STEREO Weekly Meeting Minutes for 2017-05-30 (Week 22) 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 21 (May 22-28) * On day 143 (May 23), during the DSS-14 support for Ahead, receipt of real-time telemetry and monitor data and commanding was 53 minutes late as a result of a power anomaly at the Goldstone complex that affected the JPL to MOC communications. The antenna was tracking nominally and all telemetry data was being recorded at the station. Once communications were restored, the MOC received telemetry at 1853z and all SSR data were recovered. This anomaly resulted in the loss of 53 minutes of real-time telemetry, commanding, and monitor data. See DR #N110599 for more information. * On day 145 (May 25), during the DSS-14 support for Ahead, the transmitter was declared red just before BOT (2300z). Maintenance was eventually able to resolve the issue, and the uplink established at 2313z. This anomaly resulted in the loss of 4.75 minutes of real-time data and 2.75 minutes of SSR data due to a late BOT (2304z), and an additional loss of 6338 frames of SSR data between 2304z and 2359z due to intermittent loss of turbo decoder lock. Note that currently there is a data gap for all instruments from 144-1853z through 2350z that is larger than it should be. The MOC is investigating. See DRs #G118164 and #G118165 for more information. * On day 148 (May 28), during the DSS-63 support for Ahead, turbo decoder lock was lost intermittently between 1641z and 1643z. This anomaly resulted in the loss of 1885 frames of SSR data. See DR #N110610 for more information. * On day 142 (May 22), the 99th momentum dump on Ahead was executed successfully at 1400z, which imparted an estimated delta V of 0.084 m/sec. This was the 18th momentum dump that did not use the IMU. After thruster operations completed, there was a 0.49 degree of roll angle error which was dampened out over the next 6.5 minutes. Fine pointing stabilized 2.8 minutes after completion of the momentum dump. * On day 143 (May 23), during the DSS-14 support for Ahead, the IMPACT team conducted real-time commanding to increase the Magnetometer instrument's high rate data return. * The average daily science data return for Ahead was 6.2 Gbits during this week. * The next recovery attempts for Behind are Jun 9-11. There will be a recovery planning meeting and telecon on Thursday, Jun 1, starting at 9:00 AM. Week 22 (May 29-Jun 4) * 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. * There will be an uplink rate test on Tuesday, Jun 6, during the station 63 support. This test in preparation for recoverying Behind, and will test intermediate rates between 7.8 bps and 125 bps. The results from the previous tests to recover Behind showed that there was some uplink margin which should allow rates faster than 7.8 bps. Time tagged commands will ensure that Ahead is back to the nominal rate at the end of the test. * 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 80-88% 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) * DSN stations will be down for several hours on Jun 26 for a "Follow the Sun" exercise. STEREO Ahead has tracks scheduled before and after this event, and will not be affected. * 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. Week 27 (Jul 3-9) * Tuesday, July 4, is Independence Day, which is a holiday at APL. * Ahead has 9 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, one at 240 kbps, and one at 160 kbps. * There are no tracks for Behind during the week. Week 28 (Jul 10-16) * Ahead has 11 tracks during the week, and overall coverage is nominal. There are eight tracks at 720 kbps, two at 240 kbps, and one at 160 kbps. * Recovery operations for Behind switch from a monthly to a weekly schedule. Three 4 hour tracks per week are scheduled, spaced so that if any commands do reach the spacecraft, the command loss timer won't have a chance to fire before the next track. Behind recovery tracks are scheduled for Tuesday, Thursday, and Saturday, Jul 11, 13, and 15. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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) Ahead: Uplink rate test with station 63 W Jun 07 (158) T Jun 08 (159) F Jun 09 (160) Behind: Battery recovery track with station 26 S Jun 10 (161) Behind: Battery recovery track with station 26 S Jun 11 (162) Behind: Carrier recovery track with station 43 ------------------------------------------------------------------------------- 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) DSN stations down for "Follow the Sun" exercise 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) ------------------------------------------------------------------------------- Scheduled activities for Week 27: M Jul 03 (184) T Jul 04 (185) Independence Day W Jul 05 (186) T Jul 06 (187) F Jul 07 (188) S Jul 08 (189) S Jul 09 (190) ------------------------------------------------------------------------------- Scheduled activities for Week 28: M Jul 10 (191) T Jul 11 (192) Behind: Recovery track W Jul 12 (193) T Jul 13 (194) Behind: Recovery track F Jul 14 (195) S Jul 15 (196) Behind: Recovery track S Jul 16 (197) Notes: * Start of weekly recovery attempts to recovery Behind spacecraft. ------------------------------------------------------------------------------- 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