STEREO Weekly Meeting Minutes for 2017-06-13 (Week 24) 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 23 (Jun 5-11) * On day 161 (Jun 10), during the DSS-63 support for Ahead, turbo decoder lock was lost briefly at 1909z. This anomaly resulted in the loss of 11 frames of SSR data. * On day 157 (Jun 6), uplink rates of 15, 31, 62, and 250 bps were tested successfully on the Ahead observatory in preparation for use during Behind recovery. These uplink rates were never tested prelaunch with the DSN as the mission had no need for them. During the attempt to recover Behind last year, it was realized that there was sufficient margin to increase the rate, but to the next available rate at the time of 125 bps. * On day 159 (Jun 8), the SECCHI instrument on Ahead reset at 19:25:41z. The SECCHI team reconfigured the instrument to operational mode by 160-1700z. This was the 45th reset of SECCHI on the Ahead observatory. * The average daily science data return for Ahead was 5.4 Gbits during this week. * On day 160 (Jun 9), during a 4.1 hour support for Behind recovery with the 34m station DSS-26 using the 80 kW transmitter to minimize 70m contentions, the uplink and both receivers were not configured at BOT due to an issue building the link. This anomaly resulted in the loss of 0.67 hours of command capability. Also, the command uplink was incorrectly configured once the link was built. This anomaly resulted in one of the three sets of transmitter on commands not being radiated properly. A total of 432 commands were transmitted during the support. No carrier was detected by the DSN station after attempting to power on the TWTA for 20 minutes. Transitioned to battery recovery operations for the remainder of the support which consists of repeatedly sweeping a 4 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. See DR #G118201 for more information. * On day 161, during a 4.5 hour support for Behind recovery with the 34m station DSS-26 using the 80 kW transmitter to minimize 70m contentions, the command uplink was incorrectly configured for the first hour of the track. This anomaly resulted in the first 100 commands not being radiated properly, including the three sets of transmitter on commands. Only battery recovery commands were transmitted during the track. A total of 482 commands were transmitted during the support. No carrier was detected by the DSN station. * On day 162, during a 4.3 hour support for Behind recovery with DSS-43, 460 commands were transmitted during the support. No carrier was detected by either the DSN station or the radio science receiver team after attempting to power on the TWTA for 30 minutes. Transitioned to battery recovery operations for the remainder of the support which consists of repeatedly sweeping a 4 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. * The next recovery attempt for Behind will be on July 11, when the recovery schedule switches from monthly to weekly. A recovery pass will be schedule once every about 3 days, to stay within the hard command loss timer firing limit. This will average to about 3 passes per week, with the first week consisting of passes on July 11, 13, 15. On Aug 21, the schedule will switch to daily recovery attempts. * The MOC will schedule a readiness review for Behind recovery in the near future. * The most likely period for communicating with Behind is felt to be late September through October. The recovery attempt last year suggested that communication may have been possible a few weeks earlier than the first successful attempt, so the plan is to start early to not miss any available opportunity. Week 24 (Jun 12-18) * STEREO Ahead reached aphelion today (Jun 13). * The 39th SECCHI stepped calibration roll was carried out earlier this morning (Jun 13). * 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. The maintenance is backed up with time tagged commands and autonomy rules to return to normal operations. This maintenance is done annually. * 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 14 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. The Radio Science Receiver will be operating during all tracks. Week 29 (Jul 17-23) * Ahead has 11 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, two at 360 kbps, one at 240 kbps, and two at 160 kbps. * Recovery tracks for Behind are scheduled on Tuesday, Wednesday, and Saturday. The Radio Science Receiver will be operating during all tracks. Week 30 (Jul 24-30) * A 2.6 hour project interface test has been scheduled with Ahead using station 24 on Saturday, Jul 29. There will be no instrument commanding or SSR playback during this track. The downlink rate will be 160 kbps. * Ahead has 9 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, one at 360 kbps, and one at 240 kbps. * Recovery tracks for Behind are scheduled on Monday, Tuesday, Friday, and Saturday, July 24, 25, 28, 29. The Radio Science Receiver will be operating during all tracks. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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 with station 63 W Jul 12 (193) T Jul 13 (194) Behind: Recovery track with station 43 F Jul 14 (195) S Jul 15 (196) Behind: Recovery track with station 43 S Jul 16 (197) Notes: * Start of weekly recovery attempts to recovery Behind spacecraft. ------------------------------------------------------------------------------- Scheduled activities for Week 29: M Jul 17 (198) T Jul 18 (199) Behind: Recovery track with station 63 W Jul 19 (200) Behind: Recovery track with station 43 T Jul 20 (201) F Jul 21 (202) S Jul 22 (203) Behind: Recovery track with station 63 S Jul 23 (204) ------------------------------------------------------------------------------- Scheduled activities for Week 30: M Jul 24 (205) Behind: Recovery track with station 63 T Jul 25 (206) Behind: Recovery track with station 63 W Jul 26 (207) T Jul 27 (208) F Jul 28 (209) Behind: Recovery track with station 63 S Jul 29 (210) Ahead: Project interface test with station 24 Behind: Recovery track with station 63 S Jul 30 (211) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2017: * Aug 21 Behind: Switch to daily recovery attempts 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