STEREO Weekly Meeting Minutes for 2016-03-01 (Week 09) 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 08 (Feb 22-28) * On day 053 (Feb 22), during the DSS-26 support for Ahead, turbo decoder lock was lost intermittently beginning at 1915z through 2233z. This anomaly resulted in the loss of 26 frames of real-time and SSR playback data. * On day 054 (Feb 23), the 2nd 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 were not committed. At 00:00:35z, a range measurement was 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. See DR# G116971 for more information. * On day 055 (Feb 24), during the DSS-55 support for Ahead, telemetry lock was lost intermittently beginning at 1643z through 1648z due to heavy rain at the Madrid complex. This anomaly resulted in the loss of 4991 frames or 4.7 minutes of spacecraft SSR playback and real-time data. See DR# M109228 for more information. * On day 055 (Feb 24), during the DSS-25 support for Ahead, the transmitter tripped off-line at 2228z due to a network issue. This anomaly resulted in the loss of 331 frames of real-time data during the transition from two-way to one-way. While the transmitter became operational at 2320z, to avoid further real-time data loss, MOps elected to remain one-way for the remainder of the track. See DR# G116974 for more information. * On day 056 (Feb 25), during the DSS-26 support for Ahead, turbo decoder lock was lost briefly at 057-0000z. This anomaly resulted in the loss of 1 frame of SSR playback data. * On day 057 (Feb 26), during the DSS-63 support for Ahead, turbo decoder lock was lost intermittently beginning at 1340z through 1345z. SSR pointers were repositioned to minimize data loss. Later in the track, turbo decoder lock was again lost intermittently between 1517z and 1551z. This anomaly resulted in the loss of 16,234 frames or 3.3 minutes of real-time and SSR playback data. Both anomalies are attributed to bad weather conditions at DSS-63. See DR #M109231 for more information. * On day 057 (Feb 26), the planned DSS-24 support was switched to use DSS-15 and shortened by 55 minutes off the end with a new duration of 2.5 hours to assist the SOHO mission with their warm start recovery. DSS-14 shadowed this entire support to test predicts. * On day 059 (Feb 28), prior to the DSS-65 support for Ahead, the primary Ahead MOC workstation hung due to a hardware anomaly, preventing the telemetry bind from occurring. The backup command workstation also failed the telemetry bind. MOC staff remotely monitoring detected the issues. The primary command workstation was manually rebooted prior to the next support and the command and telemetry application was restarted on the backup workstation to resolve the anomalies. This resulted in no real-time telemetry being received in the MOC as well as no commanding throughout the entire track (1415z/1745z). No data loss resulted from these anomalies since the DSN continued to transmit IDR files into the archive throughout the MOC outage. * The Ahead observatory operated nominally during this week on the center of the HGA main lobe. The HGA feed assembly was at 113 degrees C and decreasing with the HGA angle at 8.4 degrees and increasing, with respect to the spacecraft-Sun line. * On day 053 (Feb 22), the 85th momentum dump on Ahead was executed successfully at 2200z, which imparted an estimated delta V of 0.103 m/sec. This was the 4th momentum dump that did not use the IMU. After thruster operations completed, there was a 2.9 degree of roll angle error which was dampened out over the next 20 minutes. Fine pointing stabilized 1.9 minutes after completion of the momentum dump. * On day 055 (Feb 24), the G&C control bandwidth (Ctl.Bw) parameter for science pointing was adjusted in RAM on Ahead at 1215z. While the roll error has improved, performance throughout a momentum cycle will be monitored. This update is attempting to minimize the increase in roll error that has affected SECCHI HI images intermittently since exiting solar conjunction. * The average daily science data return for Ahead was 5.2 Gbits during this week. * On day 057 (Feb 26), during the DSS-26 34m support for Behind, using the 80 kW transmitter to minimize 70m contentions, 297 commands were sent for battery state of charge recovery. * On day 058 (Feb 27), during the DSS-26 34m support for Behind, using the 80 kW transmitter to minimize 70m contentions, 189 commands were sent for battery state of charge recovery. * On day 059 (Feb 28), during the DSS-43 70m support for Behind, 440 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 22 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. Week 09 (Feb 29-Mar 6) * Turbo decoder lock was lost briefly during the station 45 pass for Ahead yesterday (Feb 29), resulting in the loss of about 90 frames of data. * 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 4.75 hour battery recovery track using stations 24, 25, and 26. * A downlink source is needed to calibrate the stations for uplink array. Ahead will be used for this purpose just before the pass for Behind. To allow this to happen, Ahead will be commanded to the 160 kbps downlink rate at the end of the station 63 pass at 18:00 UT on Mar 17, instead of switching to the space weather beacon rate as usual. The switch to the beacon rate will be delayed until 22:25 UT. The 4.75 hour pass for Behind will be split between the calibration on Ahead for about 2 hours, with the rest on Behind. * 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. All four passes are within 72 hours of each other. * 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, there will be one track for battery recovery, and another for carrier acquisition. Week 12 (Mar 21-27) * A 2.75 hour DSN ranging test is scheduled for station 26 with Ahead on Mar 22. There will be no instrument commanding or SSR downlink during this pass. * The 86rd momentum dump for Ahead is scheduled for Wednesday, Mar 23, with ignition at 22:00 UT. This will be the 5th momentum dump without the gyros. * Ahead has 12 passes during the week, and overall coverage is nominal. There are four passes at 720 kbps, three passes at 360 kbps, three passes at 240 kbps, and two passes at 160 kbps. * Behind starts the week at an SPE angle of 11.9 degrees. There will be no passes for Behind. From this point on, attempts to contact Behind will occur only every other week, with phased uplink arrays used once per month. Week 13 (Mar 28-Apr 3) * 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. 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. * 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. STEREO Behind will not yet be in the Arecibo field of view. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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) Ahead: Broadcasting at 160 kbps between 18:00-22:25 UT Behind: First recovery attempt using uplink phased array F Mar 18 (078) S Mar 19 (079) S Mar 20 (080) ------------------------------------------------------------------------------- Scheduled activities for Week 12: M Mar 21 (081) T Mar 22 (082) Ahead: Ranging test with station 26 W Mar 23 (083) Ahead: Momentum dump, 22:00 UT T Mar 24 (084) F Mar 25 (085) S Mar 26 (086) S Mar 27 (087) ------------------------------------------------------------------------------- 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 ------------------------------------------------------------------------------- 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