STEREO Weekly Meeting Minutes for 2016-04-26 (Week 17) ANNOUNCEMENTS ------------- * It was omitted from last week's minutes that the Green Bank Observatory also supported the Apr 17 attempt to contact the Behind spacecraft, along with the Allen Telescope Array. 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 16 (Apr 18-24) * On day 109 (Apr 18), during the DSS-34 support for Ahead, system noise temperature monitor data was unavailable for the duration of the track due to an equipment anomaly at the station. See DR# C112007 for more information. * On day 110 (Apr 19), during the DSS-65 support for Ahead, initial telemetry lock was delayed 40 minutes until 0855z due to rain at the Madrid complex. A second downlink receiver was added with the same result. Telemetry lock was lost again at 0937z through the end of track due to heavy rain again. These anomalies resulted in the loss of 3.6 hours of commanding, tracking, and real-time telemetry data. As SSR pointers were repositioned during the following support, only a few frames of SSR data were lost during the transition from two-way to one-way. See DR# M109304 and M109305 for more information. * On day 110 (Apr 19), during the DSS-25 support for Ahead, SSR pointers were repositioned to their locations corresponding to the start of the previous track, DSS-65, to minimize data loss. Later, turbo decoder lock was lost briefly at 1924z and again at 2336z. This anomaly resulted in the loss of 3 frames of SSR data. * On day 111 (Apr 20), during the DSS-55 support for Ahead, turbo decoder lock was lost intermittently beginning at 0817z through 1441z due to rain at the Madrid complex. This anomaly resulted in the loss of 3505 frames of real-time telemetry and SSR data, which corresponds to a loss of several minutes over a 1-2 hour period. See DR# M109313 for more information. * On day 112 (Apr 21), during the DSS-26 support for Ahead, turbo decoder lock was lost briefly at 113-0145z. This anomaly resulted in the loss of 7 frames of SSR data. * On day 113 (Apr 22), during the DSS-63 support for Ahead, turbo decoder lock was lost briefly at 1401z. This anomaly resulted in the loss of 4 frames of real-time and SSR data. * On day 114 (Apr 23), during the DSS-25 support for Ahead, turbo decoder lock was lost intermittently beginning at 1641z through 1913z. This anomaly resulted in the loss of 4 frames of real-time and SSR data. * On day 115 (Apr 24), during the DSS-25 support for Ahead, turbo decoder lock was lost briefly at 2102z. 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 105 degrees C and decreasing with the HGA angle at 10.1 degrees and increasing, with respect to the spacecraft-Sun line. This temperature is somewhat warmer than predicted, but the temperature is definitely going down. * The average daily science data return for Ahead was 5.4 Gbits during this week. * There were no tracks for Behind during the week. * The next uplink array attempt for Behind will be May 13, 14. As time goes on, the ephemeris error increases, but the decreasing range is the dominant effect, so the signal strength will improve with time. 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 three 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 were underway at the time of the telecon, with battery recovery tracks yesterday and today (Apr 25-26), and carrier recovery tomorrow (Apr 27) listening with station 63. The battery recovery tracks are being 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. Station 14 has been unavailable since the end of January. * 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 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 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) * 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. Other * SECCHI requested another calibration roll be scheduled, since the sudden change in the COR1-A background on Apr 13 made the previous roll obsolete for that telescope. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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) ------------------------------------------------------------------------------- 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 ------------------------------------------------------------------------------- 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