STEREO Weekly Meeting Minutes for 2016-04-05 (Week 14) 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 13 (Mar 28-Apr 3) * On day 088 (Mar 28), the 4th 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 089-00:00:42z and 00:01:52z, 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 091 (Mar 31), during the DSS-25 support for Ahead, turbo decoder lock was lost intermittently beginning at 1801z through 2341z. This anomaly resulted in the loss of 3 frames of real-time and SSR data. * On day 093 (Apr 2), during the DSS-63 support for Ahead, turbo decoder lock was lost intermittently beginning at 1234z through 1237z. This anomaly resulted in the loss of 27 frames of real-time and 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 9.4 degrees and increasing, with respect to the spacecraft-Sun line. * The average daily science data return for Ahead was 4.8 Gbits during this week. * On day 092 (Apr 1), during the DSS-26 34m support for Behind, using the 80 kW transmitter to minimize 70m contentions, 351 commands were sent for battery state of charge recovery. * On day 093 (Apr 2), 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 094 (Apr 3), during the DSS-63 70m support for Behind, 580 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 28 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. Week 14 (Apr 4-10) * The 33rd SECCHI stepped calibration roll occurred this morning, Apr 5, starting at 10:45 UT. This was the midpoint roll. This was the second stepped calibration roll without the gyros. Data from the roll was coming down during the telecon. * Tomorrow, Apr 6, the LGA uplink margin on Ahead with 70 m stations will return to the nominal 6 dB at 7.8 bps. The LGA downlink margin won't return to nominal until the end of the year. * G&C rate merging will be enabled in RAM at 11:00 tomorrow. This should give a better rate estimate, and improve the X-axis roll error. Earlier, on Feb 24, the control bandwidth was tightened, which improved the roll error--this should also contribute to an improvement. The rates which will be merged are from the star tracker and guide telescope. System performance will be monitored for several hours, in case the change needs to be rolled back. * 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 1.9 hours of each pass will 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. The last hour of the track will be below 27.5 degrees elevation. A waiver has been requested; otherwise the broadcast power would need to be reduced. * STEREO Behind starts the week at an SPE angle of 13.1 degrees. 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 25-May 1) * The 87th momentum dump on Ahead is scheduled for Thursday, Apr 28, with ignition at 20:00 UT. This will be the 6th momentum dump without using the gyros. * Ahead has 12 tracks during the week, and overall coverage is nominal. There are 3 tracks 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 13.8 degrees. Recovery efforts for Behind are on Monday-Wednesday, Apr 25-27. The battery recovery tracks will be undertaken with the 80 kW transmitter on station 26. Week 18 (May 2-8) * There will be a return to service track with station 14 for 4 hrs at 720 kbps on Saturday, May 7. There will be no instrument commanding or SSR playback during this track. The use of 720 kbps is to test the nominal operating state. * Ahead has 10 track during the week, and overall coverage is nominal. There are two tracks at 720 kbps, two at 360 kbps, five at 240 kbps, and one at 160 kbps. * Behind starts the week at an SPE angle of 14.1 degrees. There are no tracks for Behind during the week. Week 19 (May 9-15) * Ahead has 12 tracks during the week, and overall coverage is nominal. There are three tracks at 720 kbps, two at 360 kbps, five at 240 kbps, and two at 160 kbps. * Behind starts the week at an SPE angle of 14.4 degrees. Phased uplink array passes for Behind recovery are scheduled for May 13 and 14. The first 1.9 hours each day will be with Ahead to calibrate the antenna phasing. There will be no instrument commanding or SSR playback during these calibration passes. These passes with Ahead show up in the DSN schedules, so the NOAA antenna partners will know when Ahead will or will not be in space weather broadcast mode. The last 47 minutes will be below 27.5 degrees elevation, so there will need to be either a waiver, or a decrease in broadcast power. Week 20 (May 16-22) * Ahead has 13 tracks during the week, and overall coverage is nominal. There are two tracks at 720 kbps, two at 360 kbps, five at 240 kbps, and two at 160 kbps. * Behind starts the week at an SPE angle of 14.6 degrees. There are no tracks for Behind during the week. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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) S Apr 23 (114) S Apr 24 (115) ------------------------------------------------------------------------------- Scheduled activities for Week 17: M Apr 25 (116) T Apr 26 (117) W Apr 27 (118) T Apr 28 (119) Ahead: Momentum dump, 20:00 UT F Apr 29 (120) S Apr 30 (121) S May 01 (122) ------------------------------------------------------------------------------- Scheduled activities for Week 18: M May 02 (123) T May 03 (124) W May 04 (125) T May 05 (126) F May 06 (127) S May 07 (128) Ahead: Return-to-service track with station 14 S May 08 (129) ------------------------------------------------------------------------------- Scheduled activities for Week 19: M May 09 (130) T May 10 (131) W May 11 (132) T May 12 (133) F May 13 (134) Behind: Phased array recovery attempt S May 14 (135) Behind: Phased array recovery attempt S May 15 (136) ------------------------------------------------------------------------------- Scheduled activities for Week 20: M May 16 (137) Post Solar Conjunction Assessment Review T May 17 (138) W May 18 (139) T May 19 (140) F May 20 (141) S May 21 (142) S May 22 (143) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2016: * 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