STEREO Weekly Meeting Minutes for 2017-05-16 (Week 20) ANNOUNCEMENTS ------------- * None. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * Attempts to recover Behind have transitioned back to a monthly schedule. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 19 (May 8-14) * On day 130 (May 10), during the DSS-14 support for Ahead, turbo decoder lock was lost briefly at 2234z. This anomaly resulted in the loss of 457 frames of real-time telemetry and SSR data. See DR #N110585 for more information. * On day 132 (May 12), during the DSS-43 support for Ahead, turbo decoder lock was lost briefly at 0621z. This anomaly resulted in the loss of five frames of SSR data. * On day 133 (May 13), during the DSS-43 support for Ahead, turbo decoder lock was lost intermittently between 0525z and 0709z. This anomaly resulted in the loss of 52 frames of real-time telemetry and SSR data. * On day 134 (May 14), during the DSS-63 support for Ahead, turbo decoder lock was lost briefly at 0725z and again at 0756z. This anomaly resulted in the loss of 1194 frames of real-time telemetry and SSR data. See DR #N110586 for more information. * On day 133 (May 13), the Ahead observatory was used to phase calibrate the 12th uplink array, using DSS-24, 25, and 26 for 1.9 hours, to support the array use for STEREO Behind battery recovery. An approximate 12 dB gain in uplink AGC was observed in the spacecraft transponder data. No SSR playback was conducted as the phasing of the transmitters would have caused periodic dropped frames. * On day 134 (May 14), the Ahead observatory was used again to phase calibrate the 13th uplink array, using DSS-24, 25, and 26 for 1.9 hours, to support the array use for STEREO Behind transmitter carrier recovery. An approximate 12 dB gain in uplink AGC was observed in the spacecraft transponder data. No SSR playback was conducted as the phasing of the transmitters would have caused periodic dropped frames. * The average daily science data return for Ahead was 6.3 Gbits during this week. * On day 133 (May 13), the 12th uplink array for STEREO Behind recovery was conducted using DSS-24, 25, and 26 for a duration of 2.8 hours. The uplink array was phase calibrated to provide approximate 12 dB gain, as compared to a single 34m station, using the Ahead observatory first for 1.9 hours then the arrayed stations were switched to point to the Behind observatory. The configuration consisted of three 34m stations at the Goldstone complex using the 80 kW and two 20 kW transmitters repeating a 4 kHz frequency acquisition sequence with the MOC sending 20 critical commands after each sweep. 300 commands were sent for battery recovery. * On day 134 (May 14), the 13th uplink array for STEREO Behind recovery was conducted using DSS-24, 25, and 26 for a duration of 3.7 hours. The uplink array was phase calibrated to provide approximate 12 dB gain, as compared to a single 34m station, using the Ahead observatory first for 1.9 hours then the arrayed stations were switched to point to the Behind observatory. The configuration consisted of three 34m stations at the Goldstone complex using the 80 kW and two 20 kW transmitters repeating a 4 kHz frequency acquisition sequence with the MOC sending 20 critical commands after each sweep. 400 commands were sent for carrier recovery. The DSN 70m station DSS-14 monitored the downlink along with the radio science receiver team, however, no downlink signal was detected. Week 20 (May 15-21) * Command uplink was late yesterday (May 15), resulting in the loss of some data when the uplink frequency was reswept. * Turbo decoder lock was lost briefly duing the station 14 pass for Ahead at 02:48 UT this morning (May 16), resulting in the loss of 5 frames of data. * Ahead has 12 passes during the week, and overall coverage is nominal. There are eight passes at 720 kbps, one at 360 kbps, one at 240 kbps, and two at 160 kbps. * There are no passes for Behind during the week. Week 21 (May 22-28) * The 99th momentum dump on Ahead is scheduled for Monday, May 22, with ignition at 14:00 UT. This will be the 18th momentum dump without using the gyros. The dump is being scheduled a week or so early due to track coverage limitations. * Ahead has 8 passes during the week, and overall coverage is nominal. There are seven passes at 720 kbps, and one at 240 kbps. * There are no passes for Behind during the week. Week 22 (May 29-Jun 4) * Monday, May 29, is Memorial Day, which is a holiday at APL. * There will be an upgrade of the restricted IOnet on Thursday, June 1, between 11-19 UT. This will occur between tracks, and is expected to have no effect. * Ahead has 8 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, and one at 160 kbps. * There are no tracks for Behind during the week. Week 23 (Jun 5-11) * Monday, Jun 5, 14-20 UT, is a backup date for the IOnet upgrade scheduled for the previous Thursday. This will also be between tracks. * Ahead has 9 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, one at 240 kbps, and two at 160 kbps. * Recovery tracks for Behind are scheduled for Friday, Saturday, and Sunday, Jun 9-11. The first two tracks will use the 80 kW transmitter on station 26. The last track will use station 43, and will include the Radio Science Receiver. Week 24 (Jun 12-18) * STEREO Ahead reaches aphelion on Jun 13. * The 39th SECCHI stepped calibration roll is scheduled for Tuesday, Jun 13, starting at 09:15 UT. System momentum is expected to be 1 N-m-s. This will be the eighth calibration roll without gyros. * Battery discharge maintenance will be carried out on Ahead on Wednesday, Jun 14, for 2 hours starting at 15:00 UT during a track. The battery state of charge will be taken down to 86-88% for testing. This is not expected to affect science operations. * Ahead has 10 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, three at 240 kbps, and one at 160 kbps. * There are no tracks for Behind during the week. Week 25 (Jun 19-25) * Ahead has 10 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, and four at 240 kbps. * There are no tracks for Behind during the week. Week 26 (Jun 26-Jul 2) * The 100th momentum dump on Ahead is scheduled for Jun 29, starting at 17:30 UT. This will be the 19th dump without using the gyros. * Ahead has 13 tracks during the week, and overall coverage is nominal There are eight tracks at 720 kbps, three at 240 kbps, and two at 160 kbps. * There are no tracks for Behind during the week. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 20: M May 15 (135) T May 16 (136) W May 17 (137) T May 18 (138) F May 19 (139) S May 20 (140) S May 21 (141) ------------------------------------------------------------------------------- Scheduled activities for Week 21: M May 22 (142) Ahead: Momentum dump, 14:00 UT T May 23 (143) W May 24 (144) T May 25 (145) F May 26 (146) S May 27 (147) S May 28 (148) ------------------------------------------------------------------------------- Scheduled activities for Week 22: M May 29 (149) Memorial Day T May 30 (150) W May 31 (151) T Jun 01 (152) F Jun 02 (153) S Jun 03 (154) S Jun 04 (155) ------------------------------------------------------------------------------- Scheduled activities for Week 23: M Jun 05 (156) T Jun 06 (157) W Jun 07 (158) T Jun 08 (159) F Jun 09 (160) S Jun 10 (161) S Jun 11 (162) ------------------------------------------------------------------------------- Scheduled activities for Week 24: M Jun 12 (163) T Jun 13 (164) Ahead: Aphelion. SECCHI calibration roll, 09:15 UT W Jun 14 (165) Ahead: Battery discharge maintenance, 15:00 UT T Jun 15 (166) F Jun 16 (167) S Jun 17 (168) S Jun 18 (169) ------------------------------------------------------------------------------- Scheduled activities for Week 25: M Jun 19 (170) T Jun 20 (171) W Jun 21 (172) T Jun 22 (173) F Jun 23 (174) S Jun 24 (175) S Jun 25 (176) ------------------------------------------------------------------------------- Scheduled activities for Week 26: M Jun 26 (177) T Jun 27 (178) W Jun 28 (179) T Jun 29 (180) Ahead: Momentum dump, 17:30 UT F Jun 30 (181) S Jul 01 (182) S Jul 02 (183) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 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 2022: 2023: * May 5 Behind: Mercury transit * Jul 17 Behind: Closest approach to Earth * Aug 13 Ahead: Closest approach to Earth 2024: 2025: * Apr 7 Ahead: Mercury transit 2026: 2027: * Feb 1 Behind: Mercury transit 2028: 2029: * Jun 30 Ahead: Mercury transit