STEREO Weekly Meeting Minutes for 2016-04-12 (Week 15) 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 14 (Apr 4-10) * On day 095 (Apr 4), during the DSS-63 support for Ahead, turbo decoder lock was lost intermittently beginning at 1813z through 1820z. This anomaly resulted in the loss of 168 frames of real-time and SSR data. See DR# N110270 for more information. * On day 097 (Apr 6), during the DSS-55 support for Ahead, turbo decoder lock was lost briefly at 1258z. This anomaly resulted in the loss of one frame of SSR data. * On day 098 (Apr 7), during the DSS-25 support for Ahead, turbo decoder lock was lost briefly at 2331z. This anomaly resulted in the loss of one frame of SSR data. * On day 099 (Apr 8), during the DSS-26 support for Ahead, turbo decoder lock was lost intermittently beginning at 2322z through 100-0200z. This anomaly resulted in the loss of 31,737 frames of real-time and SSR data, which is equivalent to about 20 minutes of downlink time. See DR# N110271 for more information. No definite reason has been established, but it shows the characteristics of being weather related. * On day 100 (Apr 9), during the DSS-15 support for Ahead, turbo decoder lock was lost briefly at 1459z. This anomaly resulted in the loss of one frame of SSR data. * On day 100 (Apr 9), during the DSS-26 support for Ahead, turbo decoder lock was lost intermittently beginning at 2315z through 101-0003z. This anomaly resulted in the loss of 4072 frames of real-time and SSR data, which is equivalent to about 3 minutes of downlink time. See DR# N110272 for more information. * On day 101 (Apr 10), the 5th PN ranging demonstration using DSS-15 with Ahead was cancelled to assist the Kepler mission with recovery from a spacecraft emergency. * On day 101 (Apr 10), during the DSS-25 support for Ahead, turbo decoder lock was lost briefly at 2030z and again at 2243z. This anomaly resulted in the loss of 2 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 108 degrees C and decreasing with the HGA angle at 9.6 degrees and increasing, with respect to the spacecraft-Sun line. * On day 096 (Apr 5), the 33rd SECCHI stepped calibration was executed at 1045z for midpoint in the orbit. This was the 2nd SECCHI stepped calibration roll to be conducted without gyro use. Note that the G&C control bandwidths that were loaded on day 055 for improving roll error were in effect for each data collection step. SECCHI/COR1 reports that this roll was quite successful. * On day 097 (Apr 6), the G&C rate-merge algorithm was enabled in RAM on Ahead at 1131z. This algorithm was developed post-launch (in 2009) and enables rate measurements from all sensors to be combined to form a "better" rate estimate versus picking only one G&C sensor as the source of the angular rate measurement. While the X-axis jitter 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 short term jitter in roll appears to be improved, but the excursions on longer time scales appears to be unaffected. However, the tightened bandwidth back in March resulted in a big improvement in the SECCHI/HI performance. The MOC will continue to look at the spacecraft pointing behavior post conjunction. * The average daily science data return for Ahead was 5.6 Gbits during this week. * There were no tracks for Behind during the week. Attempts to recover Behind have been reduced to every other week. Week 15 (Apr 11-17) * 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, after which the spacecraft will go back to space weather mode. 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 from 80 to 40 kW. * 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. * 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 from 80 to 40 kW. The Allen Telescope array will listen for any signal from Behind, along with DSN station 14. 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. Week 21 (May 23-29) * Ahead has 14 tracks during the week, and overall coverage is nominal. There are three tracks at 720 kbps, seven at 240 kbps, and four at 160 kbps. * Behind starts the week at an SPE angle of 14.8 degrees. Recovery efforts for Behind are on Friday-Sunday, May 27-29. The battery recovery tracks will be undertaken with the 80 kW transmitter on station 26. The Allen Telescope Array will also be listening during the transmitter recovery track. Other * The post solar conjunction assessment review will occur sometime in May. The data for this has not yet been determined. 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) ------------------------------------------------------------------------------- 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) T May 17 (138) W May 18 (139) T May 19 (140) F May 20 (141) S May 21 (142) S May 22 (143) ------------------------------------------------------------------------------- Scheduled activities for Week 21: M May 23 (144) T May 24 (145) W May 25 (146) T May 26 (147) F May 27 (148) S May 28 (149) S May 29 (150) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2016: * May Post Solar Conjunction Assessment Review (date TBD) * 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