: SECCHI stepped calibration roll, 10:45 UT W Apr 06 (097) Ahead: Resume LGA uplink capability on 70 m DSN T Apr 07 (098) F Apr 08 (099) S Apr 09 (100) S Apr 10 (101) Ahead: Ranging test with station 55 ------------------------------------------------------------------------------- Scheduled activities for Week 15: M Apr 11 (102) T Apr 12 (103) W Apr 13 (104) T Apr 14 (105) F Apr 15 (106) S Apr 16 (107) Behind: Phased uplink array battery recovery attempt S Apr 17 (108) Behind: Phased uplink array carrier recovery attempt ------------------------------------------------------------------------------- Scheduled activities for Week 16: M Apr 18 (109) T Apr 19 (110) W Apr 20 (111) T Apr 21 (112) F Apr 22 (113) Passover begins April 22 S Apr 23 (114) S Apr 24 (115) ------------------------------------------------------------------------------- Scheduled activities for Week 17: M Apr 18 (109) Behind: recovery tracks scheduled T Apr 19 (110) Behind: recovery tracks scheduled W Apr 20 (111) Behind: recovery tracks scheduled T Apr 21 (112) F Apr 22 (113) S Apr 23 (114) S Apr 24 (115) ------------------------------------------------------------------------------- Scheduled activities for Week 18: M Apr 18 (109) “station return to service” track for 4 hrs at 720 kbps scheduled T Apr 19 (110) W Apr 20 (111) T Apr 21 (112) F Apr 22 (113) S Apr 23 (114) S Apr 24 (115) ------------------------------------------------------------------------------- Scheduled activities for Week 19: M Apr 18 (109) T Apr 19 (110) W Apr 20 (111) T Apr 21 (112) F Apr 22 (113) Behind: recovery tracks scheduled S Apr 23 (114) Behind: recovery tracks scheduled S Apr 24 (115) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2016: * 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