STEREO Weekly Meeting Minutes for 2016-05-03 (Week 18) 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 17 (Apr 25-May 1) * On day 117 (Apr 26), during the DSS-54 support for Ahead, turbo decoder lock was lost briefly at 1406z. This anomaly resulted in the loss of one frame of SSR data. * On day 118 (Apr 27), during the DSS-55 support for Ahead, turbo decoder lock was lost intermittently beginning at 0909z through 1711z. This anomaly resulted in the loss of 22 frames of real-time and SSR data. * On day 119 (Apr 28), during the DSS-25 support for Ahead, turbo decoder lock was lost intermittently beginning at 1944z through 2305z. This anomaly resulted in the loss of 3 frames of SSR data. * On day 120 (Apr 29), during the DSS-65 support for Ahead, turbo decoder lock was lost intermittently beginning at 1831z through 1853z due to weather. As 3623 frames of SSR data were not received, SSR pointers were repositioned to recover data on the next track. This anomaly resulted in the loss only a few frames of SSR data. See DR# M109332 for more information. * On day 121 (Apr 30), during the DSS-24 support for Ahead, turbo decoder lock was lost briefly at 121-0117z. This anomaly resulted in the loss of one frame of real-time telemetry data. * On day 121 (Apr 30), during the DSS-63 support for Ahead, turbo decoder lock was lost briefly at 1026z. This anomaly resulted in the loss of 2 frames of SSR data. * On day 122 (May 1), during the DSS-26 support for Ahead, turbo decoder lock was lost intermittently beginning at 123-0011z through 0058z. This anomaly resulted in the loss of 5841 frames of real-time and SSR data. See DR#G117079 for more information. This anomaly may have been the result of weather, but this has not been confirmed. * The Ahead observatory operated nominally during this week on the center of the HGA main lobe. The HGA feed assembly was at 103 degrees C and decreasing with the HGA angle at 10.3 degrees and increasing, with respect to the spacecraft-Sun line. * On day 119 (Apr 28), the 87th momentum dump was executed successfully on Ahead at 2000z, which imparted an estimated delta V of 0.117 m/sec. This was the 6th momentum dump that did not use the IMU. After thruster operations completed, there was a 1.1 degree of roll angle error which was dampened out over the next 16 minutes. Fine pointing stabilized 2.1 minutes after completion of the momentum dump. * The average daily science data return for Ahead was 5.7 Gbits during this week. * On day 116 (Apr 25), during the DSS-26 34m support for Behind, using the 80 kW transmitter to minimize 70m contentions, the transmitter tripped off-line at 1711z due to a high voltage power supply anomaly. The transmitter was re-calibrated and placed back on line at 1727z. 306 commands were sent for battery state of charge recovery. See DR# G117067 for more information. * On day 117 (Apr 26), 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 118 (Apr 27), during the DSS-63 70m support for Behind, 520 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 26 of the 36 frequency segments were commanded. Three commands must be received sequentially to power on the transmitter. * The next uplink array attempt to recover Behind will be May 13 and 14. * As time goes on, the ephemeris error increases, but the range decreases, and the combined effect results in a higher probability of success in recovering the spacecraft. 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. Station 14 has been unavailable since the end of January. The MOC will monitor this track remotely, and will send an email to the DSN about the data quality. * 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) * An additional 34th SECCHI stepped calibration roll has been inserted into the schedule on Monday, Mar 9, starting at 12:00 UT, to recalibrate the COR1 telescope after their recent change in the stray light background. The roll duration will be about 4.5 hours, and system momentum will be about 7 N-m-s. This will be the third calibration roll without using the gyros. * 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 subsequent pass durations for Behind will be 3.2 hours on May 13 for battery recovery, and 5.3 hours on May 14 for carrier recovery. The last ~40 minutes will be below 27.5 degrees elevation, so a waiver has been requested; otherwise, the broadcast power would be decreased from 80 to 40 kW. The Allen Telescope array will listen for any signal from Behind, along with DSN station 14. These passes will be attended within the MOC. 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) * Electrical maintenance will be carried out at the MOC during Memorial Day weekend. During this time, the MOC will be on generator power, starting at 5:00 PM EDT on Friday, May 27, through 8:00 PM EDT on Monday, May 30. Operations will not be affected. * 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, along with station 14. Week 22 (May 30-Jun 5) * Monday, May 30, is Memorial Day, which is an APL holiday. * The 88th momentum dump on Ahead will be carried out on Tuesday, May 31, with ignition at 20:00 UT. This will be the seventh momentum dump without using the gyros. * Ahead has 12 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, three at 360 kbps, five at 240 kbps, and two at 160 kbps. * Behind starts the week at an SPE angle of 15.0 degrees. There are no passes for Behind during the week. Week 23 (Jun 6-12) * Ahead has 9 passes during the week, and overall coverage is nominal. There are 4 passes at 720 kbps, one pass at 360 kbps, three passes at 240 kbps, and one pass at 160 kbps. * Behind starts the week at an SPE angle of 15.1 degrees. * Uplink array attempts to recover Behind are scheduled for June 11, 12. Each pass will start out with Ahead for 1.9 hours for phase calibration. There will be no instrument calibration or SSR playback during these calibration passes. Following calibration, the stations will attempt to command Behind for 3.3 hours on June 11 for battery recovery, and for 5.3 hours on June 12 for carrier recovery along with station 14. It is not yet known whether any other radio telescopes will listen for a signal from Behind during this attempt. The last 35 minutes will be below the 27.5 degree elevation limit, so a waiver will be requested. Week 24 (Jun 13-19) * Ahead has 12 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, four at 360 kbps, five at 240 kbps, and on at 160 kbps. * Behind starts the week at an SPE angle of 15.1 degrees. Because of the eccentricity of Behind's orbit, there will be a slight decrease in the SPE angle for a while. There are no tracks for Behind during the week. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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) Ahead: SECCHI stepped calibration roll, 12:00 UT 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) ------------------------------------------------------------------------------- Scheduled activities for Week 22: M May 30 (151) Memorial Day T May 31 (152) Ahead: Momentum dump, 20:00 UT W Jun 01 (153) T Jun 02 (154) F Jun 03 (155) S Jun 04 (156) S Jun 05 (157) ------------------------------------------------------------------------------- Scheduled activities for Week 23: M Jun 06 (158) T Jun 07 (159) W Jun 08 (160) T Jun 09 (161) F Jun 10 (162) S Jun 11 (163) Behind: Phased array recovery attempt S Jun 12 (164) Behind: Phased array recovery attempt ------------------------------------------------------------------------------- Scheduled activities for Week 24: M Jun 13 (165) T Jun 14 (166) W Jun 15 (167) T Jun 16 (168) F Jun 17 (169) S Jun 18 (170) S Jun 19 (171) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2016: * Jun 15 STEREO Subsystem 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